DS1874T+

19-4691; Rev 0; 6/09 SFP+ Controller with Digital LDD Interface The DS1874 controls and monitors all functions for SFF, SFP, and SFP+ modules including all SFF-8472 functionality. The combination of the DS1874 with the MAX3798/MAX3799 laser driver/limiting amplifier provides APC loop, modulation current control, and eye safety functionality. The DS1874 continuously monitors for high output current, high bias current, and low and high transmit power to ensure that laser shutdown for eye safety requirements are met without adding external components. Six ADC channels monitor VCC, temperature, and four external monitor inputs (MON1–MON4) that can be used to meet all monitoring requirements. MON3 is differential with support for common mode to VCC. Two digital-to-analog (DAC) outputs with temperature-indexed lookup tables (LUTs) are available for additional monitoring and control functionality. Applications SFF, SFP, and SFP+ Transceiver Modules DAC2 DAC1 REFIN GND MON2 VCC TOP VIEW GND Pin Configuration 21 20 19 18 17 16 15 N.C. 22 14 MON1 VCC 23 13 MON3N CSELOUT 24 12 MON3P 11 MON4 10 TXDOUT 9 RSEL 8 GND SCLOUT 25 DS1874 SDAOUT 26 LOSOUT 27 *EP + 1 2 3 4 5 6 7 RSELOUT SCL SDA TXF LOS IN1 TXD OUT1 28 THIN QFN (5mm × 5mm × 0.8mm) *EXPOSED PAD. Features ♦ Meets All SFF-8472 Control and Monitoring Requirements ♦ Laser Bias Controlled by APC Loop and Temperature LUT to Compensate for Tracking Error ♦ Laser Modulation Controlled by Temperature LUT ♦ Six Analog Monitor Channels: Temperature, VCC, MON1–MON4 MON1–MON4 Support Internal and External Calibration Scalable Dynamic Range Internal Direct-to-Digital Temperature Sensor Alarm and Warning Flags for All Monitored Channels ♦ Two 9-Bit Delta-Sigma Outputs with 36 Entry Temperature LUTs ♦ Digital I/O Pins: Five Inputs, Five Outputs ♦ Comprehensive Fault-Measurement System with Maskable Laser Shutdown Capability ♦ Flexible, Two-Level Password Scheme Provides Three Levels of Security ♦ 256 Additional Bytes Located at A0h Slave Address ♦ I2C-Compatible Interface ♦ 3-Wire Master to Communicate with the MAX3798/ MAX3799 Laser Driver/Limiting Amplifier ♦ +2.85V to +3.9V Operating Voltage Range ♦ -40°C to +95°C Operating Temperature Range ♦ 28-Pin TQFN (5mm x 5mm) Package Ordering Information PART TEMP RANGE PIN-PACKAGE DS1874T+ -40°C to +95°C 28 TQFN-EP* DS1874T+T&R -40°C to +95°C 28 TQFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. T&R = Tape and reel. *EP = Exposed pad. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 DS1874 General Description DS1874 SFP+ Controller with Digital LDD Interface TABLE OF CONTENTS Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 DAC1, DAC2 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Analog Quick-Trip Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Analog Voltage Monitoring Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Digital Thermometer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 AC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Timing Characteristics (Control Loop and Quick Trip) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 3-Wire Digital Interface Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 I2C AC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Nonvolatile Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Typical Operating Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 MAX3798/MAX3799 DAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 BIAS Register/APC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 MODULATION Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 BIAS and MODULATION Control During Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 BIAS and MODULATION Registers as a Function of Transmit Disable (TXD) . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 APC and Quick-Trip Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Monitors and Fault Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Five Quick-Trip Monitors and Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Six ADC Monitors and Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 ADC Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Right-Shifting ADC Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Enhanced RSSI Monitoring (Dual-Range Functionality) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 Low-Voltage Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Power-On Analog (POA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Delta-Sigma Outputs (DAC1 and DAC2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Digital I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 LOS, LOSOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 IN1, RSEL, OUT1, RSELOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 TXF, TXD, TXDOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 2 _______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Transmit Fault (TXF) Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Die Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 3-Wire Master for Controlling the MAX3798/MAX3799 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 3-Wire Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 DS1874 and MAX3798/MAX3799 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 MAX3798/MAX3799 Register Map and DS1874 Corresponding Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 I2C Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 I2C Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 I2C Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 Shadowed EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Lower Memory Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Table 01h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Table 02h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Table 04h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Table 05h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Table 06h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Table 07h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Table 08h Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Auxiliary A0h Memory Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Lower Memory Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 Table 01h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48 Table 02h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55 Table 04h Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84 Table 06h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85 Table 07h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86 Table 08h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Auxiliary Memory A0h Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 Power-Supply Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 SDA and SCL Pullup Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 _______________________________________________________________________________________ 3 DS1874 TABLE OF CONTENTS (continued) DS1874 SFP+ Controller with Digital LDD Interface LIST OF FIGURES Figure 1. Modulation LUT Loading to MAX3798/MAX3799 MOD DAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Figure 2. Power-Up Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Figure 3. TXD Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Figure 4. APC Loop and Quick-Trip Sample Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Figure 5. ADC Round-Robin Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 Figure 6. MON3 Differential Input for High-Side RSSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 Figure 7. RSSI Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Figure 8. Low-Voltage Hysteresis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Figure 9. Recommended RC Filter for DAC1/DAC2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 Figure 10. Delta-Sigma Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 Figure 11. DAC1/DAC2 LUT Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 Figure 12. Logic Diagram 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 Figure 13. Logic Diagram 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Figure 14a. TXF Nonlatched Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Figure 14b. TXF Latched Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Figure 15. 3-Wire Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Figure 16. 3-Wire State Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 Figure 17. I2C Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 Figure 18. Example I2C Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 Figure 19. Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 LIST OF TABLES Table 1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Table 2. Update Rate Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Table 3. ADC Default Monitor Full-Scale Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Table 4. MON3 Hysteresis Threshold Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Table 5. MON3 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 4 _______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Operating Temperature Range ...........................-40°C to +95°C Programming Temperature Range .........................0°C to +95°C Storage Temperature Range .............................-55°C to +125°C Soldering Temperature...........................Refer to the IPC/JEDEC J-STD-020 Specification. *Subject to not exceeding +6V. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS (TA = -40°C to +95°C, unless otherwise noted.) PARAMETER SYMBOL MAX UNITS +2.85 +3.9 V VIH:1 0.7 x VCC VCC + 0.3 V Low-Level Input Voltage (SDA, SCL, SDAOUT) VIL:1 -0.3 0.3 x VCC V High-Level Input Voltage (TXD, TXF, RSEL, IN1, LOS) VIH:2 2.0 VCC + 0.3 V Low-Level Input Voltage (TXD, TXF, RSEL, IN1, LOS) VIL:2 -0.3 +0.8 V TYP MAX UNITS 2.5 10 mA 1 μA Main Supply Voltage VCC High-Level Input Voltage (SDA, SCL, SDAOUT) CONDITIONS (Note 1) MIN TYP DC ELECTRICAL CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER SYMBOL Supply Current ICC Output Leakage (SDA, SDAOUT, OUT1, RSELOUT, LOSOUT, TXF) ILO Low-Level Output Voltage (SDA, SDAOUT, SCLOUT, CSELOUT, OUT1, RSELOUT, LOSOUT, TXDOUT, DAC1, DAC2, TXF) VOL High-Level Output Voltage (DAC1, DAC2, SCLOUT, SDAOUT, CSELOUT, TXDOUT) VOH CONDITIONS MIN (Notes 1, 2) I OL = 4mA 0.4 I OL = 6mA 0.6 V I OH = 4mA VCC 0.4 TXDOUT Before EEPROM Recall DAC1 and DAC2 Before LUT Recall Input Leakage Current (SCL, TXD, LOS, RSEL, IN1) Figure 11 ILI V 10 100 nA 10 100 nA 1 μA Digital Power-On Reset POD 1.0 2.2 V Analog Power-On Reset POA 2.0 2.75 V _______________________________________________________________________________________ 5 DS1874 ABSOLUTE MAXIMUM RATINGS Voltage Range on MON1–MON4, RSEL, IN1, LOS, TXF, and TXD Pins Relative to Ground .................................-0.5V to (VCC + 0.5V)* Voltage Range on VCC, SDA, SCL, OUT1, RSELOUT, and LOSOUT Pins Relative to Ground.................................................-0.5V to +6V DS1874 SFP+ Controller with Digital LDD Interface DAC1, DAC2 ELECTRICAL CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER Main Oscillator Frequency Delta-Sigma Input-Clock Frequency Reference Voltage Input (REFIN) SYMBOL CONDITIONS TYP MAX UNITS f OSC 5 MHz fDS f OSC/2 MHz VREFIN Minimum 0.1μF to GND Output Range 2 VCC V 0 VREFIN V 9 Bits 35 100
TYP MAX UNITS See the Delta-Sigma Outputs (DAC1 and DAC2) section for details. Output Resolution Output Impedance MIN RDS ANALOG QUICK-TRIP CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER MON2, TXP HI, TXP LO FullScale Voltage SYMBOL CONDITIONS MIN VAPC HBIAS, LOS Full-Scale Voltage MON2 Input Resistance 35 Resolution Error TA = +25°C 2.5 V 1.25 V 50 65 k
8 Bits ±2 %FS Integral Nonlinearity -1 +1 LSB Differential Nonlinearity -1 +1 LSB +2.5 %FS Temperature Drift -2.5 LOS Offset -5 mV ANALOG VOLTAGE MONITORING CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS ADC Resolution ACC Update Rate for Temperature, MON1–MON4, and VCC tRR Input/Supply Offset (MON1–MON4, VCC) VOS At factory setting MAX VCC MON3 Fine UNITS Bits 0.25 0.50 %FS 64 75 ms (Note 3) 0 5 LSB (Note 4) 6.5536 MON1–MON4 6 TYP 13 Input/Supply Accuracy (MON1–MON4, VCC) Factory Setting MIN 2.5 312.5 _______________________________________________________________________________________ V μV SFP+ Controller with Digital LDD Interface DS1874 DIGITAL THERMOMETER CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER Thermometer Error SYMBOL T ERR CONDITIONS -40°C to +95°C MIN TYP -3 MAX UNITS +3 °C MAX UNITS AC ELECTRICAL CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP TXD Enable t OFF From
TXD (Notes 5, 6) 5 μs Recovery from TXD Disable (Figure 14) t ON From  TXD (Notes 5, 7) 1 ms Recovery After Power-Up Fault Reset Time (to TXF = 0) Fault Assert Time (to TXF = 1) From
VCC > VCC LO alarm (Notes 5, 8) 20 t INITR1 From  TXD 131 t INITR2 From
VCC > VCC LO alarm (Note 8) 161 tFAULT After HTXP, LTXP, HBATH, IBIASMAX (Note 9) 6.4 55 μs tINIT_DAC ms ms LOSOUT Assert Time tLOSS_ON LLOS (Notes 9, 10) 6.4 55 μs LOSOUT Deassert Time tLOSS_OFF HLOS (Notes 9, 11) 6.4 55 μs MAX UNITS TIMING CHARACTERISTICS (CONTROL LOOP AND QUICK TRIP) (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, unless otherwise noted.) PARAMETER SYMBOL Output-Enable Time Following POA tINIT (Note 8) tSEARCH (Note 12) Binary Search Time CONDITIONS MIN TYP 20 8 ms 10 BIAS Samples 3-WIRE DIGITAL INTERFACE SPECIFICATION (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, timing referenced to VIL(MAX) and VIH(MIN), unless otherwise noted. See Figure 15.) PARAMETER SCLOUT Clock Frequency SCLOUT Duty Cycle SYMBOL fSCLOUT CONDITIONS MIN (Note 13) t3WDC TYP MAX UNITS 833 kHz 50 % SDAOUT Setup Time tDS 100 ns SDAOUT Hold Time tDH 100 ns tCSW 500 ns CSELOUT Leading Time Before the First SCLOUT Edge tL 500 ns CSELOUT Trailing Time After the Last SCLOUT Edge tT 500 ns CSELOUT Pulse-Width Low SDAOUT, SCLOUT Load CB3W (Note 14) Total bus capacitance on one line (Note 14) 10 pF _______________________________________________________________________________________ 7 DS1874 SFP+ Controller with Digital LDD Interface I2C AC ELECTRICAL CHARACTERISTICS (VCC = +2.85V to +3.9V, TA = -40°C to +95°C, timing referenced to VIL(MAX) and VIH(MIN), unless otherwise noted. See Figure 17.) PARAMETER SYMBOL SCL Clock Frequency Clock Pulse-Width Low Clock Pulse-Width High Bus-Free Time Between STOP and START Condition START Hold Time START Setup Time Data Out Hold Time Data In Setup Time Rise Time of Both SDA and SCL Signals Fall Time of Both SDA and SCL Signals STOP Setup Time EEPROM Write Time Capacitive Load for Each Bus Line f SCL tLOW tHIGH CONDITIONS (Note 13) tBUF tHD:STA t SU:STA tHD:DAT t SU:DAT tR tF t SU:STO tW CB MIN TYP 0 1.3 0.6 MAX UNITS 400 kHz μs μs 1.3 (Note 14) (Note 14) μs 0.6 0.6 0 100 20 + 0.1CB 20 + 0.1CB 0.6 20 400 μs μs μs ns ns ns μs ms pF MAX UNITS 0.9 300 300 (Note 15) NONVOLATILE MEMORY CHARACTERISTICS (VCC = +2.85V to +3.9V, unless otherwise noted.) PARAMETER EEPROM Write Cycles Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: Note 14: Note 15: 8 SYMBOL CONDITIONS MIN At +25°C 200,000 At +85°C 50,000 TYP All voltages are referenced to ground. Current into the IC is positive, and current out of the IC is negative. Inputs are at supply rail. Outputs are not loaded. This parameter is guaranteed by design. Full-scale is user programmable. The DACs are the bias and modulation DACs found in the MAX3798/MAX3799 that are controlled by the DS1874. The DS1874 is configured with TXDOUT connected to the MAX3798/MAX3799 DISABLE input. This includes writing to the modulation DAC and the initial step written to the bias DAC. A temperature conversion is completed and the modulation register value is recalled from the LUT and VCC has been measured to be above VCC LO alarm. The timing is determined by the choice of the update rate setting (see Table 02h, Register 88h). This specification is the time it takes from MON3 voltage falling below the LLOS trip threshold to LOSOUT asserted high. This specification is the time it takes from MON3 voltage rising above the HLOS trip threshold to LOSOUT asserted low. Assuming an appropriate initial step is programmed that would cause the power to exceed the APC set point within four steps, the bias current will be within 3% within the time specified by the binary search time. See the BIAS and MODULATION Control During Power-Up section. I2C interface timing shown is for fast mode (400kHz). This device is also backward compatible with I2C standard mode timing. CB—the total capacitance of one bus line in pF. EEPROM write begins after a STOP condition occurs. _______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface SDA = SCL = VCC 2.6 +95°C 2.5 2.3 -40°C 2.1 +25°C 1.9 VCC = 3.9V 2.5 2.4 2.3 VCC = 2.85V VCC = 3.3V 2.2 USING FACTORY-PROGRAMMED FULL-SCALE VALUE OF 2.5V 0.8 0.6 MON1–MON4 INL (LSB) SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 2.7 1.0 DS1874 toc02 DS1874 toc01 SDA = SCL = VCC 2.9 MON1–MON4 INL SUPPLY CURRENT vs. TEMPERATURE 2.7 DS1874 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE 0.4 0.2 0 -0.2 -0.4 -0.6 1.7 2.1 1.5 2.0 3.10 3.35 3.60 3.85 -40 -20 0 VCC (V) MON1–MON4 DNL 60 80 0 0 -0.2 -0.4 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 0.5 1.0 1.5 2.0 MON1–MON4 INPUT VOLTAGE (V) 2.5 2.0 2.5 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -1.0 -1.0 1.5 DAC1 AND DAC2 INL DAC1 AND DAC2 INL (LSB) 0.2 1.0 2.0 DS1874 toc05 0.8 DAC1 AND DAC2 DNL (LSB) 0.4 0 0.5 MON1–MON4 INPUT VOLTAGE (V) 1.0 DS1874 toc04 USING FACTORY-PROGRAMMED FULL-SCALE VALUE OF 2.5V 0.6 MON1–MON4 DNL (LSB) 40 DAC1 AND DAC2 DNL 1.0 0.8 20 TEMPERATURE (°C) DS1874 toc06 2.85 -0.8 -1.0 0 100 200 300 400 DAC1 AND DAC2 POSITION (DEC) 500 0 100 200 300 400 500 DAC1 AND DAC2 POSITION (DEC) _______________________________________________________________________________________ 9 DS1874 Typical Operating Characteristics (VCC = +2.85V to +3.9V, TA = +25°C, unless otherwise noted.) SFP+ Controller with Digital LDD Interface DS1874 Pin Description 10 PIN NAME 1 RSELOUT FUNCTION 2 SCL I2C Serial-Clock Input 3 SDA I2C Serial-Data Input/Output Rate-Select Output 4 TXF Transmit-Fault Input and Output. The output is open drain. 5 LOS Loss-of-Signal Input 6 IN1 Digital Input. General-purpose input with AS1 in SFF-8079 or RS1 in SFF-8431. 7 TXD Transmit-Disable Input 8, 17, 21 GND Ground Connection 9 RSEL 10 TXDOUT Transmit-Disable Output 11 MON4 External Monitor Input 4 12, 13 MON3P, MON3N 14 MON1 15, 23 VCC 16 MON2 Rate-Select Input Differential External Monitor Input 3 and LOS Quick Trip External Monitor Input 1 and HBATH Quick Trip Power-Supply Input External Monitor Input 2. Feedback voltage for APC loop and HTXP/LTXP quick trip. 18 REFIN 19, 20 DAC1, DAC2 Reference Input for DAC1 and DAC2 22 N.C. 24 CSELOUT Chip-Select Output. Part of the 3-wire interface to the MAX3798/MAX3799 laser driver/limiting amplifier. 25 SCLOUT Serial-Clock Output. Part of the 3-wire interface to the MAX3798/MAX3799 laser driver/limiting amplifier. 26 SDAOUT Serial-Data Input/Output. Part of the 3-wire interface to the MAX3798/MAX3799 laser driver/limiting amplifier. 27 LOSOUT Open-Drain Receive Loss-of-Signal Output 28 OUT1 — EP Delta-Sigma Output 1/2 No Connection Digital Output. General-purpose output with AS1 output in SFF-8079 or RS1 output in SFF-8431. Exposed Pad ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface REFIN VCC MAIN MEMORY EEPROM/SRAM VCC SDA SCL I2C INTERFACE ADC CONFIGURATION/RESULTS, SYSTEM STATUS/CONTROL BITS, ALARMS/WARNINGS, LOOKUP TABLES, USER MEMORY 9-BIT DELTA-SIGMA DAC1 9-BIT DELTA-SIGMA DAC2 EEPROM 256 BYTES AT A0h SDAOUT VCC 3-WIRE INTERFACE 13-BIT ADC MON1 MON3P MON3N CSELOUT APC INTEGRATOR ANALOG MUX MON2 SCLOUT 8-BIT QTs MON4 TEMPERATURE SENSOR TXF POWER-ON ANALOG INTERRUPT VCC SEE FIGURE 12 TXD TXDOUT RSELOUT RSEL OUT1 IN1 SEE FIGURE 13 LOSOUT LOS DS1874 GND ______________________________________________________________________________________ 11 DS1874 Block Diagram SFP+ Controller with Digital LDD Interface DS1874 Typical Operating Circuit +3.3V 100Ω PIN-ROSA MAX3798/MAX3799 LA LOS 3W MODE DAC RSEL FAULT DISABLE BIAS DAC VCSEL-TOSA LDD BMON 3W DS1874 EEPROM MON1 MON2 TXF TXD TXDOUT QUICK TRIP I2C SDA SCL TX_FAULT TX_DISABLE MODE_DEF2 (SDA) MODE_DEF1 (SCL) ADC MON3 RBD RMON Detailed Description The DS1874 integrates the control and monitoring functionality required to implement a VCSEL-based SFP or SFP+ system using Maxim’s MAX3798/MAX3799 combined limiting amplifier and laser driver. Key components of the DS1874 are shown in the Block Diagram and described in subsequent sections. MAX3798/MAX3799 DAC Control The DS1874 controls two 9-bit DACs inside the MAX3798/MAX3799. One DAC is used for laser bias 12 LOS RSEL RSELOUT LOS LOSOUT RATE SELECT LOS control while the other is used for laser modulation control. The DS1874 communicates with the MAX3798/ MAX3799 over a 3-wire digital interface (see the 3-Wire Master for Controlling the MAX3798/MAX3799 section). The communication between the DS1874 and MAX3798/MAX3799 is transparent to the end user. BIAS Register/APC Control The MAX3798/MAX3799 control their laser bias current DAC using the APC loop within the DS1874. The APC loop’s feedback to the DS1874 is the monitor diode (MON2) current, which is converted to a voltage using ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface ACRONYM DEFINITION ADC Analog-to-Digital Converter AGC Automatic Gain Control APC Automatic Power Control APD Avalanche Photodiode ATB Alarm Trap Bytes BM Burst Mode DAC Digital-to-Analog Converter LOS Loss of Signal LUT Lookup Table NV Nonvolatile QT Quick Trip TE Tracking Error TIA MODULATION Control Transimpedance Amplifier ROSA Receiver Optical Subassembly SEE Shadowed EEPROM SFF Small Form Factor Document Defining Register Map of SFPs and SFFs SFF-8472 SFP Figure 1 demonstrates how the 8-bit LUT controls the 9-bit DAC with the use of a temperature control bit (MODTC, Table 02h, Register C6h) and a temperature index register (MODTI, Table 02h, Register C2h). Small Form Factor Pluggable SFP+ Enhanced SFP TOSA Transmit Optical Subassembly TXP The MAX3798/MAX3799 control the laser modulation using the internal temperature-indexed LUT within the DS1874. The modulation LUT is programmed in 2°C increments over the -40°C to +102°C range to provide temperature compensation for the laser’s modulation. The modulation is updated after each temperature conversion using the 3-wire interface that connects to the MAX3798/MAX3799. The MAX3798/MAX3799 include a 9-bit DAC. The modulation LUT is 8 bits. Transmit Power MODTI MODTI 8 8 MODTC = 1 7 MAX3798/MAX3799 DAC BIT MAX3798/MAX3799 DAC BIT MODTC = 0 6 5 4 MOD LUT LOADED TO [7:0] 3 MOD LUT LOADED TO [8:1] (DAC BIT 0 = 0) 2 1 7 6 MOD LUT LOADED TO [8:1] (DAC BIT 0 = 0) 5 4 3 MOD LUT LOADED TO [7:0] 2 1 0 0 -40 +102 TEMPERATURE (°C) -40 +102 TEMPERATURE (°C) Figure 1. Modulation LUT Loading to MAX3798/MAX3799 MOD DAC ______________________________________________________________________________________ 13 DS1874 an external resistor. The feedback is sampled by a comparator and compared to a digital set-point value. The output of the comparator has three states: up, down, or no-operation. The no-operation state prevents the output from excessive toggling once steady state is reached. As long as the comparator output is in either the up or down states, the bias is adjusted by writing increment and decrement values to the MAX3798/MAX3799 through the BIASINC register (3-wire address 13h). The DS1874 has an LUT to allow the APC set point to change as a function of temperature to compensate for tracking error (TE). The TE LUT has 36 entries that determine the APC setting in 4°C windows between -40°C to +100°C. Table 1. Acronyms DS1874 SFP+ Controller with Digital LDD Interface BIAS and MODULATION Control During Power-Up However, the BIAS MAX alarm is monitored during this time to prevent the BIAS register from exceeding IBIASMAX. During the bias current initialization, the BIAS register is not allowed to exceed IBIASMAX. If this occurs during the ISTEP sequence, then the binary search routine is enabled. If IBIASMAX is exceeded during the binary search, the next smaller step is activated. ISTEP or binary increments that would cause the BIAS register to exceed IBIASMAX are not taken. Masking the alarms until the completion of the binary search prevents false positive alarms during startup. ISTEP is programmed by the customer using Table 02h, Register BBh. During the first steps, the MAX3798/ MAX3799’s bias DAC is directly written using SET_IBIAS (3-wire address 09h). ISTEP should be programmed to the maximum safe increase that is allowable during startup. If this value is programmed too low, the DS1874 still operates, but it could take significantly longer for the algorithm to converge and hence to control the average power. If a fault is detected, and TXD is toggled to reenable the outputs, the DS1874 powers up following a similar sequence to an initial power-up. The only difference is that the DS1874 already has determined the present temperature, so the tINIT time is not required for the DS1874 to recall the APC and MOD set points from EEPROM. The DS1874 has two internal registers, MODULATION and BIAS, that represent the values written to the MAX3798/MAX3799’s modulation DAC and bias DAC through the 3-wire interface. On power-up, the DS1874 sets the MODULATION and BIAS registers to 0. When VCC is above POA, the DS1874 initializes the MAX3798/ MAX3799. After a temperature conversion is completed and if the VCC LO alarm is enabled, an additional VCC conversion above the customer-defined VCC LO alarm level is required before the MAX3798/MAX3799 MODULATION register is updated with the value determined by the temperature conversion and the modulation LUT. When the MODULATION register is set, the BIAS register is set to a value equal to ISTEP (see Figure 2). The startup algorithm checks if this bias current causes a feedback voltage above the APC set point, and if not, it continues increasing the BIAS register by ISTEP until the APC set point is exceeded. When the APC set point is exceeded, the device begins a binary search to quickly reach the bias current corresponding to the proper power level. After the binary search is completed, the APC integrator is enabled and single LSB steps are used to tightly control the average power. The TXP HI, TXP LO, HBAL, and BIAS MAX QT alarms are masked until the binary search is completed. VCC VPOA tINIT MODULATION REGISTER tSEARCH 4x ISTEP APC INTEGRATOR ON 3x ISTEP BIAS REGISTER BINARY SEARCH 2x ISTEP ISTEP BIAS SAMPLE 1 2 3 4 5 6 7 8 9 10 11 Figure 2. Power-Up Timing 14 ______________________________________________________________________________________ 12 13 SFP+ Controller with Digital LDD Interface If TXD is asserted (logic 1) during normal operation, the outputs are disabled within tOFF. When TXD is deasserted (logic 0), the DS1874 sets the MODULATION register with the value associated with the present temperature, and initializes the BIAS register using the same search algorithm as done at startup. When asserted, soft TXD (TXDC) (Lower Memory, Register 6Eh) would allow a software control identical to the TXD pin (see Figure 3). APC and Quick-Trip Timing As shown in Figure 4, the DS1874’s input comparator is shared between the APC control loop and the quicktrip alarms (TXP HI, TXP LO, LOS, and BIAS HI). The comparator polls the alarms in a multiplexed sequence. Five of every eight comparator readings are used for APC loop bias-current control. The other three updates are used to check the HTXP/LTXP (monitor diode voltage), the HBATH (MON1), and LOS (MON3) signals against the internal APC, BIAS, and MON3 reference, respectively. If the last APC comparison was higher than the APC set point, it makes an HTXP comparison, and if it is lower, it makes an LTXP comparison. Depending on the results of the comparison, the corresponding alarms and warnings (TXP HI, TXP LO) are asserted or deasserted. a wide variety of external filtering options and time delays resulting from writing values to the MAX3798/ MAX3799’s bias DAC. The UPDATE RATE register (Table 02h, Register 88h) determines the sampling time. Samples occur at a regular interval, tREP. Table 2 shows the sample rate options available. Any quick-trip alarm that is detected by default remains active until a subsequent comparator sample shows the condition no longer exists. A second bias current monitor (BIAS MAX) compares the MAX3798/MAX3799’s BIAS DAC’s code to a digital value stored in the IBIASMAX register. This comparison is made at every bias current update to ensure that a high-bias current is quickly detected. An APC sample that requires an update of the BIAS register causes subsequent APC samples to be Table 2. Update Rate Timing APC_SR[2:0] The DS1874 has a programmable comparator sample time based on an internally generated clock to facilitate SAMPLE PERIOD (tREP) (ns) 000b 800 001b 1200 010b 1600 011b 2000 100b 2800 101b 3200 110b 4400 111b 6400 TXD BIAS REGISTER tOFF tON MODULATION REGISTER tOFF tON Figure 3. TXD Timing APC QUICK-TRIP SAMPLE TIMES HBIAS SAMPLE APC SAMPLE APC SAMPLE APC SAMPLE APC SAMPLE APC SAMPLE HTXP/LTXP SAMPLE LOS SAMPLE HBIAS SAMPLE APC SAMPLE tREP Figure 4. APC Loop and Quick-Trip Sample Timing ______________________________________________________________________________________ 15 DS1874 BIAS and MODULATION Registers as a Function of Transmit Disable (TXD) DS1874 SFP+ Controller with Digital LDD Interface ignored until the end of the 3-wire communication that updates the MAX3798/MAX3799’s BIAS DAC, plus an additional 16 sample periods (tREP). Monitors and Fault Detection Monitors Monitoring functions on the DS1874 include five quick-trip comparators and six ADC channels. This monitoring combined with the alarm enables (Table 01h/05h) determines when/if the DS1874 turns off the MAX3798/ MAX3799 DACs and triggers the TXF and TXDOUT outputs. All the monitoring levels and interrupt masks are user programmable. Five Quick-Trip Monitors and Alarms Five quick-trip monitors are provided to detect potential laser safety issues and LOS status. These monitor the following: 1) High Bias Current (HBATH) 2) Low Transmit Power (LTXP) robin with a single ADC (see the ADC Timing section). The five voltage channels have a customer-programmable full-scale range and all channels have a customerprogrammable offset value that is factory programmed to default value (see Table 3). Additionally, MON1–MON4 can right-shift results by up to 7 bits before the results are compared to alarm thresholds or read over the I2C bus. This allows customers with specified ADC ranges to calibrate the ADC full scale to a factor of 1/2n of their specified range to measure small signals. The DS1874 can then right-shift the results by n bits to maintain the bit weight of their specification (see the Right-Shifting ADC Result and Enhanced RSSI Monitoring (Dual-Range Functionality) sections). Table 3. ADC Default Monitor Full-Scale Ranges SIGNAL +FS SIGNAL +FS hex -FS SIGNAL -FS hex 3) High Transmit Power (HTXP) 4) Max Output Current (IBIASMAX) Temperature (°C) 127.996 7FFF -128 8000 VCC (V) 6.5528 FFF8 0 0000 5) Loss-of-Signal (LOS LO) The high-transmit and low-transmit power quick-trip registers (HTXP and LTXP) set the thresholds used to compare against the MON2 voltage to determine if the transmit power is within specification. The HBATH quick trip compares the MON1 input (generally from the MAX3798/MAX3799 bias monitor output) against its threshold setting to determine if the present bias current is above specification. The BIAS MAX quick trip determines if the BIAS register is above specification. The BIAS register is not allowed to exceed the value set in the IBIASMAX register. When the DS1874 detects that the bias is at the limit it sets the BIAS MAX status bit and holds the BIAS register setting at the IBIASMAX level. The bias and power quick trips are routed to the TXF through interrupt masks to allow combinations of these alarms to be used to trigger these outputs. The user can program up to eight different temperatureindexed threshold levels for MON1 (Table 02h, Registers D0h–D7h). The LOS LO quick trip compares the MON3 input against its threshold setting to determine if the present received power is below the specification. The LOS LO quick trip can be used to set the LOSOUT pin. These alarms can be latched using Table 02h, Register 8Ah. MON1–MON4 (V) 2.4997 FFF8 0 0000 Six ADC Monitors and Alarms The ADC monitors six channels that measure temperature (internal temp sensor), VCC, and MON1–MON4 using an analog multiplexer to measure them round 16 The ADC results (after right-shifting, if used) are compared to the alarm and warning thresholds after each conversion, and the corresponding alarms are set, which can be used to trigger the TXF output. These ADC thresholds are user programmable, as are the masking registers that can be used to prevent the alarms from triggering the TXF output. ADC Timing There are six analog channels that are digitized in a round-robin fashion in the order shown in Figure 5. The total time required to convert all six channels is tRR (see the Analog Voltage Monitoring Characteristics for details). Right-Shifting ADC Result If the weighting of the ADC digital reading must conform to a predetermined full-scale (PFS) value defined by a standard’s specification (e.g., SFF-8472), then right-shifting can be used to adjust the PFS analog measurement range while maintaining the weighting of the ADC results. The DS1874’s range is wide enough to cover all requirements; when the maximum input value is ≤ 1/2 of the FS value, right-shifting can be used to obtain greater accuracy. For instance, the maximum voltage might be 1/8 the specified PFS value, so only 1/8 the converter’s range is effective over this range. An alternative is to calibrate the ADC’s full-scale range to 1/8 the readable PFS value and use a right-shift value of 3. With this implementation, the resolution of ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface DS1874 ONE ROUND-ROBIN ADC CYCLE TEMP VCC MON1 MON2 MON3 MON4 TEMP tRR NOTE: IF THE VCC LO ALARM IS ENABLED AT POWER-UP, THE ADC ROUND-ROBIN TIMING CYCLES BETWEEN TEMPERATURE AND VCC ONLY UNTIL VCC IS ABOVE THE VCC ALARM LOW THRESHOLD. Figure 5. ADC Round-Robin Timing VCC MON3P DS1874 ADC 100Ω MON3N ROSA Figure 6. MON3 Differential Input for High-Side RSSI the measurement is increased by a factor of 8, and because the result is digitally divided by 8 by rightshifting, the bit weight of the measurement still meets the standard’s specification (i.e., SFF-8472). The right-shift operation on the ADC result is carried out based on the contents of right-shift control registers (Table 02h, Registers 8Eh–8Fh) in EEPROM. Four analog channels, MON1–MON4, each have 3 bits allocated to set the number of right-shifts. Up to seven right-shift operations are allowed and are executed as a part of every conversion before the results are compared to the high-alarm and low-alarm levels, or loaded into their corresponding measurement registers (Lower Memory, Registers 64h–6Bh). This is true during the setup of internal calibration as well as during subsequent data conversions. Enhanced RSSI Monitoring (Dual-Range Functionality) The DS1874 offers a feature to improve the accuracy and range of MON3, which is most commonly used for monitoring RSSI. The accuracy of the RSSI measurements is increased at the small cost of reduced range (of input signal swing). The DS1874 eliminates this trade-off by offering “dual range” calibration on the MON3 channel (see Figure 6). This feature enables right-shifting (along with its gain and offset settings) when the input signal is below a set threshold (within the range that benefits using right-shifting) and then automatically disables right-shifting (recalling different gain and offset settings) when the input signal exceeds the threshold. Also, to prevent “chattering,” hysteresis prevents excessive switching between modes in addition to ensuring that continuity is maintained. Dual-range operation is enabled by default (factory programmed in EEPROM). However, it can easily be disabled through the RSSI_FC and RSSI_FF bits, which are described in the Register Descriptions section. When dual-range operation is disabled, MON3 operates identically to the other MON channels, although featuring a differential input. Dual-range functionality consists of two modes of operation: fine mode and coarse mode. Each mode is calibrated for a unique transfer function, hence the term, dual range. Table 5 highlights the registers related to MON3. Fine mode is equivalent to the other MON channels. Fine mode is calibrated using the gain, offset, and right-shifting registers at locations shown in Table 5 and is ideal for relatively small analog input voltages. Coarse mode is automatically switched to when the input exceeds a threshold (to be discussed in a subsequent paragraph). Coarse mode is calibrated using different gain and offset registers, but lacks right-shifting (since coarse mode is only used on large input signals). The gain and offset registers for coarse mode are also shown in Table 5. Additional information for each of the registers can be found in the Register Descriptions section. Dual-range operation is transparent to the end user. The results of MON3 analog-to-digital conversions are still stored/reported in the same memory locations (68h–69h, Lower Memory) regardless of whether the conversion was performed in fine mode or coarse mode. The only way to tell which mode generated the digital result is by reading the RSSIR bit. When the DS1874 is powered up, analog-to-digital conversions begin in a round-robin fashion. Every MON3 timeslice begins with a fine mode analog-to-digital conversion (using fine mode’s gain, offset, and right-shifting settings). See the flowchart in Figure 7 for more details. ______________________________________________________________________________________ 17 DS1874 SFP+ Controller with Digital LDD Interface Table 4. MON3 Hysteresis Threshold Values MON3 TIMESLICE NUMBER OF RIGHT-SHIFTS PERFORM FINEMODE CONVERSION DID PRIOR MON3 TIMESLICE RESULT IN A COARSE CONVERSION? (LAST RSSIR = 1?) Y N N WAS CURRENT FINEMODE CONVERSION ≥ 93.75% OF FS? FINE MODE MAX (hex) COARSE MODE MIN* (hex) 0 FFF8 F000 1 7FFC 7800 2 3FFE 3C00 3 1FFF 1E00 4 0FFF 0F00 5 07FF 0780 6 03FF 03C0 7 01FF 01E0 *This is the minimum reported coarse-mode conversion. Table 5. MON3 Configuration Registers DID CURRENT FINEMODE CONVERSION REACH MAX? Y Y PERFORM COARSEMODE CONVERSION N LAST RSSI = 0 REPORT FINE CONVERSION RESULT GAIN OFFSET RIGHT-SHIFT0 LAST RSSIR = 1 REPORT COARSE CONVERSION RESULT END OF MON3 TIMESLICE Figure 7. RSSI Flowchart Then, depending on whether the last MON3 timeslice resulted in a coarse-mode conversion and also depending on the value of the current fine conversion, decisions are made whether to use the current fine-mode conversion result or to make an additional conversion (within the same MON3 timeslice), using coarse mode (using coarse mode’s gain and offset settings and no rightshifting) and reporting the coarse-mode result. The flowchart in Figure 7 also illustrates how hysteresis is 18 REGISTER FINE MODE COARSE MODE 98h–99h, Table 02h 9Ch–9Dh, Table 02h A8h–A9h, Table 02h ACh–ADh, Table 02h 8Fh, Table 02h — CNFGC 8Bh, Table 02h UPDATE (RSSIR BIT) 6Fh, Lower Memory MON3 VALUE 68h–69h, Lower Memory implemented. The fine-mode conversion is compared to one of two thresholds. The actual threshold values are a function of the number of right-shifts being used. With the use of right-shifting, the fine mode full-scale is programmed to (1/2nth) of the coarse mode full-scale. The DS1874 now auto ranges to choose the range that gives the best resolution for the measurement. Hysteresis is applied to eliminate chatter when the input resides at the boundary of the two ranges. See Figure 7 for details. Table 4 shows the threshold values for each possible number of right-shifts. The RSSI_FF and RSSI_FC bits are used to force finemode or coarse-mode conversions, or to disable the dual-range functionality. Dual-range functionality is enabled by default (both RSSI_FC and RSSI_FF are factory programmed to 0 in EEPROM). It can be disabled by setting RSSI_FC to 0 and RSSI_FF to 1. These bits are also useful when calibrating MON3. For additional information, see Figure 19. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface is timed (within 500µs) to go to 0, at which point the part is fully functional. For all device addresses sourced from EEPROM (Table 02h, Register 8Ch), the default device address is A2h until VCC exceeds POA, allowing the device address to be recalled from the EEPROM. Power-On Analog (POA) POA holds the DS1874 in reset until VCC is at a suitable level (VCC > POA) for the device to accurately measure with its ADC and compare analog signals with its quicktrip monitors. Because VCC cannot be measured by the ADC when VCC is less than POA, POA also asserts the VCC LO alarm, which is cleared by a VCC ADC conversion greater than the customer-programmable V CC alarm low ADC limit. This allows a programmable limit to ensure that the headroom requirements of the transceiver are satisfied during a slow power-up. The TXF output does not latch until there is a conversion above VCC low limit. The POA alarm is nonmaskable. The TXF output is asserted when VCC is below POA. See the Low-Voltage Operation section for more information. Delta-Sigma Outputs (DAC1 and DAC2) Two delta-sigma outputs are provided, DAC1 and DAC2. With the addition of an external RC filter, these outputs provide two 9-bit resolution analog outputs with the full-scale range set by the input REFIN. Each output SEE RECALL SEE RECALL VPOA VCC VPOD SEE PRECHARGED TO 0 RECALLED VALUE PRECHARGED TO 0 RECALLED VALUE PRECHARGED TO 0 Figure 8. Low-Voltage Hysteresis Example ______________________________________________________________________________________ 19 DS1874 Low-Voltage Operation The DS1874 contains two power-on reset (POR) levels. The lower level is a digital POR (POD) and the higher level is an analog POR (POA). At startup, before the supply voltage rises above POA, the outputs are disabled, all SRAM locations are set to their defaults, shadowed EEPROM (SEE) locations are zero, and all analog circuitry is disabled. When VCC reaches POA, the SEE is recalled, and the analog circuitry is enabled. While VCC remains above POA, the device is in its normal operating state, and it responds based on its nonvolatile configuration. If during operation V CC falls below POA, but is still above POD, then the SRAM retains the SEE settings from the first SEE recall, but the device analog is shut down and the outputs disabled. If the supply voltage recovers back above POA, then the device immediately resumes normal operation. If the supply voltage falls below POD, then the device SRAM is placed in its default state and another SEE recall is required to reload the nonvolatile settings. The EEPROM recall occurs the next time VCC exceeds POA. Figure 8 shows the sequence of events as the voltage varies. Any time VCC is above POD, the I2C interface can be used to determine if VCC is below the POA level. This is accomplished by checking the RDYB bit in the STATUS (Lower Memory, Register 6Eh) byte. RDYB is set when VCC is below POA; when VCC rises above POA, RDYB DS1874 SFP+ Controller with Digital LDD Interface 3.24kΩ 3.24kΩ DAC1/DAC2 OUTPUT 0.01μF 0.01μF DS1874 is either manually controlled or controlled using a temperature-indexed LUT. A delta-sigma is a digital output using pulse-density modulation. It provides much lower output ripple than a standard digital PWM output given the same clock rate and filter components. Before tINIT, the DAC1 and DAC2 outputs are high impedance. The external RC filter components are chosen based on ripple requirements, output load, delta-sigma frequency, and desired response time. A recommended filter is shown in Figure 9. The DS1874’s delta-sigma outputs are 9 bits. For illustrative purposes, a 3-bit example is provided. Each possible output of this 3-bit delta-sigma DAC is given in Figure 10. Figure 9. Recommended RC Filter for DAC1/DAC2 0 1 In LUT mode, DAC1 and DAC2 are each controlled by a separate 8-bit, 4°C-resolution, temperature-addressed LUT. The delta-sigma outputs use a 9-bit structure. The 8-bit LUTs are either loaded directly into the MSBs (8:1) or the LSBs (7:0). This is determined by DAC1TI (Table 02h, Register C3h), DAC2TI (Table 02h, Register C4h), DAC1TC (Table 02h, Register C6h, bit 6), and DAC2TC (Table 02h, Register C6h, bit 5). See Figure 11 for more details. The DAC1 LUT (Table 07h) and DAC2 LUT (Table 08h) are nonvolatile and password-2 protected. The reference input, REFIN, is the supply voltage for the output buffer of DAC1 and DAC2. The voltage connected to REFIN must be able to support the edge rate requirements of the delta-sigma outputs. In a typical application, a 0.1µF capacitor should be connected between REFIN and ground. 2 3 4 5 6 7 Figure 10. Delta-Sigma Outputs DAC[1/2]TI DAC[1/2]TI 8 8 DAC[1/2]TC = 1 7 6 5 LUT LOADED TO [8:1] (DAC BIT 0 = 0) 4 LUT LOADED TO [7:0] 3 2 1 DELTA-SIGMA DACA OR DACB DELTA-SIGMA DACA OR DACB DAC[1/2]TC = 0 7 6 5 LUT LOADED TO [8:1] (DAC BIT 0 = 0) 4 LUT LOADED TO [7:0] 3 2 1 0 0 -40 +102 TEMPERATURE (°C) -40 +102 TEMPERATURE (°C) Figure 11. DAC1/DAC2 LUT Assignments 20 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface LOS, LOSOUT By default (LOSC = 1, Table 02h, Register 89h), the LOS pin is used to convert a standard comparator output for loss of signal (LOS) to an open-collector output. This means the mux shown in the Block Diagram by default selects the LOS pin as the source for the LOSOUT output transistor. The output of the mux can be read in the STATUS byte (Lower Memory, Register 6Eh) as the RXL bit. The RXL signal can be inverted (INV LOS = 1) before driving the open-drain output transistor using the XOR gate provided. Setting LOSC = 0 configures the mux to be controlled by LOS LO, which is driven by the output of the LOS quick trip (Table 02h, Registers BEh and BFh). The mux setting (stored in EEPROM) does not take effect until VCC > POA, allowing the EEPROM to recall. IN1, RSEL, OUT1, RSELOUT The digital input IN1 and RSEL pins primarily serve to meet the rate-select requirements of SFP and SFP+. They also serve as general-purpose inputs. OUT1 and RSELOUT are driven by a combination of the IN1, RSEL, and logic dictated by control registers in the EEPROM (Figure 13). The levels of IN1 and RSEL can be read using the STATUS register (Lower Memory, Register 6Eh). The open-drain output OUT1 can be controlled and/or inverted using the CNFGB register (Table 02h, Register 8Ah). The open-drain RSELOUT output is software-controlled and/or inverted through the Status register and CNFGA register (Table 02h, Register 89h). External pullup resistors must be provided on OUT1 and RSELOUT to realize high logic levels. TXF, TXD, TXDOUT TXDOUT is generated from a combination of TXF, TXD, and the internal signal FETG. A software control identical to TXD is available (TXDC, Lower Memory, Register 6Eh). A TXD pulse is internally extended (TXDEXT) by time tINITR1 to inhibit the latching of low alarms and warnings related to the APC loop to allow for the loop to stabilize. The nonlatching alarms and warnings are TXP LO, LOS LO, and MON1–MON4 LO alarms and warnings. In addition, TXP LO is disabled from creating FETG. TXF is both an input and an output (Figure 12). See the Transmit Fault (TXF) Output section for a detailed explanation of TXF. Figure 12 shows that the VCC RPU SET BIAS REGISTER TO 0 AND MAX3798/MAX3799 SET_IMOD TO 0 TXD TXDS TXD C TXDC R TXDIO Q TXDFG C D TXP HI FLAG TXDOUT FETG Q S TXDFLT TXP HI ENABLE TXF BIAS MAX TXF BIAS MAX ENABLE HBAL FLAG MINT HBAL FLAG TXP HI FLAG TXP LO FLAG BIAS MAX FLAG HBAL ENABLE TXP LO FLAG TXP LO ENABLE TXDEXT FAULT RESET TIMER (130ms) OUT IN IN POWER-ON RESET OUT Figure 12. Logic Diagram 1 ______________________________________________________________________________________ 21 DS1874 Digital I/O Pins Five digital input and five digital output pins are provided for monitoring and control. DS1874 SFP+ Controller with Digital LDD Interface IN1S OUT1 INVOUT1 IN1C IN1 RSELS RSELOUT RSELC Die Identification RSEL LOSC Transmit Fault (TXF) Output TXF can be triggered by all alarms, warnings, and quick trips (Figure 12). The six ADC alarms, warnings, and the LOS quick trips require enabling (Table 01h/05h, Registers F8h and FDh). See Figures 14a and 14b for nonlatched and latched operation. Latching of the alarms is controlled by the CNFGB and CNFGC registers (Table 02h, Registers 8Ah–8Bh). INV LOS LOSOUT LOS MUX LOS LO RXL Figure 13. Logic Diagram 2 same signals and faults can also be used to generate the internal signal FETG (Table 01h/05h, Registers FAh and FBh). FETG is used to send a fast “turn-off” command to the laser driver. The intended use is a direct connection to the MAX3798/MAX3799’s TXD input if this is desired. When V CC < POA, TXDOUT is high impedance. The DS1874 has an ID hardcoded in its die. Two registers (Table 02h, Registers CEh–CFh) are assigned for this feature. The CEh register reads 74h to identify the part as the DS1874, while the CFh register reads the current device version. 3-Wire Master for Controlling the MAX3798/MAX3799 The DS1874 controls the MAX3798/MAX3799 over a proprietary 3-wire interface. The DS1874 acts as the master, initiating communication with and generating the clock for the MAX3798/MAX3799. It is a 3-pin interface consisting of SDAOUT (a bidirectional data line), an SCLOUT clock signal, and a CSELOUT chip-select output (active high). Protocol The DS1874 initiates a data transfer by asserting the CSELOUT pin. It then starts to generate a clock signal DETECTION OF TXF FAULT TXF Figure 14a. TXF Nonlatched Operation DETECTION OF TXF FAULT TXD TXF Figure 14b. TXF Latched Operation 22 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface BIT NAME 15:9 Address 8 RWN 0: write; 1: read 7:0 Data 8-bit read or write data Figure 15 shows the 3-wire interface timing. Figure 16 shows the 3-wire state machine. See the 3-Wire Digital Interface Specification table for more information. DESCRIPTION DS1874 and MAX3798/MAX3799 Communication 7-bit internal register address Normal Operation Write Mode (RWN = 0): The master generates 16 clock cycles at SCLOUT in total. It outputs 16 bits (MSB first) to the SDAOUT line at the falling edge of the clock. The master closes the transmission by setting the CSELOUT to 0. Read Mode (RWN = 1): The master generates 16 clock cycles at SCLOUT in total. It outputs 8 bits (MSB first) to the SDAOUT line at the falling edge of the clock. The SDAOUT line is released after the RWN bit has been transmitted. The slave outputs 8 bits of data (MSB first) at the rising edge of the clock. The master samples SDAOUT at the falling edge of SCLOUT. The master closes the transmission by setting the CSELOUT to 0. The majority of the communication between the two devices consists of bias adjustments for the APC loop. After each temperature conversion, the laser modulation setting must be updated. Status registers TXSTAT1 and TXSTAT2 are read between temperature updates at a regular interval: t RR (see the Analog Voltage Monitoring Characteristics table). The results are stored in TXSTAT1 and TXSTAT2 (Table 02h, FCh–FDh). Manual Operation The MAX3798/MAX3799 are manually controllable using four registers in the DS1874: 3WCTRL, ADDRESS, WRITE, and READ. Commands can be manually issued while the DS1874 is in normal operation mode. It is also possible to suspend normal 3-wire commands so that only manual operation commands are sent (3WCTRL, Table 02h, Register F8h). WRITE MODE CSELOUT tL tT SCLOUT 0 1 2 3 4 5 6 7 8 9 A4 A3 A2 A1 A0 RWN D7 D6 10 11 12 13 14 15 tDS SDAOUT A6 A5 D5 D4 D3 D2 D1 D0 tDH READ MODE CSELOUT tL tT SCLOUT 0 1 2 3 4 5 6 7 A4 A3 A2 A1 A0 RWN 8 9 10 11 12 13 14 15 tDS SDAOUT A6 A5 D7 D6 D5 D4 D3 D2 D1 D0 tDH Figure 15. 3-Wire Timing ______________________________________________________________________________________ 23 DS1874 3-Wire Interface Timing after the CSELOUT has been set to 1. Each operation consists of 16-bit transfers (15-bit address/data, 1-bit RWN). All data transfers are MSB first. DS1874 SFP+ Controller with Digital LDD Interface RESET FLAGS HERE POR READ TXPOR1 UPDATE MODULATION YES READ TXPOR3 YES TX_POR = 1? TXDIS = 1? NO YES READ TXPOR4 SET TXD FLAG HERE TXD_LATCHED = 1 NO WRITE MOD, BIAS = 00 UPDATE CTRL TX_POR = = 1? TX_POR = = 1? NO TXD = = 0? TXD HIGH_STDBY 1011 NO START APC LOOP YES TXD = = 0? READ/WRITE MANMODE MAN_MODE_RDWR = 1? YES APC_BINARY = = 1? NO STROBE SET RTXPOR2_FLAG HERE TXD_FLAG = = 1 OR TXDIS = 1 OR RTXPOR2 FLAG NO READ TXPOR2 NO YES MODINC = = 1? NO BIASINC = = 1? YES INCREMENT MODULATION NO YES NO TX_POR = = 1? YES BIASINC = = 1? YES UPDATE BIAS YES BIASINC = = 1? YES NO APC_BINARY = = 1? NO NO STANDBY MODINC = 1? NO TXD_FLAG = = 1? OR RTXPOR2 FLAG = 1 NO TEMP_CONV_START = = 1? AND TXDIS = 0 UPDATE TXSTAT, BIAS, MOD MAN_MODE_RDWR = 1? Figure 16. 3-Wire State Machine 24 ______________________________________________________________________________________ YES SFP+ Controller with Digital LDD Interface The 3-wire control registers include the following: • RXCTRL1 • RXCTRL2 • SET_CML • SET_LOS • TXCTRL • IMODMAX • IBIASMAX • SET_PWCTRL • SET_TXDE The control registers are first written when VCC exceeds POA. They are also written if the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, bit 7). In the MAX3798/MAX3799, this bit is “sticky” (latches high and is cleared on a read). They are also updated on a rising edge of TXD. Any time one of these events occurs, the DS1874 reads and updates TXSTAT1 and TXSTAT2 and sets SET_IBIAS and SET_IMOD in the MAX3798/MAX3799 to 0. MAX3798/MAX3799 Register Map and DS1874 Corresponding Location MAX3798/MAX3799 REGISTER FUNCTION REGISTER NAME DS1874 LOCATION Receiver Control 1 RXCTRL1 Table 02h, E8h Receiver Control 2 RXCTRL2 Table 02h, E9h Receiver Status RXSTAT Lower Memory, 6Eh, Bit1 Output CML Level Setting SET_CML Table 02h, EAh LOS Threshold Level Setting SET_LOS Table 02h, EBh Transmitter Control TXCTRL Table 02h, ECh Transmitter Status 1 TXSTAT1 Table 02h, FCh Transmitter Status 2 TXSTAT2 Table 02h, FDh Bias Current Setting SET_IBIAS/BIAS Modulation Current Setting Table 02h, CBh–CCh SET_IMOD/MODULATION Table 02h, 82h–83h Maximum Modulation Current Setting IMODMAX Table 02h, EDh Maximum Bias Current Setting IBIASMAX Table 02h, EEh Modulation Current Increment Setting MODINC (see Note) Bias Current Increment Setting BIASINC Automatically performed by APC loop. Disable APC before using 3-wire manual mode. Manual Mode: Table 02h, F8h–FBh Mode Control MODECTRL (see Note) Transmitter Pulse-Width Control SET_PWCTRL Table 02h, EFh Transmitter Deemphasis Control SET_TXDE Table 02h, F0h Note: This register is not present in the DS1874. To access this register, use manual operation (see the Manual Operation section). ______________________________________________________________________________________ 25 DS1874 Initialization During initialization, the DS1874 transfers all its 3-wire EEPROM control registers to the MAX3798/MAX3799. DS1874 SFP+ Controller with Digital LDD Interface I2C Communication I2C Definitions The following terminology is commonly used to describe I2C data transfers. Master device: The master device controls the slave devices on the bus. The master device generates SCL clock pulses and START and STOP conditions. Slave devices: Slave devices send and receive data at the master’s request. Bus idle or not busy: Time between STOP and START conditions when both SDA and SCL are inactive and in their logic-high states. START condition: A START condition is generated by the master to initiate a new data transfer with a slave. Transitioning SDA from high to low while SCL remains high generates a START condition. See Figure 17 for applicable timing. STOP condition: A STOP condition is generated by the master to end a data transfer with a slave. Transitioning SDA from low to high while SCL remains high generates a STOP condition. See Figure 17 for applicable timing. Repeated START condition: The master can use a repeated START condition at the end of one data transfer to indicate that it will immediately initiate a new data transfer following the current one. Repeated STARTs are commonly used during read operations to identify a specific memory address to begin a data transfer. A repeated START condition is issued identically to a normal START condition. See Figure 17 for applicable timing. Bit write: Transitions of SDA must occur during the low state of SCL. The data on SDA must remain valid and unchanged during the entire high pulse of SCL plus the setup and hold time requirements (Figure 17). Data is shifted into the device during the rising edge of the SCL. Bit read: At the end a write operation, the master must release the SDA bus line for the proper amount of setup time (Figure 17) before the next rising edge of SCL during a bit read. The device shifts out each bit of data on SDA at the falling edge of the previous SCL pulse and the data bit is valid at the rising edge of the current SCL pulse. Remember that the master generates all SCL clock pulses, including when it is reading bits from the slave. Acknowledgement (ACK and NACK): An acknowledgement (ACK) or not acknowledge (NACK) is always the ninth bit transmitted during a byte transfer. The device receiving data (the master during a read or the slave during a write operation) performs an ACK by transmitting a zero during the ninth bit. A device performs a NACK by transmitting a one during the 9th bit. Timing (Figure 17) for the ACK and NACK is identical to all other bit writes. An ACK is the acknowledgment that the device is properly receiving data. A NACK is used to terminate a read SDA tBUF tF tHD:STA tLOW tSP SCL tHIGH tHD:STA tHD:DAT STOP tSU:STA tR START tSU:DAT REPEATED START NOTE: TIMING IS REFERENCED TO VIL(MAX) AND VIH(MIN). Figure 17. I2C Timing 26 ______________________________________________________________________________________ tSU:STO SFP+ Controller with Digital LDD Interface Byte write: A byte write consists of 8 bits of information transferred from the master to the slave (most significant bit first) plus a 1-bit acknowledgement from the slave to the master. The 8 bits transmitted by the master are done according to the bit-write definition and the acknowledgement is read using the bit-read definition. Byte read: A byte read is an 8-bit information transfer from the slave to the master plus a 1-bit ACK or NACK from the master to the slave. The 8 bits of information that are transferred (most significant bit first) from the slave to the master are read by the master using the bit-read definition, and the master transmits an ACK using the bit-write definition to receive additional data bytes. The master must NACK the last byte read to terminate communication so the slave returns control of SDA to the master. Slave address byte: Each slave on the I 2C bus responds to a slave address byte sent immediately following a START condition. The slave address byte contains the slave address in the most significant 7 bits and the R/W bit in the least significant bit. The DS1874 responds to two slave addresses. The auxiliary memory always responds to a fixed I2C slave address, A0h. The Lower Memory and Tables 00h–08h respond to I2C slave addresses that can be configured to any value between 00h–FEh using the DEVICE ADDRESS byte (Table 02h, Register 8Ch). The user also must set the ASEL bit (Table 02h, Register 89h) for this address to be active. By writing the correct slave address with R/W = 0, the master indicates it will write data to the slave. If R/W = 1, the master reads data from the slave. If an incorrect slave address is written, the DS1874 assumes the master is communicating with another I2C device and ignores the communications until the next START condition is sent. If the main device’s slave address is programmed to be A0h, access to the auxiliary memory is disabled. Memory address: During an I2C write operation to the DS1874, the master must transmit a memory address to identify the memory location where the slave is to store the data. The memory address is always the second byte transmitted during a write operation following the slave address byte. I2C Protocol Writing a single byte to a slave: The master must generate a START condition, write the slave address byte (R/W = 0), write the memory address, write the byte of data, and generate a STOP condition. Remember the master must read the slave’s acknowledgement during all byte-write operations. Writing multiple bytes to a slave: To write multiple bytes to a slave, the master generates a START condition, writes the slave address byte (R/W = 0), writes the memory address, writes up to 8 data bytes, and generates a STOP condition. The DS1874 writes 1 to 8 bytes (one page or row) with a single write transaction. This is internally controlled by an address counter that allows data to be written to consecutive addresses without transmitting a memory address before each data byte is sent. The address counter limits the write to one 8-byte page (one row of the memory map). Attempts to write to additional pages of memory without sending a STOP condition between pages results in the address counter wrapping around to the beginning of the present row. For example, a 3-byte write starts at address 06h and writes 3 data bytes (11h, 22h, and 33h) to three “consecutive” addresses. The result is that addresses 06h and 07h would contain 11h and 22h, respectively, and the third data byte, 33h, would be written to address 00h. To prevent address wrapping from occurring, the master must send a STOP condition at the end of the page, then wait for the bus-free or EEPROM write time to elapse. Then the master can generate a new START condition and write the slave address byte (R/W = 0) and the first memory address of the next memory row before continuing to write data. Acknowledge polling: Any time a EEPROM page is written, the DS1874 requires the EEPROM write time (tW) after the STOP condition to write the contents of the page to EEPROM. During the EEPROM write time, the DS1874 will not acknowledge its slave address because it is busy. It is possible to take advantage of that phenomenon by repeatedly addressing the DS1874, which allows the next page to be written as soon as the DS1874 is ready to receive the data. The alternative to acknowledge polling is to wait for maximum period of tW to elapse before attempting to write again to the DS1874. EEPROM write cycles: When EEPROM writes occur, the DS1874 writes the whole EEPROM memory page, even if only a single byte on the page was modified. Writes that do not modify all 8 bytes on the page are allowed and do not corrupt the remaining bytes of memory on the same page. Because the whole page is written, bytes on the page that were not modified during the transaction are still subject to a write ______________________________________________________________________________________ 27 DS1874 sequence or as an indication that the device is not receiving data. DS1874 SFP+ Controller with Digital LDD Interface TYPICAL I2C WRITE TRANSACTION MSB START 1 MSB LSB 0 1 0 0 0 SLAVE ADDRESS* 1 R/W SLAVE ACK b7 LSB b6 b5 b4 b3 b2 b1 MSB SLAVE ACK b0 b7 LSB b6 b5 b4 REGISTER ADDRESS READ/ WRITE b3 b2 b1 b0 SLAVE ACK STOP DATA *IF ASEL IS 0, THE SLAVE ADDRESS IS A0h FOR THE AUXILIARY MEMORY AND A2h FOR THE MAIN MEMORY. IF ASEL = 1, THE SLAVE ADDRESS IS DETERMINED BY TABLE 02h, REGISTER 8Ch FOR THE MAIN MEMORY. THE AUXILIARY MEMORY CONTINUES TO BE ADDRESSED AT A0h, EXCEPT WHEN THE PROGRAMMED ADDRESS FOR THE MAIN MEMORY IS A0h. EXAMPLE I2C TRANSACTIONS WITH A2h AS THE MAIN MEMORY DEVICE ADDRESS A2h A) SINGLE-BYTE WRITE -WRITE 00h TO REGISTER BAh B) SINGLE-BYTE READ -READ REGISTER BAh START 1 0 1 0 0 0 1 0 BAh 00h SLAVE SLAVE SLAVE 1 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 ACK ACK ACK A2h BAh START 1 0 1 0 0 0 1 0 SLAVE 1 0 1 1 1 0 1 0 SLAVE ACK ACK A2h C) TWO-BYTE WRITE -WRITE 01h AND 75h TO C8h AND C9h START 1 0 1 0 0 0 1 0 D) TWO-BYTE READ -READ C8h AND C9h START 1 0 1 0 0 0 1 0 A2h REPEATED START STOP A3h 1 0 1 0 0 0 1 1 SLAVE ACK DATA DATA IN BAh C8h 01h 75h SLAVE SLAVE SLAVE SLAVE 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 0 1 0 1 ACK ACK ACK ACK C8h SLAVE SLAVE 1 1 0 0 1 0 0 0 ACK ACK A3h REPEATED START 10100011 MASTER NACK STOP MASTER ACK DATA IN C9h STOP DATA SLAVE ACK DATA IN C8h DATA MASTER NACK STOP Figure 18. Example I2C Timing cycle. This can result in a whole page being worn out over time by writing a single byte repeatedly. Writing a page one byte at a time wears the EEPROM out eight times faster than writing the entire page at once. The DS1874’s EEPROM write cycles are specified in the Nonvolatile Memory Characteristics table. The specification shown is at the worst-case temperature. It can handle approximately ten times that many writes at room temperature. Writing to SRAMshadowed EEPROM memory with SEEB = 1 does not count as an EEPROM write cycle when evaluating the EEPROM’s estimated lifetime. Reading a single byte from a slave: Unlike the write operation that uses the memory address byte to define where the data is to be written, the read operation occurs at the present value of the memory address counter. To read a single byte from the slave, the master generates a START condition, writes the slave address byte with R/W = 1, reads the data byte with a NACK to indicate the end of the transfer, and generates a STOP condition. Manipulating the address counter for reads: A dummy write cycle can be used to force the address pointer to a particular value. To do this, the master generates a START condition, writes the slave 28 address byte (R/W = 0), writes the memory address where it desires to read, generates a repeated START condition, writes the slave address byte (R/W = 1), reads data with ACK or NACK as applicable, and generates a STOP condition. Memory Organization The DS1874 features nine separate memory tables that are internally organized into 8-byte rows. The Lower Memory is addressed from 00h to 7Fh and contains alarm and warning thresholds, flags, masks, several control registers, password entry area (PWE), and the table-select byte. Table 01h primarily contains user EEPROM (with PW1 level access) as well as alarm and warning-enable bytes. Table 02h is a multifunction space that contains configuration registers, scaling and offset values, passwords, interrupt registers as well as other miscellaneous control bytes. Table 04h contains a temperature-indexed LUT for control of the modulation voltage. The modulation LUT can be programmed in 2°C increments over the -40°C to +102°C range. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Many NV memory locations (listed within the Register Descriptions section) are actually shadowed EEPROM that are controlled by the SEEB bit in Table 02h, Register 80h. The DS1874 incorporates shadowed-EEPROM memory locations for key memory addresses that can be written many times. By default the shadowed-EEPROM bit, SEEB, is not set and these locations act as ordinary EEPROM. By setting SEEB, these locations function like SRAM cells, which allow an infinite number of write cycles without concern of wearing out the EEPROM. Setting SEEB also eliminates the requirement for the EEPROM write time, tW. Because changes made with SEEB enabled do not affect the EEPROM, these changes are not retained through power cycles. The power-on value is the last value written with SEEB disabled. This function can be used to limit the number of EEPROM writes during calibration or to change the monitor thresholds periodically during normal operation helping to reduce the number of times EEPROM is written. Figure 19 indicates which locations are shadowed EEPROM. Table 07h contains a temperature-indexed LUT for control of DAC1. The LUT has 36 entries that determine the DAC setting in 4°C windows between -40°C and +100°C. Table 08h contains a temperature-indexed LUT for control of DAC2. The LUT has 36 entries that determine the DAC setting in 4°C windows between -40°C and +100°C. Auxiliary Memory (device A0h) contains 256 bytes of EE memory accessible from address 00h–FFh. It is selected with the device address of A0h. See the Register Descriptions section for more complete details of each byte’s function, as well as for read/write permissions for each byte. I2C ADDRESS A0h 00h 00h LOWER MEMORY NOTE 1: IF ASEL = 0, THEN THE MAIN DEVICE I2C SLAVE ADDRESS IS A2h. IF ASEL = 1, THEN THE MAIN DEVICE I2C SLAVE ADDRESS IS DETERMINED BY THE VALUE IN TABLE 02h, REGISTER 8Ch. NOTE 2: TABLE 00h DOES NOT EXIST. NOTE 3: ALARM-ENABLE ROW CAN BE CONFIGURED TO EXIST AT TABLE 01h OR TABLE 05h USING THE MASK BIT IN TABLE 02h, REGISTER 89h. MAIN DEVICE EEPROM (256 BYTES) AUXILIARY DEVICE PASSWORD ENTRY (PWE) (4 BYTES) TABLE-SELECT BYTE 7Fh 80h 80h 80h TABLE 02h NONLOOKUP TABLE CONTROL AND CONFIGURATION REGISTERS TABLE 01h EEPROM (120 BYTES) E7h F7h F8h FFh ALARMENABLE ROW (8 BYTES) FFh E8h 3W CONFIG FFh 80h TABLE 06h TRACKING ERROR LOOKUP TABLE (36 BYTES) A3h TABLE 04h MOD LOOKUP TABLE (72 BYTES) 80h 80h TABLE 07h DAC1 LUT TABLE 08h DAC2 LUT A3h A3h C7h F8h TABLE 05h ALARM-ENABLE ROW (8 BYTES) FFh Figure 19. Memory Map ______________________________________________________________________________________ 29 DS1874 Shadowed EEPROM Table 05h is empty by default. It can be configured to contain the alarm- and warning-enable bytes from Table 01h, Registers F8h–FFh with the MASK bit enabled (Table 02h, Register 89h). In this case Table 01h is empty. Table 06h contains a temperature-indexed LUT that allows the APC set point to change as a function of temperature to compensate for tracking error (TE). The APC LUT has 36 entries that determine the APC setting in 4°C windows between -40°C and +100°C. DS1874 SFP+ Controller with Digital LDD Interface Register Descriptions The register maps show each byte/word (2 bytes) in terms of its row in the memory. The first byte in the row is located in memory at the row address (hexadecimal) in the leftmost column. Each subsequent byte on the row is one/two memory locations beyond the previous byte/word’s address. A total of 8 bytes are present on each row. For more information about each of these bytes see the corresponding register description. Lower Memory Register Map LOWER MEMORY WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME 00 THRESHOLD0 08 THRESHOLD1 VCC ALARM HI VCC ALARM LO VCC WARN HI VCC WARN LO 10 THRESHOLD2 MON1 ALARM HI MON1 ALARM LO MON1 WARN HI MON1 WARN LO 18 THRESHOLD3 MON2 ALARM HI MON2 ALARM LO MON2 WARN HI MON2 WARN LO 20 THRESHOLD4 MON3 ALARM HI MON3 ALARM LO MON3 WARN HI MON3 WARN LO 28 THRESHOLD5 MON4 ALARM HI MON4 ALARM LO MON4 WARN HI MON4 WARN LO 30–5F EEPROM EE ADC VALUES1 ALARM/ 70 WARN Read Access Write Access See each bit/byte separately TEMP ALARM LO EE BYTE 4/C BYTE 5/D BYTE 6/E TEMP WARN HI EE EE BYTE 7/F TEMP WARN LO EE EE EE MON1 VALUE MON2 VALUE MON3 VALUE MON4 VALUE RESERVED STATUS UPDATE ALARM2 ALARM3 ALARM1 ALARM0 RESERVED SELECT ACCESS CODE BYTE 3/B VCC VALUE TABLE 78 EE BYTE 2/A TEMP VALUE VALUES0 68 BYTE 1/9 TEMP ALARM HI ADC 60 30 BYTE 0/8 WARN3 PWE MSW RESERVED WARN2 RESERVED TBL PWE LSW SEL All All All PW2 All N/A PW1 PW2 N/A PW2 All PW2 N/A All All PW1 PW2 PW2 N/A PW1 All and PW2 + DS1874 mode hardware bit ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface TABLE 01h WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E BYTE 7/F 80–BF EEPROM EE EE EE EE EE EE EE EE C0–F7 EEPROM EE EE EE EE EE EE EE EE ALARM ALARM EN3 ALARM EN2 ALARM EN1 ALARM EN0 WARN EN3 WARN EN2 RESERVED RESERVED F8 ENABLE The ALARM ENABLE bytes (Registers F8h–FFh) can be configured to exist in Table 05h instead of here at Table 01h with the MASK bit (Table 02h, Register 89h). If the row is configured to exist in Table 05h, then these locations are empty in Table 01h. The access codes represent the factory default values of PW_ENA and PW_ENB (Table 02h, Registers C0h–C1h). ACCESS CODE Read Access Write Access See each bit/byte separately All All All PW2 All N/A PW1 PW2 N/A PW2 All PW2 N/A All All PW1 PW2 PW2 N/A PW1 All and PW2 + DS1874 mode hardware bit ______________________________________________________________________________________ 31 DS1874 Table 01h Register Map DS1874 SFP+ Controller with Digital LDD Interface Table 02h Register Map TABLE 02h ROW (hex) ROW NAME WORD 0 BYTE 0/8 WORD 1 BYTE 1/9 BYTE 2/A WORD 2 BYTE 3/B BYTE 4/C MODULATION WORD 3 BYTE 5/D BYTE 6/E 80 CONFIG0 MODE TINDEX 88 CONFIG1 SAMPLE RATE CNFGA 90 SCALE0 RESERVED VCC SCALE MON1 SCALE MON2 SCALE 98 SCALE1 MON3 FINE SCALE MON4 SCALE MON3 COARSE SCALE RESERVED A0 OFFSET0 RESERVED VCC OFFSET MON1 OFFSET MON2 OFFSET A8 OFFSET1 B0 PWD VALUE B8 THRESHOLD PWD C0 ENABLE APC C8 D0 HI BIAS D8–E7 E8 LUT EMPTY 3W CONFIG0 3W F0 CONFIG1 3W CONFIG2 F8 DAC1 VALUE BYTE 7/F REGISTER CNFGB DEVICE ADDRESS CNFGC RESERVED DAC2 VALUE RSHIFT0 RSHIFT1 MON3 FINE OFFSET MON4 OFFSET MON3 COARSE OFFSET INTERNAL TEMP OFFSET* PW1 MSW PW1 LSW PW2 MSW PW2 LSW LOS RANGING COMP RANGING RESERVED ISTEP HTXP LTXP HLOS LLOS PW_ENA PW_ENB MODTI DAC1TI DAC2TI RESERVED LUTTC TBLSELPON MAN_ MAN BIAS CNTL BIAS REGISTER APC DEVICE DEVICE DAC ID VER HBATH HBATH HBATH HBATH HBATH HBATH HBATH HBATH EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY RXCTRL1 RXCTRL2 SETCML SETLOS TXCTRL IMODMAX IBIASMAX SETPWCTRL SETTXDE RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED 3WCTRL ADDRESS WRITE READ TXSTAT1 TXSTAT2 RESERVED RESERVED *The final result must be XORed with BB40h before writing to this register. ACCESS CODE Read Access Write Access 32 See each bit/byte separately All All All PW2 All N/A PW1 PW2 N/A PW2 All PW2 N/A All and DS1874 hardware PW2 + mode bit All All PW1 PW2 PW2 N/A PW1 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface TABLE 04h (MODULATION LUT) WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E BYTE 7/F 80–C7 LUT4 MOD MOD MOD MOD MOD MOD MOD MOD Table 05h Register Map TABLE 05h ROW (hex) 80–F7 F8 WORD 0 ROW NAME BYTE 0/8 WORD 1 BYTE 1/9 BYTE 2/A WORD 2 WORD 3 BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E BYTE 7/F EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY EMPTY ALARM ALARM EN3 ALARM EN2 ALARM EN1 ALARM EN0 WARN EN3 WARN EN2 RESERVED RESERVED ENABLE Table 05h is empty by default. It can be configured to contain the alarm and warning-enable bytes from Table 01h, Registers F8h–FFh with the MASK bit enabled (Table 02h, Register 89h). In this case Table 01h is empty. Table 06h Register Map TABLE 06h (APC LUT) WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E 80–9F LUT6 APC REF APC REF APC REF APC REF APC REF APC REF APC REF APC REF A0 LUT6 APC REF APC REF APC REF APC REF RESERVED RESERVED RESERVED RESERVED BYTE 7/F The access codes represent the factory default values of PW_ENA and PW_ENB (Table 02h, Registers C0h–C1h). ACCESS CODE Read Access Write Access See each bit/byte separately All All All PW2 All N/A PW1 PW2 N/A PW2 All PW2 N/A All and DS1874 hardware PW2 + mode bit All All PW1 PW2 PW2 N/A PW1 ______________________________________________________________________________________ 33 DS1874 Table 04h Register Map DS1874 SFP+ Controller with Digital LDD Interface Table 07h Register Map TABLE 07h (DAC1 LUT) WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E 80–9F LUT7 DAC1 DAC1 DAC1 DAC1 DAC1 DAC1 DAC1 DAC1 A0 LUT7 DAC1 DAC1 DAC1 DAC1 RESERVED RESERVED RESERVED RESERVED BYTE 7/F Table 08h Register Map TABLE 08h (DAC2 LUT) WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME 80–9F LUT8 DAC2 DAC2 DAC2 DAC2 DAC2 DAC2 DAC2 DAC2 A0 LUT8 DAC2 DAC2 DAC2 DAC2 RESERVED RESERVED RESERVED RESERVED BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E BYTE 7/F Auxiliary A0h Memory Register Map AUXILIARY MEMORY (A0h) WORD 0 WORD 1 WORD 2 WORD 3 ROW (hex) ROW NAME BYTE 0/8 BYTE 1/9 BYTE 2/A BYTE 3/B BYTE 4/C BYTE 5/D BYTE 6/E BYTE 7/F 00–FF AUX EE EE EE EE EE EE EE EE EE The access codes represent the factory default values of PW_ENA and PW_ENB (Table 02h, Registers C0h–C1h). ACCESS CODE Read Access Write Access 34 See each bit/byte separately All All All PW2 All N/A PW1 PW2 N/A PW2 All PW2 N/A All and DS1874 hardware PW2 + mode bit All All PW1 PW2 PW2 N/A PW1 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Lower Memory, Register 00h–01h: TEMP ALARM HI Lower Memory, Register 04h–05h: TEMP WARN HI FACTORY DEFAULT 7FFFh READ ACCESS All WRITE ACCESS PW2 or (PW1 and WLOWER) MEMORY TYPE Nonvolatile (SEE) 00h, 04h S 26 25 24 23 22 21 20 01h, 05h 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 BIT 7 BIT 0 Temperature measurement updates above this two’s complement threshold set corresponding alarm or warning bits. Temperature measurement updates equal to or below this threshold clear alarm or warning bits. Lower Memory, Register 02h–03h: TEMP ALARM LO Lower Memory, Register 06h–07h: TEMP WARN LO FACTORY DEFAULT 8000h READ ACCESS All WRITE ACCESS PW2 or (PW1 and WLOWER) MEMORY TYPE Nonvolatile (SEE) 02h, 06h S 26 25 24 23 22 21 20 03h, 07h 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 BIT 7 BIT 0 Temperature measurement updates below this two’s complement threshold set corresponding alarm or warning bits. Temperature measurement updates equal to or above this threshold clear alarm or warning bits. ______________________________________________________________________________________ 35 DS1874 Lower Memory Register Descriptions DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 08h–09h: VCC ALARM HI Lower Memory, Register 0Ch–0Dh: VCC WARN HI Lower Memory, Register 10h–11h: MON1 ALARM HI Lower Memory, Register 14h–15h: MON1 WARN HI Lower Memory, Register 18h–19h: MON2 ALARM HI Lower Memory, Register 1Ch–1Dh: MON2 WARN HI Lower Memory, Register 20h–21h: MON3 ALARM HI Lower Memory, Register 24h–25h: MON3 WARN HI Lower Memory, Register 28h–29h: MON4 ALARM HI Lower Memory, Register 2Ch–2Dh: MON4 WARN HI 08h, 0Ch, 10h, 14h, 18h, 1Ch, 20h, 24h, 28h, 2Ch 09h, 0Dh, 11h, 15h, 19h, 1Dh, 21h, 25h, 29h, 2Dh FACTORY DEFAULT FFFFh READ ACCESS All WRITE ACCESS PW2 or (PW1 and WLOWER) MEMORY TYPE Nonvolatile (SEE) 215 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 BIT 7 BIT 0 Voltage measurement updates above this unsigned threshold set corresponding alarm or warning bits. Voltage measurements equal to or below this threshold clear alarm or warning bits. 36 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface 0Ah, 0Eh, 12h, 16h, 1Ah, 1Eh, 22h, 26h, 2Ah, 2Eh 0Bh, 0Fh, 13h, 17h, 1Bh, 1Fh, 23h, 27h, 2Bh, 2Fh DS1874 Lower Memory, Register 0Ah–0Bh: VCC ALARM LO Lower Memory, Register 0Eh–0Fh: VCC WARN LO Lower Memory, Register 12h–13h: MON1 ALARM LO Lower Memory, Register 16h–17h: MON1 WARN LO Lower Memory, Register 1Ah–1Bh: MON2 ALARM LO Lower Memory, Register 1Eh–1Fh: MON2 WARN LO Lower Memory, Register 22h–23h: MON3 ALARM LO Lower Memory, Register 26h–27h: MON3 WARN LO Lower Memory, Register 2Ah–2Bh: MON4 ALARM LO Lower Memory, Register 2Eh–2Fh: MON4 WARN LO FACTORY DEFAULT 0000h READ ACCESS All WRITE ACCESS PW2 or (PW1 and WLOWER) MEMORY TYPE Nonvolatile (SEE) 215 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 BIT 7 BIT 0 Voltage measurement updates below this unsigned threshold set corresponding alarm or warning bits. Voltage measurements equal to or above this threshold clear alarm or warning bits. ______________________________________________________________________________________ 37 DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 30h–5Fh: EE 30h to 5Fh FACTORY DEFAULT 00h READ ACCESS All WRITE ACCESS PW2 or (PW1 and WLOWER) MEMORY TYPE Nonvolatile (EE) EE EE EE EE EE EE EE BIT 7 EE BIT 0 PW2 level access-controlled EEPROM. Lower Memory, Register 60h–61h: TEMP VALUE POWER-ON VALUE 0000h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile 60h S 26 25 24 23 22 21 20 61h 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 BIT 7 Signed two’s complement direct-to-temperature measurement. 38 ______________________________________________________________________________________ BIT 0 SFP+ Controller with Digital LDD Interface DS1874 Lower Memory, Register 62h–63h: VCC VALUE Lower Memory, Register 64h–65h: MON1 VALUE Lower Memory, Register 66h–67h: MON2 VALUE Lower Memory, Register 68h–69h: MON3 VALUE Lower Memory, Register 6Ah–6Bh: MON4 VALUE 62h, 64h, 66h, 68h, 6Ah 63h, 65h, 67h, 69h, 6Bh POWER-ON VALUE 0000h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile 215 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 BIT 7 BIT 0 Left-justified unsigned voltage measurement. Lower Memory, Register 6Ch–6Dh: RESERVED POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE 6Ch, 6Dh 0 0 0 0 BIT 7 0 0 0 0 BIT 0 These registers are reserved. The value when read is 00h. ______________________________________________________________________________________ 39 DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 6Eh: STATUS Write Access 6Eh POWER-ON VALUE X0XX 0XXXb READ ACCESS All WRITE ACCESS See below MEMORY TYPE Volatile N/A All N/A All All N/A N/A N/A TXDS TXDC IN1S RSELS RSELC TXF RXL RDYB BIT 7 40 BIT 0 BIT 7 TXDS: TXD Status Bit. Reflects the logic state of the TXD pin (read only). 0 = TXD pin is logic-low. 1 = TXD pin is logic-high. BIT 6 TXDC: TXD Software Control Bit. This bit allows for software control that is identical to the TXD pin. See the section on TXD for further information. Its value is wire-ORed with the logic value of the TXD pin (writable by all users). 0 = (Default). 1 = Forces the device into a TXD state regardless of the value of the TXD pin. BIT 5 IN1S: IN1 Status Bit. Reflects the logic state of the IN1 pin (read only). 0 = IN1 pin is logic-low. 1 = IN1 pin is logic-high. BIT 4 RSELS: RSEL Status Bit. Reflects the logic state of the RSEL pin (read only). 0 = RSEL pin is logic-low. 1 = RSEL pin is logic-high. BIT 3 RSELC: RSEL Software Control Bit. This bit allows for software control that is identical to the RSEL pin. Its value is wire-ORed with the logic value of the RSEL pin to create the RSELOUT pin’s logic value (writable by all users). 0 = (Default). 1 = Forces the device into a RSEL state regardless of the value of the RSEL pin. BIT 2 TXF: Reflects the driven state of the TXF pin (read only). 0 = TXF pin is driven low. 1 = TXF pin is pulled high. BIT 1 RXL: Reflects the driven state of the LOSOUT pin (read only). 0 = LOSOUT pin is driven low. 1 = LOSOUT pin is pulled high. BIT 0 RDYB: Ready Bar. 0 = VCC is above POA. 1 = VCC is below POA and/or too low to communicate over the I2C bus. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface 6Fh POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS All and DS1874 Hardware MEMORY TYPE Volatile TEMP RDY VCC RDY MON1 RDY MON2 RDY DS1874 Lower Memory, Register 6Fh: UPDATE MON3 RDY MON4 RDY BIT 7 BITS 7:2 RESERVED RSSIR BIT 0 Update of completed conversions. At power-on, these bits are cleared and are set as each conversion is completed. These bits can be cleared so that a completion of a new conversion is verified. BIT 1 RESERVED BIT 0 RSSIR: RSSI Range. Reports the range used for conversion update of MON3. 0 = Fine range is the reported value. 1 = Coarse range is the reported value. ______________________________________________________________________________________ 41 DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 70h: ALARM3 70h POWER-ON VALUE 10h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile TEMP HI TEMP LO VCC HI VCC LO MON1 HI MON1 LO MON2 HI BIT 7 42 MON2 LO BIT 0 BIT 7 TEMP HI: High-alarm status for temperature measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 6 TEMP LO: Low-alarm status for temperature measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 5 VCC HI: High-alarm status for VCC measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 4 VCC LO: Low-alarm status for VCC measurement. This bit is set when the VCC supply is below the POA trip point value. It clears itself when a VCC measurement is completed and the value is above the low threshold. 0 = Last measurement was equal to or above threshold setting. 1 = (Default) Last measurement was below threshold setting. BIT 3 MON1 HI: High-alarm status for MON1 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 2 MON1 LO: Low-alarm status for MON1 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 1 MON2 HI: High-alarm status for MON2 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 0 MON2 LO: Low-alarm status for MON2 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface 71h POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile MON3 HI MON3 LO MON4 HI DS1874 Lower Memory, Register 71h: ALARM2 MON4 LO RESERVED RESERVED RESERVED BIT 7 BIT 0 BIT 7 MON3 HI: High-alarm status for MON3 measurement. A TXD event does not clear this alarm. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 6 MON3 LO: Low-alarm status for MON3 measurement. A TXD event does not clear this alarm. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 5 MON4 HI: High-alarm status for MON4 measurement. A TXD event does not clear this alarm. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 4 MON4 LO: Low-alarm status for MON4 measurement. A TXD event does not clear this alarm. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BITS 3:1 BIT 0 TXFINT RESERVED TXFINT: TXF Interrupt. This bit is the wire-ORed logic of all alarms and warnings wire-ANDed with their corresponding enable bits in addition to nonmaskable alarms TXP HI, TXP LO, BIAS MAX, and HBAL. The enable bits are found in Table 01h, Registers F8h–FFh. ______________________________________________________________________________________ 43 DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 72h: ALARM1 72h POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile RESERVED RESERVED RESERVED RESERVED HBAL RESERVED TXP HI TXP LO BIT 7 BITS 7:4 BIT 0 RESERVED BIT 3 HBAL: High-Bias Alarm Status; Fast Comparison. A TXD event clears this alarm. 0 = (Default) Last comparison was below threshold setting. 1 = Last comparison was above threshold setting. BIT 2 RESERVED BIT 1 TXP HI: High-Alarm Status TXP; Fast Comparison. A TXD event clears this alarm. 0 = (Default) Last comparison was below threshold setting. 1 = Last comparison was above threshold setting. BIT 0 TXP LO: Low-Alarm Status TXP; Fast Comparison. A TXD event clears this alarm. 0 = (Default) Last comparison was above threshold setting. 1 = Last comparison was below threshold setting. Lower Memory, Register 73h: ALARM0 73h POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile LOS HI LOS LO RESERVED RESERVED BIAS MAX RESERVED RESERVED RESERVED BIT 7 BIT 7 LOS HI: High-Alarm Status for MON3; Fast Comparison. A TXD event does not clear this alarm. 0 = (Default) Last comparison was below threshold setting. 1 = Last comparison was above threshold setting. BIT 6 LOS LO: Low-Alarm Status for MON3; Fast Comparison. A TXD event does not clear this alarm. 0 = (Default) Last comparison was above threshold setting. 1 = Last comparison was below threshold setting. BITS 5:4 BIT 3 BITS 2:0 44 BIT 0 RESERVED BIAS MAX: Alarm status for maximum digital setting of BIAS. A TXD event clears this alarm. 0 = (Default) The value for BIAS is equal to or below the IBIASMAX register. 1 = Requested value for BIAS is greater than the IBIASMAX register. RESERVED ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface 74h POWER-ON VALUE 10h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile TEMP HI TEMP LO VCC HI DS1874 Lower Memory, Register 74h: WARN3 VCC LO MON1 HI MON1 LO BIT 7 MON2 HI MON2 LO BIT 0 BIT 7 TEMP HI: High-warning status for temperature measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 6 TEMP LO: Low-warning status for temperature measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 5 VCC HI: High-warning status for VCC measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 4 VCC LO: Low-warning status for VCC measurement. This bit is set when the VCC supply is below the POA trip point value. It clears itself when a VCC measurement is completed and the value is above the low threshold. 0 = Last measurement was equal to or above threshold setting. 1 = (Default) Last measurement was below threshold setting. BIT 3 MON1 HI: High-warning status for MON1 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 2 MON1 LO: Low-warning status for MON1 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 1 MON2 HI: High-warning status for MON2 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 0 MON2 LO: Low-warning status for MON2 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. ______________________________________________________________________________________ 45 DS1874 SFP+ Controller with Digital LDD Interface Lower Memory, Register 75h: WARN2 75h POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE Volatile MON3 HI MON3 LO MON4 HI MON4 LO RESERVED RESERVED RESERVED BIT 7 BIT 0 BIT 7 MON3 HI: High-warning status for MON3 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 6 MON3 LO: Low-warning status for MON3 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BIT 5 MON4 HI: High-warning status for MON4 measurement. 0 = (Default) Last measurement was equal to or below threshold setting. 1 = Last measurement was above threshold setting. BIT 4 MON4 LO: Low-warning status for MON4 measurement. 0 = (Default) Last measurement was equal to or above threshold setting. 1 = Last measurement was below threshold setting. BITS 3:0 RESERVED Lower Memory, Register 76h–7Ah: RESERVED MEMORY POWER-ON VALUE 00h READ ACCESS All WRITE ACCESS N/A MEMORY TYPE These registers are reserved. The value when read is 00h. 46 RESERVED ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface POWER-ON VALUE FFFF FFFFh READ ACCESS N/A WRITE ACCESS All MEMORY TYPE Volatile DS1874 Lower Memory, Register 7Bh–7Eh: Password Entry (PWE) 7Bh 231 230 229 228 227 226 225 224 7Ch 223 222 221 220 219 218 217 216 7Dh 215 214 213 212 211 210 29 28 7Eh 27 26 25 24 23 22 21 20 BIT 7 BIT 0 There are two passwords for the DS1874. Each password is 4 bytes long. The lower level password (PW1) has all the access of a normal user plus those made available with PW1. The higher level password (PW2) has all the access of PW1 plus those made available with PW2. The values of the passwords reside in EEPROM inside PW2 memory. At power-up, all PWE bits are set to 1. All reads at this location are 0. Lower Memory, Register 7Fh: Table Select (TBL SEL) 7Fh POWER-ON VALUE TBLSELPON (Table 02h, Register C7h) READ ACCESS All WRITE ACCESS All MEMORY TYPE Volatile 27 BIT 7 26 25 24 23 22 21 20 BIT 0 The upper memory tables of the DS1874 are accessible by writing the desired table value in this register. The power-on value of this register is defined by the value written to TBLSELPON (Table 02h, Register C7h). ______________________________________________________________________________________ 47 DS1874 SFP+ Controller with Digital LDD Interface Table 01h Register Descriptions Table 01h, Register 80h–BFh: EEPROM 80h–BFh POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1A) or (PW1 and RTBL1A) WRITE ACCESS PW2 or (PW1 and RWTBL1A) MEMORY TYPE Nonvolatile (EE) EE EE EE EE EE EE EE BIT 7 EE BIT 0 EEPROM for PW1 and/or PW2 level access. Table 01h, Register C0h–F7h: EEPROM C0h–F7h POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1B) or (PW1 and RTBL1B) WRITE ACCESS PW2 or (PW1 and RWTBL1B) MEMORY TYPE Nonvolatile (EE) EE EE EE EE EE EE EE BIT 7 EEPROM for PW1 and/or PW2 level access. 48 ______________________________________________________________________________________ EE BIT 0 SFP+ Controller with Digital LDD Interface F8h POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) TEMP HI TEMP LO VCC HI VCC LO BIT 7 MON1 HI MON1 LO DS1874 Table 01h, Register F8h: ALARM EN3 MON2 HI MON2 LO BIT 0 Layout is identical to ALARM3 in Lower Memory, Register 70h. Enables alarms to create TXFINT (Lower Memory, Register 71h) logic. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BIT 7 TEMP HI: 0 = Disables interrupt from TEMP HI alarm. 1 = Enables interrupt from TEMP HI alarm. BIT 6 TEMP LO: 0 = Disables interrupt from TEMP LO alarm. 1 = Enables interrupt from TEMP LO alarm. BIT 5 VCC HI: 0 = Disables interrupt from VCC HI alarm. 1 = Enables interrupt from VCC HI alarm. BIT 4 VCC LO: 0 = Disables interrupt from VCC LO alarm. 1 = Enables interrupt from VCC LO alarm. BIT 3 MON1 HI: 0 = Disables interrupt from MON1 HI alarm. 1 = Enables interrupt from MON1 HI alarm. BIT 2 MON1 LO: 0 = Disables interrupt from MON1 LO alarm. 1 = Enables interrupt from MON1 LO alarm. BIT 1 MON2 HI: 0 = Disables interrupt from MON2 HI alarm. 1 = Enables interrupt from MON2 HI alarm. BIT 0 MON2 LO: 0 = Disables interrupt from MON2 LO alarm. 1 = Enables interrupt from MON2 LO alarm. ______________________________________________________________________________________ 49 DS1874 SFP+ Controller with Digital LDD Interface Table 01h, Register F9h: ALARM EN2 F9h POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) MON3 HI MON3 LO MON4 HI MON4 LO RESERVED RESERVED RESERVED BIT 7 RESERVED BIT 0 Layout is identical to ALARM2 in Lower Memory, Register 71h. Enables alarms to create TXFINT (Lower Memory, Register 71h) logic. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BIT 7 MON3 HI: 0 = Disables interrupt from MON3 HI alarm. 1 = Enables interrupt from MON3 HI alarm. BIT 6 MON3 LO: 0 = Disables interrupt from MON3 LO alarm. 1 = Enables interrupt from MON3 LO alarm. BIT 5 MON4 HI: 0 = Disables interrupt from MON4 HI alarm. 1 = Enables interrupt from MON4 HI alarm. BIT 4 MON4 LO: 0 = Disables interrupt from MON4 LO alarm. 1 = Enables interrupt from MON4 LO alarm. BIT 3:0 50 RESERVED ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface FAh POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) RESERVED RESERVED RESERVED RESERVED BIT 7 HBAL RESERVED DS1874 Table 01h, Register FAh: ALARM EN1 TXP HI TXP LO BIT 0 Layout is identical to ALARM1 in Lower Memory, Register 72h. Enables alarms to create internal signal FETG (see Figure 12) logic. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BITS 7:4 RESERVED BIT 3 HBAL: 0 = Disables interrupt from HBAL alarm. 1 = Enables interrupt from HBAL alarm. BIT 2 RESERVED BIT 1 TXP HI: 0 = Disables interrupt from TXP HI alarm. 1 = Enables interrupt from TXP HI alarm. BIT 0 TXP LO: 0 = Disables interrupt from TXP LO alarm. 1 = Enables interrupt from TXP LO alarm. ______________________________________________________________________________________ 51 DS1874 SFP+ Controller with Digital LDD Interface Table 01h, Register FBh: ALARM EN0 FBh POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) LOS HI LOS LO RESERVED RESERVED BIAS MAX RESERVED RESERVED BIT 7 RESERVED BIT 0 Layout is identical to ALARM0 in Lower Memory, Register 73h. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BIT 7 LOS HI: Enables alarm to create TXFINT (Lower Memory, Register 71h) logic. 0 = Disables interrupt from LOS HI alarm. 1 = Enables interrupt from LOS HI alarm. BIT 6 LOS LO: Enables alarm to create TXFINT (Lower Memory, Register 71h) logic. 0 = Disables interrupt from LOS LO alarm. 1 = Enables interrupt from LOS LO alarm. BITS 5:4 BIT 3 BITS 2:0 52 RESERVED BIAS MAX: Enables alarm to create internal signal FETG (see Figure 12) logic. 0 = Disables interrupt from BIAS MAX alarm. 1 = Enables interrupt from BIAS MAX alarm. RESERVED ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface F8h POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) TEMP HI TEMP LO VCC HI VCC LO MON1 HI BIT 7 MON1 LO DS1874 Table 01h, Register FCh: WARN EN3 MON2 HI MON2 LO BIT 0 Layout is identical to WARN3 in Lower Memory, Register 74h. Enables warnings to create TXFINT (Lower Memory, Register 71h) logic. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BIT 7 TEMP HI: 0 = Disables interrupt from TEMP HI warning. 1 = Enables interrupt from TEMP HI warning. BIT 6 TEMP LO: 0 = Disables interrupt from TEMP LO warning. 1 = Enables interrupt from TEMP LO warning. BIT 5 VCC HI: 0 = Disables interrupt from VCC HI warning. 1 = Enables interrupt from VCC HI warning. BIT 4 VCC LO: 0 = Disables interrupt from VCC LO warning. 1 = Enables interrupt from VCC LO warning. BIT 3 MON1 HI: 0 = Disables interrupt from MON1 HI warning. 1 = Enables interrupt from MON1 HI warning. BIT 2 MON1 LO: 0 = Disables interrupt from MON1 LO warning. 1 = Enables interrupt from MON1 LO warning. BIT 1 MON2 HI: 0 = Disables interrupt from MON2 HI warning. 1 = Enables interrupt from MON2 HI warning. BIT 0 MON2 LO: 0 = Disables interrupt from MON2 LO warning. 1 = Enables interrupt from MON2 LO warning. ______________________________________________________________________________________ 53 DS1874 SFP+ Controller with Digital LDD Interface Table 01h, Register FDh: WARN EN2 F9h POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) MON3 HI MON3 LO MON4 HI MON4 LO RESERVED RESERVED RESERVED BIT 7 RESERVED BIT 0 Layout is identical to WARN2 in Lower Memory, Register 75h. Enables warnings to create TXFINT (Lower Memory, Register 71h) logic. The MASK bit (Table 02h, Register 89h) determines whether this memory exists in Table 01h or 05h. BIT 7 MON3 HI: 0 = Disables interrupt from MON3 HI warning. 1 = Enables interrupt from MON3 HI warning. BIT 6 MON3 LO: 0 = Disables interrupt from MON3 LO warning. 1 = Enables interrupt from MON3 LO warning. BIT 5 MON4 HI: 0 = Disables interrupt from MON4 HI warning. 1 = Enables interrupt from MON4 HI warning. BIT 4 MON4 LO: 0 = Disables interrupt from MON4 LO warning. 1 = Enables interrupt from MON4 LO warning. BITS 3:0 RESERVED Table 01h, Register FEh–FFh: RESERVED POWER-ON VALUE 00h READ ACCESS PW2 or (PW1 and RWTBL1C) or (PW1 and RTBL1C) WRITE ACCESS PW2 or (PW1 and RWTBL1C) MEMORY TYPE Nonvolatile (SEE) These registers are reserved. 54 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Table 02h, Register 80h: MODE 80h POWER-ON VALUE 3Fh READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RTBL246) MEMORY TYPE Volatile SEEB RESERVED BIT 7 DAC1 EN DAC2 EN AEN MOD EN APC EN BIAS EN BIT 0 BIT 7 SEEB: 0 = (Default) Enables EEPROM writes to SEE bytes. 1 = Disables EEPROM writes to SEE bytes during configuration, so that the configuration of the part is not delayed by the EE cycle time. Once the values are known, write this bit to a 0 and write the SEE locations again for data to be written to the EEPROM. BIT 6 RESERVED BIT 5 BIT 4 BIT 3 BIT 2 DAC1 EN: 0 = DAC1 VALUE is writable by the user and the LUT recalls are disabled. This allows users to interactively test their modules by writing the values for DAC1. The output is updated with the new value at the end of the write cycle. The I2C STOP condition is the end of the write cycle. 1 = (Default) Enables auto control of the LUT for DAC1 VALUE. DAC2 EN: 0 = DAC2 VALUE is writable by the user and the LUT recalls are disabled. This allows users to interactively test their modules by writing the values for DAC2. The output is updated with the new value at the end of the write cycle. The I2C STOP condition is the end of the write cycle. 1 = (Default) Enables auto control of the LUT for DAC2 VALUE. AEN: 0 = The temperature-calculated index value TINDEX is writable by users and the updates of calculated indexes are disabled. This allows users to interactively test their modules by controlling the indexing for the LUTs. The recalled values from the LUTs appear in the DAC registers after the next completion of a temperature conversion. MOD EN: 0 = Modulation is writable by the user and the LUT recalls are disabled. This allows users to interactively test their modules by writing the DAC value for modulation. The output is updated with the new value at the end of the write cycle. The I2C STOP condition is the end of the write cycle. 1 = (Default) Enables auto control of the LUT for modulation. BIT 1 APC EN: 0 = APC DAC is writable by the user and the LUT recalls are disabled. This allows users to interactively test their modules by writing the DAC value for APC reference. The output is updated with the new value at the end of the write cycle through the 3-wire interface. The I2C STOP condition is the end of the write cycle. 1 = (Default) Enables auto control of the LUT for APC reference. BIT 0 BIAS EN: 0 = BIAS register is controlled by the user and the APC is in manual mode. The BIAS register value is written with the use of the 3-wire interface. This allows the user to interactively test their modules by writing the DAC value for bias. 1 = (Default) Enables auto control for the APC feedback. ______________________________________________________________________________________ 55 DS1874 Table 02h Register Descriptions DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register 81h: Temperature Index (TINDEX) 81h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and AEN = 0) or (PW1 and RWTBL246 and AEN = 0) MEMORY TYPE Volatile 27 26 25 24 23 22 21 BIT 7 20 BIT 0 Holds the calculated index based on the temperature measurement. This index is used for the address during lookup of Tables 04h, 06h–08h. Temperature measurements below -40°C or above +102°C are clamped to 08h and C7h, respectively. The calculation of TINDEX is as follows: TINDEX = Temp _ Value + 40°C + 80h 2°C For the temperature-indexed LUTs, the index used during the lookup function for each table is as follows: Table 04h (MOD) 1 TINDEX6 TINDEX5 TINDEX4 TINDEX3 TINDEX2 TINDEX1 TINDEX0 Table 06h (APC) 1 0 TINDEX6 TINDEX5 TINDEX4 TINDEX3 TINDEX2 TINDEX1 Table 07h (DAC1) 1 0 TINDEX6 TINDEX5 TINDEX4 TINDEX3 TINDEX2 TINDEX1 Table 08h (DAC2) 1 0 TINDEX6 TINDEX5 TINDEX4 TINDEX3 TINDEX2 TINDEX1 Table 02h, Register 82h–83h: MODULATION REGISTER FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and MOD EN = 0) or (PW1 and RWTBL246 and MOD EN = 0) MEMORY TYPE Volatile 82h 0 0 0 0 0 0 0 28 83h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The digital value used for MODULATION and recalled from Table 04h at the adjusted memory address found in TINDEX. This register is updated at the end of the temperature conversion. 56 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and DAC1 EN = 0) or (PW1 and RWTBL246 and DAC1 EN = 0) MEMORY TYPE Volatile DS1874 Table 02h, Register 84h–85h: DAC1 VALUE 84h 0 0 0 0 0 0 0 28 85h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The digital value used for DAC1 and recalled from Table 07h at the adjusted memory address found in TINDEX. This register is updated at the end of the temperature conversion. REFIN
DAC1 VALUE 512 VDAC1 = Table 02h, Register 86h–87h: DAC2 VALUE FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and DAC2 EN = 0) or (PW1 and RWTBL246 and DAC2 EN = 0) MEMORY TYPE Volatile 86h 0 0 0 0 0 0 0 28 87h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The digital value used for DAC2 and recalled from Table 08h at the adjusted memory address found in TINDEX. This register is updated at the end of the temperature conversion. VDAC2 = REFIN
DAC2 VALUE 512 ______________________________________________________________________________________ 57 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register 88h: SAMPLE RATE 88h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) SEE SEE SEE SEE SEE APC_SR2 APC_SR1 BIT 7 BITS 7:3 APC_SR0 BIT 0 SEE APC_SR[2:0]: 3-bit sample rate for comparison of APC control. Defines the sample rate for comparison of APC control. APC_SR[2:0] BITS 2:0 58 Sample Period (tREP) (ns) 000b 800 001b 1200 010b 1600 011b 2000 100b 2800 101b 3200 110b 4400 111b 6400 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface DS1874 Table 02h, Register 89h: CNFGA 89h FACTORY DEFAULT 80h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) LOSC RESERVED INV LOS ASEL MASK INVRSOUT RESERVED BIT 7 RESERVED BIT 0 BIT 7 LOSC: LOS Configuration. Defines the source for the LOSOUT pin (see Figure 13). 0 = LOS LO alarm is used as the source. 1 = (Default) LOS input pin is used as the source. BIT 6 RESERVED BIT 5 INV LOS: Inverts the buffered input pin LOS to output pin LOSOUT (see Figure 13). 0 = Noninverted LOS to LOSOUT pin. 1 = Inverted LOS to LOSOUT pin. BIT 4 ASEL: Address Select. 0 = Device address is A2h. 1 = Byte DEVICE ADDRESS in Table 02h, Register 8Ch is used as the device address. BIT 3 MASK: 0 = Alarm-enable row exists at Table 01h, Registers F8h–FFh. Table 05h, Registers F8h–FFh are empty. 1 = Alarm-enable row exists at Table 05h, Registers F8h–FFh. Table 01h, Registers F8h–FFh are empty. BIT 2 INVRSOUT: Allow for inversion of RSELOUT pin (see Figure 13). 0 = RSELOUT is not inverted. 1 = RSELOUT is inverted. BITS 1:0 RESERVED ______________________________________________________________________________________ 59 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register 8Ah: CNFGB 8Ah FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) IN1C INVOUT1 RESERVED RESERVED RESERVED ALATCH QTLATCH BIT 7 60 BIT 0 BIT 7 IN1C: IN1 Software Control Bit (see Figure 13). 0 = IN1 pin’s logic controls OUT1 pin. 1 = OUT1 is active (bit 6 defines the polarity). BIT 6 INVOUT1: Inverts the active state for OUT1 (see Figure 13). 0 = Noninverted. 1 = Inverted. BITS 5:3 WLATCH RESERVED BIT 2 ALATCH: ADC Alarm’s Comparison Latch. Lower Memory, Registers 70h–71h. 0 = ADC alarm flags reflect the status of the last comparison. 1 = ADC alarm flags remain set. BIT 1 QTLATCH: Quick Trip’s Comparison Latch. Lower Memory, Registers 72h–73h. 0 = QT alarm flags reflect the status of the last comparison. 1 = QT alarm flags remain set. BIT 0 WLATCH: ADC Warning’s Comparison Latch. Lower Memory, Registers 74h–75h. 0 = ADC warning flags reflect the status of the last comparison. 1 = ADC warning flags remain set. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface 8Bh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RESERVED RESERVED TXDM34 TXDFG TXDFLT TXDIO DS1874 Table 02h, Register 8Bh: CNFGC RSSI_FC BIT 7 BITS 7:6 RSSI_FF BIT 0 RESERVED BIT 5 TXDM34: Enables TXD to reset alarms and warnings associated to MON3 and MON4 during a TXD event. 0 = TXD event has no effect on the MON3 and MON4 alarms, warnings, and quick trips. 1 = MON3 and MON4 alarms, warnings, and quick trips are reset during a TXD event. BIT 4 TXDFG: See Figure 12. 0 = FETG, an internal signal, has no effect on TXDOUT. 1 = FETG is enabled and ORed with other possible signals to create TXDOUT. BIT 3 TXDFLT: See Figure 12. 0 = TXF pin has no effect on TXDOUT. 1 = TXF pin is enabled and ORed with other possible signals to create TXDOUT. BIT 2 TXDIO: See Figure 12. 0 = (Default) TXD input signal is enabled and ORed with other possible signals to create TXDOUT. 1 = TXD input signal has no effect on TXDOUT. BITS 1:0 RSSI_FC and RSSI_FF: RSSI Force Coarse and RSSI Force Fine. Control bits for RSSI mode of operation on the MON3 conversion. 00b = Normal RSSI mode of operation (default). 01b = The fine settings of scale and offset are used for MON3 conversions. 10b = The coarse settings of scale and offset are used for MON3 conversions. 11b = Normal RSSI mode of operation. Table 02h, Register 8Ch: DEVICE ADDRESS 8Ch FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 BIT 7 26 25 24 23 22 21 20 BIT 0 This value becomes the I2C slave address for the main memory when the ASEL (Table 02h, Register 89h) bit is set. If A0h is programmed to this register, the auxiliary memory is disabled. ______________________________________________________________________________________ 61 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register 8Dh: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) This register is reserved. Table 02h, Register 8Eh: RIGHT-SHIFT1 (RSHIFT1) 8Eh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RESERVED MON12 MON11 MON10 RESERVED MON22 MON21 BIT 7 MON20 BIT 0 Allows for right-shifting the final answer of MON1 and MON2 voltage measurements. This allows for scaling the measurements to the smallest full-scale voltage and then right-shifting the final result so the reading is weighted to the correct LSB. Table 02h, Register 8Fh: RIGHT-SHIFT0 (RSHIFT0) 8Fh FACTORY DEFAULT 30h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RESERVED MON32 MON31 MON30 RESERVED MON42 MON41 BIT 7 MON40 BIT 0 Allows for right-shifting the final answer of MON3 and MON4 voltage measurements. This allows for scaling the measurements to the smallest full-scale voltage and then right-shifting the final result so the reading is weighted to the correct LSB. The MON3 right-shifting is only available for the fine mode of operation. The coarse mode does not right-shift. 62 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) DS1874 Table 02h, Register 90h–91h: RESERVED These registers are reserved. Table 02h, Register 92h–93h: VCC SCALE Table 02h, Register 94h–95h: MON1 SCALE Table 02h, Register 96h–97h: MON2 SCALE Table 02h, Register 98h–99h: MON3 FINE SCALE Table 02h, Register 9Ah–9Bh: MON4 SCALE Table 02h, Register 9Ch–9Dh: MON3 COARSE SCALE 92h, 94h, 96h, 98h, 9Ah, 9Ch 93h, 95h, 97h, 99h, 9Bh, 9Dh FACTORY CALIBRATED N/A READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 215 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 BIT 7 BIT 0 Controls the scaling or gain of the FS voltage measurements. The factory-calibrated value produces an FS voltage of 6.5536V for VCC; 2.5V for MON1, MON2, MON4; and 0.3125V for MON3 fine. Table 02h, Register 9Eh–A1h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) These registers are reserved. ______________________________________________________________________________________ 63 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register A2h–A3h: VCC OFFSET Table 02h, Register A4h–A5h: MON1 OFFSET Table 02h, Register A6h–A7h: MON2 OFFSET Table 02h, Register A8h–A9h: MON3 FINE OFFSET Table 02h, Register AAh–ABh: MON4 OFFSET Table 02h, Register ACh–ADh: MON3 COARSE OFFSET A2h, A4h, A6h, A8h, AAh, ACh A3h, A5h, A7h, A9h, ABh, ADh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) S S 215 214 213 212 211 210 29 28 27 26 25 24 23 22 BIT 7 BIT 0 Allows for offset control of these voltage measurements if desired. This number is two’s complement. Table 02h, Register AEh–AFh: INTERNAL TEMP OFFSET FACTORY CALIBRATED READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) AEh S 28 27 26 25 24 23 22 AFh 21 20 2-1 2-2 2-3 2-4 2-5 2-6 BIT 7 BIT 0 Allows for offset control of temperature measurement if desired. The final result must be XORed with BB40h before writing to this register. Factory calibration contains the desired value for a reading in degrees Celsius. 64 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface FACTORY DEFAULT FFFF FFFFh READ ACCESS N/A WRITE ACCESS PW2 or (PW1 and WPW1) MEMORY TYPE Nonvolatile (SEE) DS1874 Table 02h, Register B0h–B3h: PW1 B0h 231 230 229 228 227 226 225 224 B1h 223 222 221 220 219 218 217 216 B2h 215 214 213 212 211 210 29 28 B3h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The PWE value is compared against the value written to this location to enable PW1 access. At power-on, the PWE value is set to all ones. Thus, writing these bytes to all ones grants PW1 access on power-on without writing the password entry. All reads of this register are 00h. Table 02h, Register B4h–B7h: PW2 FACTORY DEFAULT FFFF FFFFh READ ACCESS N/A WRITE ACCESS PW2 MEMORY TYPE Nonvolatile (SEE) B4h 231 230 229 228 227 226 225 224 B5h 223 222 221 220 219 218 217 216 B6h 215 214 213 212 211 210 29 28 B7h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The PWE value is compared against the value written to this location to enable PW2 access. At power-on, the PWE value is set to all ones. Thus, writing these bytes to all ones grants PW2 access on power-on without writing the password entry. All reads of this register are 00h. ______________________________________________________________________________________ 65 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register B8h: LOS RANGING B8h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RESERVED HLOS2 HLOS1 HLOS0 RESERVED LLOS2 LLOS21 BIT 7 LLOS0 BIT 0 This register controls the full-scale range of the quick-trip monitoring for the differential input’s of MON3. BIT 7 RESERVED (Default = 0) HLOS[2:0]: HLOS Full-Scale Ranging. 3-bit value to select the FS comparison voltage for high LOS found on MON3. Default is 000b and creates an FS of 1.25V. BITS 6:4 BIT 3 HLOS[2:0] % of 1.25V FS Voltage 000b 100.00 1.250 001b 80.02 1.0003 010b 66.69 0.8336 011b 50.10 0.6263 100b 40.05 0.5006 101b 33.38 0.4173 110b 26.62 0.3328 111b 25.04 0.3130 RESERVED (Default = 0) LLOS[2:0]: LLOS Full-Scale Ranging. 3-bit value to select the FS comparison voltage for low LOS found on MON3. Default is 000b and creates an FS of 1.25V. BITS 2:0 66 LLOS[2:0] % of 1.25V FS Voltage 000b 100.00 1.250 001b 80.02 1.0003 010b 66.69 0.8336 011b 50.10 0.6263 100b 40.05 0.5006 101b 33.38 0.4173 110b 26.62 0.3328 111b 25.04 0.3130 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface B9h FACTORY DEFAULT 00h READ ACCESS PW2 WRITE ACCESS PW2 MEMORY TYPE Nonvolatile (SEE) RESERVED BIAS2 BIAS1 DS1874 Table 02h, Register B9h: COMP RANGING BIAS0 RESERVED APC2 BIT 7 APC1 APC0 BIT 0 The upper nibble of this byte controls the full-scale range of the quick-trip monitoring for BIAS. The lower nibble of this byte controls the full-scale range for the quick-trip monitoring of the APC reference as well as the closed-loop monitoring of APC. BIT 7 RESERVED (Default = 0) BIAS[2:0]: BIAS Full-Scale Ranging. 3-bit value to select the FS comparison voltage for BIAS found on MON1. Default is 000b and creates an FS of 1.25V. BITS 6:4 BIT 3 BIAS[2:0] % of 1.25V FS Voltage 000b 100.00 1.250 001b 80.04 1.0005 010b 66.73 0.8341 011b 50.10 0.6263 100b 40.12 0.5015 101b 33.46 0.4183 110b 28.70 0.3588 111b 25.13 0.3141 RESERVED (Default = 0) APC[2:0]: APC Full-Scale Ranging. 3-bit value to select the FS comparison voltage for MON2 with the APC. Default is 000b and creates an FS of 2.5V. BITS 2:0 APC[2:0] % of 2.50V FS Voltage 000b 100.00 2.500 001b 80.04 2.0010 010b 66.73 1.6683 011b 50.10 1.2525 100b 40.12 1.0030 101b 33.46 0.8365 110b 28.70 0.7175 111b 25.13 0.6283 ______________________________________________________________________________________ 67 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register BAh: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) This register is reserved. Table 02h, Register BBh: ISTEP BBh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 28 27 26 25 24 23 22 BIT 7 21 BIT 0 The initial step value used at power-on or after a TXD pulse to control the BIAS register. At startup, this value plus 20 = 1 is continuously added to the BIAS register value until the APC feedback (MON2) is greater than its threshold. At that time, a binary search is used to complete the startup of the APC closed loop. If the resulting math operation is greater than IBIASMAX (Table 02h, Register EEh), the result is not loaded into the BIAS register, but the binary search is begun to complete the initial search for APC. During startup, the BIAS register steps causing a higher bias value than IBIASMAX do not create the BIAS MAX alarm. The BIAS MAX alarm detection is enabled at the end of the binary search. Table 02h, Register BCh: HTXP BCh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 Fast-comparison DAC threshold adjust for high TXP. This value is added to the APC DAC value recalled from Table 06h. If the sum is greater than 0xFF, 0xFF is used. Comparisons greater than VHTXP, compared against VMON2, create a TXP HI alarm. The same ranging applied to the APC DAC should be used here. Full Scale VHTXP =
(HTXP + APC DAC) 255 68 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface BDh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 DS1874 Table 02h, Register BDh: LTXP 21 BIT 7 20 BIT 0 Fast-comparison DAC threshold adjust for low TXP. This value is subtracted from the APC DAC value recalled from Table 06h. If the difference is less than 0x00, 0x00 is used. Comparisons less than VLTXP, compared against VMON2, create a TXP LO alarm. The same ranging applied to the APC DAC should be used here. Full Scale VLTXP =  ( APC DAC
LTXP ) 255 Table 02h, Register BEh: HLOS BEh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 Fast-comparison DAC threshold adjust for high LOS. The combination of HLOS and LLOS creates a hysteresis comparator. As RSSI falls below the LLOS threshold, the LOS LO alarm bit is set to 1. The LOS alarm remains set until the RSSI input is found above the HLOS threshold setting, which clears the LOS LO alarm bit and sets the LOS HI alarm bit. At power-on, both LOS LO and LOS HI alarm bits are 0 and the hysteresis comparator uses the LLOS threshold setting. Full Scale VHLOS =
HLOS 255 Table 02h, Register BFh: LLOS BFh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 BIT 7 22 21 20 BIT 0 Fast-comparison DAC threshold adjust for low LOS. See HLOS (Table 02h, Register BEh) for functional description. VLLOS = Full Scale
LLOS 255 ______________________________________________________________________________________ 69 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register C0h: PW_ENA C0h FACTORY DEFAULT 10h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RWTBL78 RWTBL1C RWTBL2 RWTBL1A RWTBL1B WLOWER WAUXA BIT 7 70 WAUXB BIT 0 BIT 7 RWTBL78: Tables 07h–08h 0 = (Default) Read and write access for PW2 only. 1 = Read and write access for both PW1 and PW2. BIT 6 RWTBL1C: Table 01h or 05h bytes F8h–FFh. Table address is dependent on MASK bit (Table 02h, Register 89h). 0 = (Default) Read and write access for PW2 only. 1 = Read and write access for both PW1 and PW2. BIT 5 RWTBL2: Tables 02h, except for PW1 value locations (Table 02h, Registers B0h–B3h). 0 = (Default) Read and write access for PW2 only. 1 = Read and write access for both PW1 and PW2. BIT 4 RWTBL1A: Read and Write Table 01h, Registers 80h–BFh 0 = Read and write access for PW2 only. 1 = (Default) Read and write access for both PW1 and PW2. BIT 3 RWTBL1B: Read and Write Table 01h, Registers C0h–F7h 0 = (Default) Read and write access for PW2 only. 1 = Read and write access for both PW1 and PW2. BIT 2 WLOWER: Write Lower Memory Bytes 00h–5Fh in main memory. All users can read this area. 0 = (Default) Write access for PW2 only. 1 = Write access for both PW1 and PW2. BIT 1 WAUXA: Write Auxiliary Memory, Registers 00h–7Fh. All users can read this area. 0 = (Default) Write access for PW2 only. 1 = Write access for both PW1 and PW2. BIT 0 WAUXB: Write Auxiliary Memory, Registers 80h–FFh. All users can read this area. 0 = (Default) Write access for PW2 only. 1 = Write access for both PW1 and PW2. ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface C1h FACTORY DEFAULT 03h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) RWTBL46 RTBL1C RTBL2 RTBL1A RTBL1B WPW1 DS1874 Table 02h, Register C1h: PW_ENB WAUXAU WAUXBU BIT 7 BIT 0 BIT 7 RWTBL46: Read and Write Tables 04h, 06h 0 = (Default) Read and write access for PW2 only. 1 = Read and write access for both PW1 and PW2. BIT 6 RTBL1C: Read Table 01h or Table 05h, Registers F8h–FFh. Table address is dependent on MASK bit (Table 02h, Register 89h). 0 = (Default) Read access for PW2 only. 1 = Read access for PW1 and PW2. BIT 5 RTBL2: Read Table 02h except for PW1 value locations (Table 02h, Registers B0h–B3h) 0 = (Default) Read access for PW2 only. 1 = Read access for PW1 and PW2. BIT 4 RTBL1A: Read Table 01h, Registers 80h–BFh 0 = (Default) Read access for PW2 only. 1 = Read access for PW1 and PW2. BIT 3 RTBL1B: Read Table 01h, Registers C0h–F7h 0 = (Default) Read access for PW2 only. 1 = Read access for PW1 and PW2. BIT 2 WPW1: Write Register PW1 (Table 02h, Registers B0h–B3h). For security purposes these registers are not readable. 0 = (Default) Write access for PW2 only. 1 = Write access for PW1 and PW2. BIT 1 WAUXAU: Write Auxiliary Memory, Registers 00h–7Fh. All users can read this area. 0 = Write access for PW2 only. 1 = (Default) Write access for user, PW1 and PW2. BIT 0 WAUXBU: Write Auxiliary Memory, Registers 80h–FFh 0 = Read and write access for PW2 only. 1 = (Default) Read and write access for user, PW1 and PW2. ______________________________________________________________________________________ 71 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register C2h: MODTI C2h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 The modulation temperature index defines the TempCo boundary for the MODULATION LUT. The MODTC bit (Table 02h, Register C6h) defines the polarity of the TempCo. MODTI = Temp _ Value + 40°C + 80h 2°C Table 02h, Register C3h: DAC1TI C3h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 DAC1 temperature index (DAC1TI) defines the TempCo boundary for the DAC1 LUT. The DAC1TC bit (Table 02h, Register C6h) defines the polarity of the TempCo. This value is compared with the adjusted memory address used during the LUT recall, not the value in the TINDEX register (Table 02h, Register 81h). DAC1TI = 72 Temp _ Value + 40°C + 80h 4°C ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface C4h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 BIT 7 DS1874 Table 02h, Register C4h: DAC2TI 21 20 BIT 0 DAC2 temperature index defines the TempCo boundary for the DAC2 LUT. The DAC2TC bit (Table 02h, Register C6h) defines the polarity of the TempCo. This value is compared with the adjusted memory address used during the LUT recall, not the value in the TINDEX register (Table 02h, Register 81h). DAC2TI = Temp _ Value + 40°C + 80h 4°C Table 02h, Register C5h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) This register is reserved. ______________________________________________________________________________________ 73 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register C6h: LUTTC C6h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) MODTC DAC1TC DAC2TC RESERVED RESERVED RESERVED RESERVED BIT 7 BIT 0 BIT 7 MODTC: Modulation TempCo 0 = Negative TempCo. For a TINDEX below the MODTI value, the 8-bit recalled value from the MODULATION LUT is stored in the upper 8 bits of the MODULATION register. For a TINDEX greater than or equal to MODTI, the recalled value is stored in the lower 8 bits of the MODULATION register. 1 = Positive TempCo. For a TINDEX (Table 02h, Register 81h) below the MODTI value (Table 02h, Register C2h), the 8-bit recalled value from the MODULATION LUT is stored in the lower 8 bits of the Modulation register. For a TINDEX greater than or equal to MODTI, the recalled value is stored in the upper 8 bits of the Modulation register. BIT 6 DAC1TC: DAC1 TempCo 0 = Negative TempCo. For a TINDEX below the DAC1TI value, the 8-bit recalled value from the DAC1 LUT is stored in the upper 8 bits of the DAC1 DAC’s register. For a TINDEX greater than or equal to DAC1TI, the recalled value is stored in the lower 8 bits of the DAC1 DAC’s register. 1 = Positive TempCo. For a TINDEX (Table 02h, Register 81h) below the DAC1TI value (Table 02h, Register C3h), the 8-bit recalled value from the DAC1 LUT is stored in the lower 8 bits of the DAC1 DAC’s register. For a TINDEX greater than or equal to DAC1TI, the recalled value is stored in the upper 8 bits of the DAC1 DAC’s register. BIT 5 DAC2TC: DAC2 TempCo 0 = Negative TempCo. For a TINDEX below the DAC2TI value, the 8-bit recalled value from the DAC2 LUT is stored in the upper 8 bits of the DAC2 DAC’s register. For a TINDEX greater than or equal to DAC2TI, the recalled value is stored in the lower 8 bits of the DAC2 DAC’s register. 1 = Positive TempCo. For a TINDEX (Table 02h, Register 81h) below the DAC2TI value (Table 02h, Register C4h), the 8-bit recalled value from the DAC2 LUT is stored in the lower 8 bits of the DAC2 DAC’s register. For a TINDEX greater than or equal to DAC2TI, the recalled value is stored in the upper 8 bits of the DAC2 DAC’s register. BITS 4:0 74 RESERVED RESERVED ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface C7h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 DS1874 Table 02h, Register C7h: TBLSELPON 22 21 BIT 7 20 BIT 0 Chooses the initial value for the table-select byte (Lower Memory, Register 7Fh) at power-on. Table 02h, Register C8h–C9h: MAN BIAS FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and BIAS EN = 0) or (PW1 and RWTBL246 and BIAS EN = 0) MEMORY TYPE Volatile C8h 0 0 0 0 0 0 0 28 C9h 27 26 25 24 23 22 21 20 BIT 7 BIT 0 When BIAS EN (Table 02h, Register 80h) is written to 0, writes to these bytes control the BIAS register, which then updates the MAX3798/MAX3799 SET_IBIAS register. Table 02h, Register CAh: MAN_CNTL CAh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and BIAS EN = 0) or (PW1 and RWTBL246 and BIAS EN = 0) MEMORY TYPE Volatile RESERVED BIT 7 RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED MAN_CLK BIT 0 When BIAS EN (Table 02h, Register 80h) is written to 0, MAN_CLK controls the updates of the MAN BIAS value to the BIAS register. This new value is sent through the 3-wire interface. The values of MAN BIAS must be written with a separate write command. Setting MAN_CLK to a 1 clocks the MAN BIAS value to the BIAS register, which then updates the MAX3798/MAX3799 SET_IBIAS register. 1) Write the MAN BIAS value with a write command. 2) Set the MAN_CLK bit to a 1 with a separate write command. 3) Clear the MAN_CLK bit to a 0 with a separate write command. ______________________________________________________________________________________ 75 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register CBh–CCh: BIAS REGISTER FACTORY DEFAULT 0000h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE Volatile CBh RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED 28 CCh 27 26 25 24 23 22 21 20 BIT 7 BIT 0 The digital value used for BIAS and resolved from the APC. This register is updated after each decision of the APC loop. Table 02h, Register CDh: APC DAC CDh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS (PW2 and APC EN = 0) or (PW1 and RWTBL246 and APC EN = 0) MEMORY TYPE Volatile 27 26 25 24 23 22 21 BIT 7 20 BIT 0 The digital value used for APC reference and recalled from Table 06h at the adjusted memory address found in TINDEX. This register is updated at the end of the temperature conversion. Table 02h, Register CEh: DEVICE ID CEh FACTORY DEFAULT 74h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE ROM 0 1 1 1 0 1 0 BIT 7 Hardwired connections to show the device ID. 76 ______________________________________________________________________________________ 0 BIT 0 SFP+ Controller with Digital LDD Interface FACTORY DEFAULT DEVICE VERSION READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE ROM CFh DS1874 Table 02h, Register CFh: DEVICE VER DEVICE VERSION BIT 7 BIT 0 Hardwired connections to show the device version. Table 02h, Register D0h–D7h: HBATH D0h-D7h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 BIT 7 24 23 22 21 20 BIT 0 High-Bias Alarm Threshold (HBATH) is a digital clamp used to ensure that the DAC setting for BIAS currents does not exceed a set value. The table below shows the range of temperature for each byte’s location. The table shows a rising temperature; for a falling temperature there is 1°C of hysteresis. D0h Less than or equal to -8°C D1h Greater than -8°C up to +8°C D2h Greater than +8°C up to +24°C D3h Greater than +24°C up to +40°C D4h Greater than +40°C up to +56°C D5h Greater than +56°C up to +72°C D6h Greater than +72°C up to +88°C D7h Greater than +88°C ______________________________________________________________________________________ 77 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register D8h–E7h: EMPTY FACTORY DEFAULT 00h READ ACCESS N/A WRITE ACCESS N/A MEMORY TYPE None These registers do not exist. Table 02h, Register E8h: RXCTRL1 E8h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register E9h: RXCTRL2 E9h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. 78 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface EAh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 DS1874 Table 02h, Register EAh: SETCML 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register EBh: SETLOS EBh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register ECh: TXCTRL ECh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 BIT 7 26 25 24 23 22 21 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. ______________________________________________________________________________________ 79 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register EDh: IMODMAX EDh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register EEh: IBIASMAX EEh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. In addition, this value defines the maximum DAC value allowed for the upper 8 bits of BIAS output during APC closed-loop operations. During the intial step and binary search, this value does not cause an alarm but still clamps the BIAS register value. After the startup seqence (or normal APC operations), if the APC loop tries to create a BIAS value greater than this setting, it is clamped and creates a MAX BIAS alarm. 80 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface EFh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 DS1874 Table 02h, Register EFh: SETPWCTRL 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register F0h: SETTXDE F0h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) 27 26 25 24 23 22 BIT 7 21 20 BIT 0 MAX3798/MAX3799 register. After either VCC exceeds POA (after a POR event), the MAX3798/MAX3799 TX_POR bit is set high (visible in 3W TXSTAT1, Bit 7) or on a rising edge of TXD, this value is written to the MAX3798/ MAX3799 through the 3-wire interface. Table 02h, Register F1h–F7h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (SEE) These registers are reserved. ______________________________________________________________________________________ 81 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register F8h: 3WCTRL F8h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Volatile RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED 3WRW BIT 7 BITS 7:2 3WDIS BIT 0 RESERVED BIT 1 3WRW: Initiates a 3-wire write or read operation. The write command uses the memory address found in the 3-wire ADDRESS register (Table 02h, Register F9h) and the data from the 3-wire WRITE register (Table 02h, Register FAh). This bit clears itself at the completion of the write operation. The read command uses the memory address found in the 3-wire ADDRESS register (Table 02h, Register F9h). The address determines whether a read or write operation is to be performed. This bit clears itself at the completion of the read operation. 0 = (Default) Reads back as 0 when the write or read operation is completed. 1 = Initiates a 3-wire write or read operation. BIT 0 3WDIS: Disables all automatic communication across the 3-wire interface. This includes all updates from the LUTs, APC loop, and status registers. The only 3-wire communication is with the manual mode of operation. 0 = (Default) Automatic communication is enabled. 1 = Disables automatic communication. Table 02h, Register F9h: ADDRESS F9h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Volatile 27 26 25 24 23 22 21 BIT 7 20 BIT 0 This byte is used during manual 3-wire communication. When a manual read or write is initiated, this register contains the address for the operation. 82 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface FAh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Volatile 27 26 25 24 23 22 DS1874 Table 02h, Register FAh: WRITE 21 BIT 7 20 BIT 0 This byte is used during manual 3-wire communication. When a manual write is initiated, this register contains the data for the operation. Table 02h, Register FBh: READ FBh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE Volatile 27 26 25 24 23 22 21 BIT 7 20 BIT 0 This byte is used during maunual 3-wire communication. When a manual read is initiated, the return data is stored in this register. Table 02h, Register FCh: TXSTAT1 FCh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE Volatile 27 BIT 7 26 25 24 23 22 21 20 BIT 0 MAX3798/MAX3799 register. This value is read from the MAX3798/MAX3799 with the 3-wire interface every tRR (see the MAX3798/MAX3799 electrical characteristics). ______________________________________________________________________________________ 83 DS1874 SFP+ Controller with Digital LDD Interface Table 02h, Register FDh: TXSTAT2 FDh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS N/A MEMORY TYPE Volatile 27 26 25 24 23 22 21 BIT 7 20 BIT 0 MAX3798/MAX3799 register. This value is read from the MAX3798/MAX3799 with the 3-wire interface every tRR (see the MAX3798/MAX3799 electrical characteristics). Table 02h, Register FEh–FFh: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Volatile These registers are reserved. Table 04h Register Description Table 04h, Register 80h–C7h: MODULATION LUT 80h–C7h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (EE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 The digital value for the modulation DAC output. The MODULATION LUT is a set of registers assigned to hold the temperature profile for the MODULATION REGISTER. The values in this table determine the set point for the modulation voltage. The temperature measurement is used to index the LUT (TINDEX, Table 02h, Register 81h) in 2°C increments from -40°C to +102°C, starting at 80h in Table 04h. Register 80h defines the -40°C to -38°C MOD output, Register 81h defines the -38°C to -36°C MOD output, and so on. Values recalled from this EEPROM memory table are written into the MODULATION REGISTER (Table 02h, Register 82h–83h) location that holds the value until the next temperature conversion. The DS1874 can be placed into a manual mode (MOD EN bit, Table 02h, Register 80h), where the MODULATION REGISTER is directly controlled for calibration. If the temperature compensation functionality is not required, then program the entire Table 04h to the desired modulation setting. 84 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Table 06h, Register 80h–A3h: APC LUT 80h–A3h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (EE) 27 26 25 24 23 22 BIT 7 21 20 BIT 0 The APC LUT is a set of registers assigned to hold the temperature profile for the APC reference DAC. The values in this table combined with the APC bits in the COMP RANGING register (Table 02h, Register B9h) determine the set point for the APC loop. The temperature measurement is used to index the LUT (TINDEX, Table 02h, Register 81h) in 4°C increments from -40°C to +100°C, starting at Register 80h in Table 06h. Register 80h defines the -40°C to -36°C APC reference value, Register 81h defines the -36°C to -32°C APC reference value, and so on. Values recalled from this EEPROM memory table are written into the APC DAC (Table 02h, Register CDh) location that holds the value until the next temperature conversion. The DS1874 can be placed into a manual mode (APC EN bit, Table 02h, Register 80h), where the APC DAC can be directly controlled for calibration. If TE temperature compensation is not required by the application, program the entire LUT to the desired APC set point. Table 06h, Register A4h–A7h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246) WRITE ACCESS PW2 or (PW1 and RWTBL246) MEMORY TYPE Nonvolatile (EE) These registers are reserved. ______________________________________________________________________________________ 85 DS1874 Table 06h Register Descriptions DS1874 SFP+ Controller with Digital LDD Interface Table 07h Register Descriptions Table 07h, Register 80h–A3h: DAC1 LUT 80h–A3h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL78) and (PW1 and RTBL78) WRITE ACCESS PW2 or (PW1 and RWTBL78) MEMORY TYPE Nonvolatile (EE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 The DAC1 LUT is a set of registers assigned to hold the PWM profile for DAC1. The values in this table determine the set point for DAC1. The temperature measurement is used to index the LUT (TINDEX, Table 02h, Register 81h) in 4°C increments from -40°C to +100°C, starting at Register 80h in Table 07h. Register 80h defines the -40°C to -36°C DAC1 value, Register 81h defines -36°C to -32°C DAC1 value, and so on. Values recalled from this EEPROM memory table are written into the DAC1 VALUE (Table 02h, Registers 84h–85h) location, which holds the value until the next temperature conversion. The part can be placed into a manual mode (DAC1 EN bit, Table 02h, Register 80h), where DAC1 can be directly controlled for calibration. If temperature compensation is not required by the application, program the entire LUT to the desired DAC1 set point. Table 07h, Register A4h–A7h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL78) or (PW1 and RTBL78) WRITE ACCESS PW2 or (PW1 and RWTBL78) MEMORY TYPE Nonvolatile (EE) These registers are reserved. 86 ______________________________________________________________________________________ SFP+ Controller with Digital LDD Interface Table 08h, Register 80h–A3h: DAC2 LUT 80h–A3h FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL78) or (PW1 and RTBL78) WRITE ACCESS PW2 or (PW1 and RWTBL78) MEMORY TYPE Nonvolatile (EE) 27 26 25 24 23 22 21 BIT 7 20 BIT 0 The DAC2 LUT is set of registers assigned to hold the PWM profile for DAC2. The values in this table determine the set point for DAC2. The temperature measurement is used to index the LUT (TINDEX, Table 02h, Register 81h) in 4°C increments from -40°C to +100°C, starting at Register 80h in Table 08h. Register 80h defines the -40°C to -36°C DAC2 value, Register 81h defines -36°C to -32°C DAC2 value, and so on. Values recalled from this EEPROM memory table are written into the DAC2 VALUE (Table 02h, Registers 86h–87h) location that holds the value until the next temperature conversion. The DS1874 can be placed into a manual mode (DAC2 EN bit, Table 02h, Register 80h), where DAC2 can be directly controlled for calibration. If temperature compensation is not required by the application, program the entire LUT to the desired DAC2 set point. Table 08h, Register A4h–A7h: RESERVED FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and RWTBL78) or (PW1 and RTBL78) WRITE ACCESS PW2 or (PW1 and RWTBL78) MEMORY TYPE Nonvolatile (EE) These registers are reserved. Auxiliary Memory A0h Register Descriptions Auxiliary Memory A0h, Register 00h–FFh: EEPROM 00h–FFh FACTORY DEFAULT 00h READ ACCESS PW2 or (PW1 and WAUXA) or (PW1 and WAUXAU) WRITE ACCESS PW2 or (PW1 and WAUXA) MEMORY TYPE Nonvolatile (EE) 27 26 25 BIT 7 24 23 22 21 20 BIT 0 Accessible with the slave address A0h. ______________________________________________________________________________________ 87 DS1874 Table 08h Register Descriptions DS1874 SFP+ Controller with Digital LDD Interface Applications Information Power-Supply Decoupling To achieve best results, it is recommended that the power supply is decoupled with a 0.01µF or a 0.1µF capacitor. Use high-quality, ceramic, surface-mount capacitors, and mount the capacitors as close as possible to the VCC and GND pins to minimize lead inductance. SDA and SCL Pullup Resistors SDA is an open-collector output on the DS1874 that requires a pullup resistor to realize high logic levels. A master using either an open-collector output with a pullup resistor or a push-pull output driver can be utilized for SCL. Pullup resistor values should be chosen to ensure that the rise and fall times listed in the I2C AC Electrical Characteristics table are within specification. Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 28 TQFN-EP T2855+6 21-0140 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 88 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.