AD9628BCPZ-105

12-Bit, 125/105 MSPS, 1.8 V Dual Analog-to-Digital Converter AD9628 FEATURES FUNCTIONAL BLOCK DIAGRAM 1.8 V analog supply operation 1.8 V CMOS or LVDS outputs SNR = 71.2 dBFS @ 70 MHz SFDR = 93 dBc @ 70 MHz Low power: 101 mW/channel @ 125 MSPS Differential analog input with 650 MHz bandwidth IF sampling frequencies to 200 MHz On-chip voltage reference and sample-and-hold circuit 2 V p-p differential analog input DNL = ±0.25 LSB Serial port control options Offset binary, Gray code, or twos complement data format Optional clock duty cycle stabilizer Integer 1-to-8 input clock divider Data output multiplex option Built-in selectable digital test pattern generation Energy-saving power-down modes Data clock out with programmable clock and data alignment AVDD PROGRAMMING DATA VIN+A VREF SENSE VCM AD9628 REF SELECT MUX OPTION ADC VIN–A VIN–B ADC CLK+ CLK– Communications Diversity radio systems Multimode digital receivers GSM, EDGE, W-CDMA, LTE, CDMA2000, WiMAX, TD-SCDMA I/Q demodulation systems Smart antenna systems Broadband data applications Battery-powered instruments Hand-held scope meters Portable medical imaging Ultrasound Radar/LIDAR ORA D11A D0A DCOA DRVDD CMOS/LVDS OUTPUT BUFFER RBIAS VIN+B CMOS/LVDS OUTPUT BUFFER SPI DIVIDE 1 TO 8 DUTY CYCLE STABILIZER MODE CONTROLS SYNC DCS PDWN DFS OEB NOTES 1. PIN NAMES ARE FOR THE CMOS PIN CONFIGURATION ONLY; SEE FIGURE 7 FOR LVDS PIN NAMES. APPLICATIONS ORB D11B D0B DCOB Figure 1. PRODUCT HIGHLIGHTS 1. 2. 3. 4. Rev. C SDIO SCLK CSB AGND 09976-001 Data Sheet The AD9628 operates from a single 1.8 V analog power supply and features a separate digital output driver supply to accommodate 1.8 V CMOS or LVDS logic families. The patented sample-and-hold circuit maintains excellent performance for input frequencies up to 200 MHz and is designed for low cost, low power, and ease of use. A standard serial port interface supports various product features and functions, such as data output formatting, internal clock divider, power-down, DCO/data timing and offset adjustments. The AD9628 is packaged in a 64-lead RoHS-compliant LFCSP that is pin compatible with the AD9650/AD9269/ AD9268 16-bit ADC, the AD9258/AD9251/AD9648 14-bit ADCs, the AD9231 12-bit ADC, and the AD9608/AD9204 10-bit ADCs, enabling a simple migration path between 10-bit and 16-bit converters sampling from 20 MSPS to 125 MSPS. Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2011–2015 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com AD9628 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Voltage Reference ....................................................................... 27 Applications ....................................................................................... 1 Clock Input Considerations ...................................................... 28 Functional Block Diagram .............................................................. 1 Channel/Chip Synchronization ................................................ 30 Product Highlights ........................................................................... 1 Power Dissipation and Standby Mode .................................... 30 Revision History ............................................................................... 2 Digital Outputs ........................................................................... 31 General Description ......................................................................... 3 Timing.......................................................................................... 31 Specifications..................................................................................... 4 Output Test ...................................................................................... 32 DC Specifications ........................................................................... 4 Output Test Modes ..................................................................... 32 AC Specifications ........................................................................... 5 Serial Port Interface (SPI) .............................................................. 33 Digital Specifications ................................................................... 6 Configuration Using the SPI ..................................................... 33 Switching Specifications ................................................................ 8 Hardware Interface ..................................................................... 34 Timing Specifications .................................................................. 9 Configuration Without the SPI ................................................ 34 Absolute Maximum Ratings .......................................................... 12 SPI Accessible Features .............................................................. 34 Thermal Characteristics ............................................................ 12 Memory Map .................................................................................. 35 ESD Caution ................................................................................ 12 Reading the Memory Map Register Table............................... 35 Pin Configurations and Function Descriptions ......................... 13 Memory Map Register Table ..................................................... 36 Typical Performance Characteristics ........................................... 19 Memory Map Register Descriptions ........................................ 39 AD9628-125 ................................................................................ 19 Applications Information .............................................................. 41 AD9628-105 ................................................................................ 22 Design Guidelines ...................................................................... 41 Equivalent Circuits ......................................................................... 24 Outline Dimensions ....................................................................... 42 Theory of Operation ...................................................................... 25 Ordering Guide .......................................................................... 42 ADC Architecture ...................................................................... 25 Analog Input Considerations.................................................... 25 REVISION HISTORY 11/15—Rev. B to Rev. C Changed AD9516 to AD9516-0/AD9516-1/AD9516-2/ AD9516-3/AD9516-4/AD9516-5, and AD9517 to AD9517-0/ AD9517-1/AD9517-2/AD9517-3/AD9517-4 ............ Throughout Change to Figure 3 ......................................................................... 10 8/15—Rev. A to Rev. B Changes to Features Section and Product Highlights Section ... 1 Changes to General Description Section ...................................... 3 Changes to Aperture Uncertainty (Jitter, tJ) Parameter, Table 4 ................................................................................................ 8 Changes to Table 6 .......................................................................... 12 Changes to Table 7 .......................................................................... 12 Changes to RBIAS Pin Description and OEB Pin Description, Table 8 .............................................................................................. 13 Changes to RBIAS Pin Description and OEB Pin Description, Table 9 .............................................................................................. 15 Changes to RBIAS Pin Description and OEB Pin Description, Table 10 ............................................................................................ 17 Changes to Figure 35 ...................................................................... 24 Changes to Differential Input Configurations Section ............. 26 Deleted Figure 48; Renumbered Sequentially ............................ 27 Change to Clock Input Options Section ..................................... 28 Changed Built-In Self-Test (BIST) and Output Test Mode Section to Output Test Section ..................................................... 32 Deleted Built-In Self-Test (BIST) Section ................................... 32 Change to Configuration Without the SPI Section ................... 34 Changes to Channel-Specific Registers Section ......................... 35 Changes to Table 18 ....................................................................... 37 Changes to Bit 7—OEB Pin Enable Section................................ 40 Added Clock Stability Considerations Section........................... 41 Updated Outline Dimensions ....................................................... 42 11/14—Rev. 0 to Rev. A Changes to Table 10 ....................................................................... 18 Change to Figure 61 Caption ........................................................ 30 Updated Outline Dimensions ....................................................... 42 7/11—Revision 0: Initial Version Rev. C | Page 2 of 42 Data Sheet AD9628 GENERAL DESCRIPTION The AD9628 is a monolithic, dual-channel, 1.8 V supply, 12-bit, 125 MSPS/105 MSPS analog-to-digital converter (ADC). It features a high performance sample-and-hold circuit and onchip voltage reference. A differential clock input controls all internal conversion cycles. An optional duty cycle stabilizer (DCS) compensates for wide variations in the clock duty cycle while maintaining excellent overall ADC performance. The product uses multistage differential pipeline architecture with output error correction logic to provide 12-bit accuracy at 125 MSPS data rates and to guarantee no missing codes over the full operating temperature range. The digital output data is presented in offset binary, Gray code, or twos complement format. A data output clock (DCO) is provided for each ADC channel to ensure proper latch timing with receiving logic. 1.8 V CMOS or LVDS output logic levels are supported. Output data can also be multiplexed onto a single output bus. The ADC contains several features designed to maximize flexibility and minimize system cost, such as programmable clock and data alignment and programmable digital test pattern generation. The available digital test patterns include built-in deterministic and pseudorandom patterns, along with custom user-defined test patterns entered via the serial port interface (SPI). The AD9628 is available in a 64-lead RoHS-compliant LFCSP and is specified over the industrial temperature range (−40°C to +85°C). Rev. C | Page 3 of 42 AD9628 Data Sheet SPECIFICATIONS DC SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, DCS enabled, unless otherwise noted. Table 1. Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Gain Error Differential Nonlinearity (DNL) 1 Integral Nonlinearity (INL)1 MATCHING CHARACTERISTIC Offset Error Gain Error TEMPERATURE DRIFT Offset Error Gain Error INTERNAL VOLTAGE REFERENCE Output Voltage (1 V Mode) Load Regulation Error at 1.0 mA INPUT REFERRED NOISE VREF = 1.0 V ANALOG INPUT Input Span, VREF = 1.0 V Input Capacitance 2 Input Resistance (Differential) Input Common-Mode Voltage Input Common-Mode Range POWER SUPPLIES Supply Voltage AVDD DRVDD Supply Current IAVDD1 IDRVDD (1.8 V CMOS)1 IDRVDD (1.8 V LVDS)1 Temp Full Full Full Full Full 25°C Full 25°C Min 12 −1.0 AD9628-105 Typ Max Guaranteed −0.3 0.2 −1.0 ±0.25 AD9628-125 Typ Max Guaranteed −0.3 0.2 ±0.75 ±0.3 ±0.01 ±1.0 Full Full ±2 ±50 0.98 1.00 2 +0.4 ±5.0 ±0.6 ±0.25 ±0.75 Full Full Full Full +0.4 ±5.0 ±0.6 Min 12 ±0.3 ±0.6 ±4.0 ±0.01 ±1.0 ±0.6 ±4.0 ±2 ±50 1.02 0.98 1.00 2 Unit Bits % FSR % FSR LSB LSB LSB LSB % FSR % FSR ppm/°C ppm/°C 1.02 V mV 25°C 0.25 0.25 LSB rms Full Full Full Full Full 2 5 7.5 0.9 2 5 7.5 0.9 0.5 1.3 V p-p pF kΩ V V Full Full 1.7 1.7 1.8 1.8 1.9 1.9 V V 91.8 20.0 57.5 98 mA mA mA Full Full Full 1.3 0.5 1.8 1.8 1.9 1.9 1.7 1.7 79.0 17.0 56.0 84 Rev. C | Page 4 of 42 Data Sheet Parameter POWER CONSUMPTION DC Input Sine Wave Input (DRVDD = 1.8 V CMOS Output Mode)1 Sine Wave Input (DRVDD = 1.8 V LVDS Output Mode)1 Standby Power 3 Power-Down Power 1 2 3 AD9628 Temp Min AD9628-105 Typ Max Min AD9628-125 Typ Max Unit 148 201 mW mW Full Full 129 173 Full 243 269 mW Full Full 108 2.0 120 2.0 mW mW 182 212 Measured with a low input frequency, full-scale sine wave, with approximately 5 pF loading on each output bit. Input capacitance refers to the effective capacitance between one differential input pin and AGND. Standby power is measured with a dc input and with the CLK± pins active (1.8 V CMOS mode). AC SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, DCS enabled, unless otherwise noted. Table 2. Parameter 1 SIGNAL-TO-NOISE-RATIO (SNR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz SIGNAL-TO-NOISE AND DISTORTION (SINAD) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz WORST SECOND OR THIRD HARMONIC fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz Temp 25°C 25°C 25°C Full 25°C 25°C 25°C 25°C 25°C Full 25°C 25°C Min AD9628-105 Typ Max Min 71.6 71.6 71.3 AD9628-125 Typ Max 71.5 71.4 71.2 70.6 dBFS dBFS dBFS dBFS dBFS dBFS 70.2 71.0 69.4 70.9 69.6 71.5 71.5 71.2 71.4 71.3 71.1 Unit 69.9 68.1 69.8 68.3 dBFS dBFS dBFS dBFS dBFS dBFS 25°C 25°C 25°C 25°C 25°C 11.6 11.6 11.6 11.5 11.0 11.6 11.6 11.5 11.3 11.1 Bits Bits Bits Bits Bits 25°C 25°C 25°C Full 25°C 25°C −92 −90 −90 −92 −90 −93 dBc dBc dBc dBc dBc dBc 70.5 70 −82 −89 −83 Rev. C | Page 5 of 42 −85 −90 −84 AD9628 Parameter 1 SPURIOUS-FREE DYNAMIC RANGE (SFDR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz WORST OTHER (HARMONIC OR SPUR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 100 MHz fIN = 200 MHz TWO-TONE SFDR fIN = 29 MHz (−7 dBFS ), 32 MHz (−7 dBFS ) CROSSTALK 2 ANALOG INPUT BANDWIDTH 1 2 Data Sheet Temp 25°C 25°C 25°C Full 25°C 25°C Min AD9628-105 Typ Max Min 92 90 90 AD9628-125 Typ Max 92 90 93 82 dBc dBc dBc dBc dBc dBc 85 89 83 90 84 −96 −95 −95 −94 −94 −95 Unit 25°C 25°C 25°C Full 25°C 25°C −93 −92 −92 −91 dBc dBc dBc dBc dBc dBc 25°C Full 25°C 85 −95 650 85 −95 650 dBc dB MHz −87 −87 See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions. Crosstalk is measured at 100 MHz with −1.0 dBFS on one channel and no input on the alternate channel. DIGITAL SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, and DCS enabled, unless otherwise noted. Table 3. Parameter DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−) Logic Compliance Internal Common-Mode Bias Differential Input Voltage Input Voltage Range Input Common-Mode Range High Level Input Current Low Level Input Current Input Capacitance Input Resistance LOGIC INPUT (CSB) 1 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUT (SCLK/DFS/SYNC) 2 High Level Input Voltage Low Level Input Voltage High Level Input Current (VIN = 1.8 V) Low Level Input Current Input Resistance Input Capacitance AD9628-105/AD9628-125 Typ Max Temp Min Full Full Full Full Full Full Full Full CMOS/LVDS/LVPECL 0.9 0.3 3.6 AGND − 0.3 AVDD + 0.2 0.9 1.4 −10 +10 −10 +10 4 8 10 12 Full Full Full Full Full Full 1.22 0 −10 40 Full Full Full Full Full Full 1.22 0 −92 −10 Rev. C | Page 6 of 42 V V p-p V V µA µA pF kΩ DRVDD + 0.2 0.6 +10 132 V V µA µA kΩ pF DRVDD + 0.2 0.6 −135 +10 V V µA µA kΩ pF 26 2 26 2 Unit Data Sheet Parameter LOGIC INPUT/OUTPUT (SDIO/DCS)1 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUTS (OEB, PDWN)2 High Level Input Voltage Low Level Input Voltage High Level Input Current (VIN = 1.8 V) Low Level Input Current Input Resistance Input Capacitance DIGITAL OUTPUTS CMOS Mode—DRVDD = 1.8 V High Level Output Voltage IOH = 50 µA IOH = 0.5 mA Low Level Output Voltage IOL = 1.6 mA IOL = 50 µA LVDS Mode—DRVDD = 1.8 V Differential Output Voltage (VOD), ANSI Mode Output Offset Voltage (VOS), ANSI Mode Differential Output Voltage (VOD), Reduced Swing Mode Output Offset Voltage (VOS), Reduced Swing Mode 1 2 AD9628 Temp Min Full Full Full Full Full Full 1.22 0 −10 38 Full Full Full Full Full Full 1.22 0 −90 −10 Full Full 1.79 1.75 AD9628-105/AD9628-125 Typ Max Pull up. Pull down. Rev. C | Page 7 of 42 DRVDD + 0.2 0.6 +10 128 V V µA µA kΩ pF DRVDD + 0.2 0.6 −134 +10 V V µA µA kΩ pF 26 5 26 5 V V Full Full Full Full Full Full 290 1.15 160 1.15 Unit 345 1.25 200 1.25 0.2 0.05 V V 400 1.35 230 1.35 mV V mV V AD9628 Data Sheet SWITCHING SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, and DCS enabled, unless otherwise noted. Table 4. Parameter CLOCK INPUT PARAMETERS Input Clock Rate Conversion Rate 1 DCS Enabled DCS Disabled CLK Period—Divide-by-1 Mode (tCLK) CLK Pulse Width High (tCH) Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) DATA OUTPUT PARAMETERS CMOS Mode (DRVDD = 1.8 V) Data Propagation Delay (tPD) DCO Propagation Delay (tDCO) 2 DCO to Data Skew (tSKEW) LVDS Mode (DRVDD = 1.8 V) Data Propagation Delay (tPD) DCO Propagation Delay (tDCO)2 DCO to Data Skew (tSKEW) CMOS Mode Pipeline Delay (Latency) LVDS Mode Pipeline Delay (Latency) Channel A/Channel B Wake-Up Time (Power Down) 3 Wake-Up Time (Standby) Out-of-Range Recovery Time Temp Min AD9628-105 Typ Max Full AD9628-125 Typ Max Unit 1000 MHz 125 125 MSPS MSPS ns ns ns ps rms 4.4 4.4 +1.0 ns ns ns 1000 Full Full Full Full Full Full 20 10 Full Full Full 1.8 2.0 −1.2 Full Full Full Full Full Full Full Full Min 105 105 20 10 9.52 4.76 1.0 0.137 −0.20 2.9 3.1 −0.1 2 Rev. C | Page 8 of 42 4.4 4.4 +1.0 1.8 2.0 −1.2 2.9 3.1 −0.1 2.4 2.4 2.4 2.4 +0.03 16 16/16.5 350 250 2 Conversion rate is the clock rate after the divider. Additional DCO delay can be added by writing to Bit 0 through Bit 2 in SPI Register 0x17 (see Table 18). 3 Wake-up time is defined as the time required to return to normal operation from power-down mode. 1 8 4 1.0 0.137 +0.25 −0.20 +0.03 16 16/16.5 350 250 2 +0.25 ns ns ns Cycles Cycles µs ns Cycles Data Sheet AD9628 TIMING SPECIFICATIONS Table 5. Parameter SYNC TIMING REQUIREMENTS tSSYNC tHSYNC SPI TIMING REQUIREMENTS tDS tDH tCLK tS tH tHIGH tLOW tEN_SDIO tDIS_SDIO Description Limit Unit SYNC to rising edge of CLK+ setup time SYNC to rising edge of CLK+ hold time 0.24 0.40 ns typ ns typ Setup time between the data and the rising edge of SCLK Hold time between the data and the rising edge of SCLK Period of the SCLK Setup time between CSB and SCLK Hold time between CSB and SCLK SCLK pulse width high SCLK pulse width low Time required for the SDIO pin to switch from an input to an output relative to the SCLK falling edge Time required for the SDIO pin to switch from an output to an input relative to the SCLK rising edge 2 2 40 2 2 10 10 10 ns min ns min ns min ns min ns min ns min ns min ns min 10 ns min Timing Diagrams N–1 N+4 tA N VIN N+1 tCH N+5 N+3 N+2 tCLK CLK+ CLK– tDCO DCOA/DCOB CH A/CH B DATA N – 17 N – 16 N – 15 N – 14 tPD Figure 2. CMOS Default Output Mode Data Output Timing Rev. C | Page 9 of 42 N – 13 N – 12 09976-002 tSKEW AD9628 Data Sheet N–1 N+4 tA N VIN N+1 tCH N+5 N+3 N+2 tCLK CLK+ CLK– tDCO DCOA/DCOB tSKEW CH A DATA tPD CH B CH A CH B CH A CH B CH A CH B CH A CH B N – 16 N – 16 N – 15 N – 15 N – 14 N – 14 N – 13 N – 13 N – 12 CH B DATA 09976-003 CH A CH B CH A CH B CH A CH B CH A CH B CH A N – 16 N – 16 N – 15 N – 15 N – 14 N – 14 N – 13 N – 13 N – 12 Figure 3. CMOS Interleaved Output Mode Data Output Timing N–1 N+4 tA N VIN N+1 tCH tDCO DCO+ D0+ (LSB) PARALLEL INTERLEAVED MODE D0– (LSB) D11+ (MSB) D11– (MSB) CHANNEL MULTIPLEXED MODE CHANNEL A CHANNEL MULTIPLEXED MODE CHANNEL B D1+/D0+ (LSB) D1–/D0– (LSB) D11+/D10+ (MSB) D11–/D10– (MSB) D1+/D0+ (LSB) D1–/D0– (LSB) D11+/D10+ (MSB) D11–/D10– (MSB) tPD tSKEW CH A N – 16 CH B N – 16 CH A N – 15 CH B N – 15 CH A N – 14 CH B N – 14 CH A N – 13 CH B N – 13 CH A N – 12 CH A N – 16 CH B N – 16 CH A N – 15 CH B N – 15 CH A N – 14 CH B N – 14 CH A N – 13 CH B N – 13 CH A N – 12 CH A0 N – 16 CH A1 N – 16 CH A0 N – 15 CH A1 N – 15 CH A0 N – 14 CH A1 N – 14 CH A0 N – 13 CH A1 N – 13 CH A0 N – 12 CH A10 N – 16 CH A11 N – 16 CH A10 N – 15 CH A11 N – 15 CH A10 N – 14 CH A11 N – 14 CH A10 N – 13 CH A11 N – 13 CH A10 N – 12 CH B0 N – 16 CH B1 N – 16 CH B0 N – 15 CH B1 N – 15 CH B0 N – 14 CH B1 N – 14 CH B0 N – 13 CH B1 N – 13 CH B0 N – 12 CH B10 N – 16 CH B11 N – 16 CH B10 N – 15 CH B11 N – 15 CH B10 N – 14 CH B11 N – 14 CH B10 N – 13 CH B11 N – 13 CH B10 N – 12 Figure 4. LVDS Modes for Data Output Timing Rev. C | Page 10 of 42 09976-004 DCO– N+2 tCLK CLK+ CLK– N+5 N+3 Data Sheet AD9628 CLK+ tHSYNC 09976-005 tSSYNC SYNC Figure 5. SYNC Input Timing Requirements Rev. C | Page 11 of 42 AD9628 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS Table 6. Parameter Electrical AVDD to AGND DRVDD to AGND VIN+A/VIN+B, VIN−A/VIN−B to AGND CLK+, CLK− to AGND SYNC to DRVDD VCM to AGND RBIAS to AGND CSB to AGND SCLK/DFS to AGND SDIO/DCS to AGND OEB PDWN D0A/D0B through D11A/D11B to AGND DCOA/DCOB to AGND Environmental Operating Temperature Range (Ambient) Maximum Junction Temperature Under Bias Storage Temperature Range (Ambient) Rating −0.3 V to +2.0 V −0.3 V to +2.0 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −40°C to +85°C 150°C −65°C to +150°C The exposed paddle must be soldered to the ground plane for the LFCSP package. Soldering the exposed paddle to the printed circuit board (PCB) increases the reliability of the solder joints and maximizes the thermal capability of the package. Table 7. Thermal Resistance Package Type 64-Lead LFCSP 9 mm × 9 mm (CP-64-4) Airflow Velocity (m/sec) 0 1.0 2.5 θJA1, 2 22.3 19.5 17.5 θJC1, 3 1.4 N/A5 N/A5 θJB1, 4 11.8 N/A5 N/A5 JT1, 2 0.1 0.2 0.2 Unit °C/W °C/W °C/W 1 Per JEDEC 51-7, plus JEDEC 25-5 2S2P test board. Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air). Per MIL-Std 883, Method 1012.1. 4 Per JEDEC JESD51-8 (still air). 5 N/A means not applicable. 2 3 Typical θJA is specified for a 4-layer PCB with a solid ground plane. As shown Table 7, airflow improves heat dissipation, which reduces θJA. In addition, metal in direct contact with the package leads from metal traces, through holes, ground, and power planes reduces θJA. ESD CAUTION Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. Rev. C | Page 12 of 42 Data Sheet AD9628 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD AVDD VIN+B VIN–B AVDD AVDD RBIAS VCM SENSE VREF AVDD AVDD VIN–A VIN+A AVDD AVDD PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PIN 1 INDICATOR AD9628 PARALLEL CMOS TOP VIEW (Not to Scale) 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 PDWN OEB CSB SCLK/DFS SDIO/DCS ORA D11A (MSB) D10A D9A D8A D7A DRVDD D6A D5A D4A D3A NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION. 09976-006 D8B D9B DRVDD D10B D11B (MSB) ORB DCOB DCOA NC NC NC DRVDD NC D0A (LSB) D1A D2A 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 CLK+ CLK– SYNC NC NC NC NC D0B (LSB) D1B DRVDD D2B D3B D4B D5B D6B D7B Figure 6. Parallel CMOS Pin Configuration (Top View) Table 8. Pin Function Descriptions (Parallel CMOS Mode) Pin No. Mnemonic ADC Power Supplies 10, 19, 28, 37 DRVDD AVDD 49, 50, 53, 54, 59, 60, 63, 64 NC 4, 5, 6, 7, 25, 26, 27, 29 0 AGND, Exposed Pad ADC Analog 51 52 62 61 55 56 58 57 1 2 Digital Input 3 Type Description Supply Supply Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). No Connect. Do not connect to these pins. Ground The exposed thermal pad on the bottom of the package provides the analog ground for the part. This exposed pad must be connected to ground for proper operation. VIN+A VIN−A VIN+B VIN−B VREF SENSE RBIAS VCM CLK+ CLK− Input Input Input Input Input/Output Input Input/Output Output Input Input Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (−) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (−) for Channel B. Voltage Reference Input/Output. Reference Mode Selection. External Reference Bias Resistor. Connect to 10 kΩ (1% tolerance) resistor to ground. Common-Mode Level Bias Output for Analog Inputs. ADC Clock Input—True. ADC Clock Input—Complement. SYNC Input Digital Synchronization Pin. Slave mode only. Rev. C | Page 13 of 42 AD9628 Pin No. Mnemonic Digital Outputs 30 D0A (LSB) 31 D1A 32 D2A 33 D3A 34 D4A 35 D5A 36 D6A 38 D7A 39 D8A 40 D9A 41 D10A 42 D11A (MSB) 43 ORA 8 D0B (LSB) 9 D1B 11 D2B 12 D3B 13 D4B 14 D5B 15 D6B 16 D7B 17 D8B 18 D9B 20 D10B 21 D11B (MSB) 22 ORB 24 DCOA 23 DCOB SPI Control 45 SCLK/DFS 44 SDIO/DCS 46 CSB ADC Configuration 47 OEB 48 PDWN Data Sheet Type Description Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A CMOS Output Data. Channel A Overrange Output. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B CMOS Output Data. Channel B Overrange Output Channel A Data Clock Output. Channel B Data Clock Output. Input Input/Output Input SPI Serial Clock/Data Format Select Pin in External Pin Mode. SPI Serial Data I/O/Duty Cycle Stabilizer Pin in External Pin Mode. SPI Chip Select (Active Low). Input Input Output Enable Input (Active Low). Power-Down Input in External Pin Mode. In SPI mode, this input can be configured as power-down or standby. Rev. C | Page 14 of 42 AD9628 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD AVDD VIN+B VIN–B AVDD AVDD RBIAS VCM SENSE VREF AVDD AVDD VIN–A VIN+A AVDD AVDD Data Sheet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PIN 1 INDICATOR AD9628 INTERLEAVED PARALLEL LVDS TOP VIEW (Not to Scale) 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 PDWN OEB CSB SCLK/DFS SDIO/DCS OR+ OR– D11+ (MSB) D11– (MSB) D10+ D10– DRVDD D9+ D9– D8+ D8– NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION. 09976-007 D2– D2+ DRVDD D3– D3+ D4– D4+ DCO– DCO+ D5– D5+ DRVDD D6– D6+ D7– D7+ 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 CLK+ CLK– SYNC NC NC NC NC NC NC DRVDD NC NC D0– (LSB) D0+ (LSB) D1– D1+ Figure 7. LFCSP Interleaved Parallel LVDS Pin Configuration (Top View) Table 9. Pin Function Descriptions (Interleaved Parallel LVDS Mode) Pin No. Mnemonic ADC Power Supplies 10, 19, 28, 37 DRVDD AVDD 49, 50, 53, 54, 59, 60, 63, 64 NC 4, 5, 6, 7, 8, 9, 11, 12 0 AGND, Exposed Pad ADC Analog 51 VIN+A 52 VIN−A 62 VIN+B 61 VIN−B 55 VREF 56 SENSE 58 RBIAS 57 VCM 1 CLK+ 2 CLK− Digital Input 3 SYNC Type Description Supply Supply Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). No Connect. Do not connect to these pins. Ground The exposed thermal pad on the bottom of the package provides the analog ground for the part. This exposed pad must be connected to ground for proper operation. Input Input Input Input Input/Output Input Input/Output Output Input Input Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (−) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (−) for Channel B. Voltage Reference Input/Output. Reference Mode Selection. External Reference Bias Resistor. Connect to 10 kΩ (1% tolerance) resistor to ground. Common-Mode Level Bias Output for Analog Inputs. ADC Clock Input—True. ADC Clock Input—Complement. Input Digital Synchronization Pin. Slave mode only. Rev. C | Page 15 of 42 AD9628 Pin No. Mnemonic Digital Outputs 14 D0+ (LSB) 13 D0− (LSB) 16 D1+ 15 D1− 18 D2+ 17 D2− 21 D3+ 20 D3− 23 D4+ 22 D4− 27 D5+ 26 D5− 30 D6+ 29 D6− 32 D7+ 31 D7− 34 D8+ 33 D8− 36 D9+ 35 D9− 39 D10+ 38 D10− 41 D11+ (MSB) 40 D11− (MSB) 43 OR+ 42 OR− 25 DCO+ 24 DCO− SPI Control 45 SCLK/DFS 44 SDIO/DCS 46 CSB ADC Configuration 47 OEB 48 PDWN Data Sheet Type Description Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Channel A/Channel B LVDS Output Data 0—True. Channel A/Channel B LVDS Output Data 0—Complement. Channel A/Channel B LVDS Output Data 1—True. Channel A/Channel B LVDS Output Data 1—Complement. Channel A/Channel B LVDS Output Data 2 —True. Channel A/Channel B LVDS Output Data 2—Complement. Channel A/Channel B LVDS Output Data 3—True. Channel A/Channel B LVDS Output Data 3—Complement. Channel A/Channel B LVDS Output Data 4—True. Channel A/Channel B LVDS Output Data 4—Complement. Channel A/Channel B LVDS Output Data 5—True. Channel A/Channel B LVDS Output Data 5—Complement. Channel A/Channel B LVDS Output Data 6—True. Channel A/Channel B LVDS Output Data 6—Complement. Channel A/Channel B LVDS Output Data 7—True. Channel A/Channel B LVDS Output Data 7—Complement. Channel A/Channel B LVDS Output Data 8—True. Channel A/Channel B LVDS Output Data 8—Complement. Channel A/Channel B LVDS Output Data 9—True. Channel A/Channel B LVDS Output Data 9—Complement. Channel A/Channel B LVDS Output Data 10—True. Channel A/Channel B LVDS Output Data 10—Complement. Channel A/Channel B LVDS Output Data 11—True. Channel A/Channel B LVDS Output Data 11—Complement. Channel A/Channel B LVDS Overrange Output—True. Channel A/Channel B LVDS Overrange Output—Complement. Channel A/Channel B LVDS Data Clock Output—True. Channel A/Channel B LVDS Data Clock Output—Complement. Input Input/Output Input SPI Serial Clock/Data Format Select Pin in External Pin Mode. SPI Serial Data I/O/Duty Cycle Stabilizer Pin in External Pin Mode. SPI Chip Select (Active Low). Input Input Output Enable Input (Active Low). Power-Down Input in External Pin Mode. In SPI mode, this input can be configured as power-down or standby. Rev. C | Page 16 of 42 AD9628 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD AVDD VIN+B VIN–B AVDD AVDD RBIAS VCM SENSE VREF AVDD AVDD VIN–A VIN+A AVDD AVDD Data Sheet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PIN 1 INDICATOR AD9628 CHANNEL MULTIPLEXED LVDS TOP VIEW (Not to Scale) 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 PDWN OEB CSB SCLK/DFS SDIO/DCS OR+ OR– A D11+/D10+ (MSB) A D11–/D10– (MSB) A D9+/D8+ A D9–/D8– DRVDD A D7+/D6+ A D7–/D6– A D5+/D4+ A D5–/D4– NOTES 1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION. 09976-008 B D7–/D6– B D7+/D6+ DRVDD B D9–/D8– B D9+/D8+ B D11–/D10– (MSB) B D11+/D10+ (MSB) DCO– DCO+ NC NC DRVDD A D1–/D0– (LSB) A D1+/D0+ (LSB) A D3–/D2– A D3+/D2+ 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 CLK+ CLK– SYNC NC NC NC NC NC NC DRVDD B D1–/D0– (LSB) B D1+/D0+ (LSB) B D3–/D2– B D3+/D2+ B D5–/D4– B D5+/D4+ Figure 8. LFCSP Channel Multiplexed LVDS Pin Configuration (Top View) Table 10. Pin Function Descriptions (Channel Multiplexed Parallel LVDS Mode) Pin No. Mnemonic ADC Power Supplies 10, 19, 28, 37 DRVDD AVDD 49, 50, 53, 54, 59, 60, 63, 64 NC 4, 5, 6, 7, 8, 9, 26, 27 0 AGND, Exposed Pad Type Description Supply Supply Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). Do Not Connect. Ground The exposed thermal pad on the bottom of the package provides the analog ground for the part. This exposed pad must be connected to ground for proper operation. Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (−) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (−) for Channel B. Voltage Reference Input/Output. Reference Mode Selection. External Reference Bias Resistor. Connect to 10 kΩ (1% tolerance) resistor to ground. Common-Mode Level Bias Output for Analog Inputs. ADC Clock Input—True. ADC Clock Input—Complement. Digital Synchronization Pin. Slave mode only. ADC Analog 51 52 62 61 55 56 58 VIN+A VIN−A VIN+B VIN−B VREF SENSE RBIAS Input Input Input Input Input/Output Input Input/Output 57 1 2 3 VCM CLK+ CLK− SYNC Output Input Input Input Rev. C | Page 17 of 42 AD9628 Pin No. Mnemonic Digital Outputs 11 B D1−/D0− (LSB) 12 B D1+/D0+ (LSB) 13 B D3−/D2− 14 B D3+/D2+ 15 B D5−/D4− 16 B D5+/D4+ 17 B D7−/D6− 18 B D7+/D6+ 20 B D9−/D8− 21 B D9+/D8+ 22 B D11−/D10− (MSB) 23 B D11+/D10+ (MSB) 29 A D1−/D0− (LSB) 30 A D1+/D0+ (LSB) 32 A D3+/D2+ 31 A D3−/D2− 34 A D5+/D4+ 33 A D5−/D4− 36 A D7+/D6+ 35 A D7−/D6− 39 A D9+/D8+ 38 A D9−/D8− 41 A D11+/D10+ (MSB) 40 A D11−/D10− (MSB) 43 OR+ 42 OR− 25 DCO+ 24 DCO− SPI Control 45 SCLK/DFS 44 SDIO/DCS 46 CSB ADC Configuration 47 OEB 48 PDWN Data Sheet Type Description Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Channel B LVDS Output Data 1/Data 0—Complement. Channel B LVDS Output Data 1/Data 0—True. Channel B LVDS Output Data 3/Data 2—Complement. Channel B LVDS Output Data 3/Data 2—True. Channel B LVDS Output Data 5/Data 4—Complement. Channel B LVDS Output Data 5/Data 4—True. Channel B LVDS Output Data 7/Data 6—Complement. Channel B LVDS Output Data 7/Data 6—True. Channel B LVDS Output Data 9/Data 8—Complement. Channel B LVDS Output Data 9/Data 8—True. Channel B LVDS Output Data 11/Data 10—Complement. Channel B LVDS Output Data 11/Data 10—True. Channel A LVDS Output Data 1/Data 0—Complement. Channel A LVDS Output Data 1/Data 0—True. Channel A LVDS Output Data 3/Data 2—True. Channel A LVDS Output Data 3/Data 2—Complement. Channel A LVDS Output Data 5/Data 4—True. Channel A LVDS Output Data 5/Data 4—Complement. Channel A LVDS Output Data 7/Data 6—True. Channel A LVDS Output Data 7/Data 6—Complement. Channel A LVDS Output Data 9/Data 8—True. Channel A LVDS Output Data 9/Data 8—Complement. Channel A LVDS Output Data 11/Data 10—True. Channel A LVDS Output Data 11/Data 10—Complement. Channel A/Channel B LVDS Overrange Output—True. Channel A/Channel B LVDS Overrange Output—Complement. Channel A/Channel B LVDS Data Clock Output—True. Channel A/Channel B LVDS Data Clock Output—Complement. Input Input/Output Input SPI Serial Clock/Data Format Select Pin in External Pin Mode. SPI Serial Data I/O/Duty Cycle Stabilizer Pin in External Pin Mode. SPI Chip Select (Active Low). Input Input Output Enable Input (Active Low). Power-Down Input in External Pin Mode. In SPI mode, this input can be configured as power-down or standby. Rev. C | Page 18 of 42 Data Sheet AD9628 TYPICAL PERFORMANCE CHARACTERISTICS AD9628-125 AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, and DCS enabled, unless otherwise noted. 0 –40 –60 –80 –100 –40 –60 –80 10 20 30 40 50 60 FREQUENCY (MHz) –120 0 AMPLITUDE (dBFS) AMPLITUDE (dBFS) –80 –100 60 60 –40 –60 –80 0 10 20 30 40 50 60 09976-023 –100 FREQUENCY (MHz) Figure 10. Single-Tone FFT with fIN = 30.5 MHz 125MSPS 70.1MHz @-1dBFS SNR = 70.4dB (71.4dBFS) –20 SFDR = 93.0dBc –40 –60 –80 10 20 30 40 50 FREQUENCY (MHz) 60 09976-024 –100 0 –120 0 10 20 30 40 50 FREQUENCY (MHz) Figure 13. Single-Tone FFT with fIN = 200.5 MHz 0 AMPLITUDE (dBFS) 50 125MSPS 200.5MHz AT –1dBFS SNR = 68.8dB (69.8dBFS) –20 SFDR = 85.0dBc –60 –120 40 0 –40 –120 30 Figure 12. Single-Tone FFT with fIN = 100.5 MHz 125MSPS 30.5MHz AT –1dBFS SNR = 70.6dB (71.6dBFS) SFDR = 84.5dBc –20 20 FREQUENCY (MHz) Figure 9. Single-Tone FFT with fIN = 9.7 MHz 0 10 09976-025 0 09976-026 –100 09976-022 –120 125MSPS 100.5MHz @-1dBFS SNR = 70.1dB (71.1dBFS) SFDR = 91.6dBc –20 AMPLITUDE (dBFS) –20 AMPLITUDE (dBFS) 0 125MSPS 9.7MHz AT –1dBFS SNR = 70.7dB (71.7dBFS) SFDR = 92.3dBc Figure 11. Single-Tone FFT with fIN = 70.1 MHz Rev. C | Page 19 of 42 AD9628 Data Sheet 0 0 –15 –20 SFDR/IMD3 (dBFS/dBc) –45 –60 –75 2F1 – F2 2F2 – F1 2F1 + F2 + –105 –60 –80 SFDR (dBFS) –100 –120 18 36 24 42 30 FREQUENCY (MHz) 48 54 60 09976-125 12 6 Figure 14. Two-Tone FFT with fIN1 = 29 MHz and fIN2 = 32 MHz 95 90 80 SNR/SFDR (dBc/dBFS) SFDR AT 25°C 80 75 SNRFS AT 25°C 70 65 250 SFDR 30 SNR –60 –50 –40 –30 –20 –10 0 INPUT AMPLITUDE (dBFS) Figure 18. SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz Figure 15. SNR/SFDR vs. Input Frequency (AIN) with 2 V p-p Full Scale 120 120 SNR/SFDR (dBFS/dBc) SFDR (dBc) 100 SNR (dBFS) 80 60 40 20 100 SFDR (dBc) 80 SNR (dBFS) 60 40 20 5 15 25 35 45 55 65 75 85 SAMPLE RATE (MSPS) 95 105 115 125 09976-020 0 SNRFS 0 –70 09976-108 200 ANALOG INPUT FREQUENCY (MHz) SNR/SFDR (dBFS/dBc) 40 10 150 SFDRFS 50 55 100 –10 60 20 50 –20 –30 70 60 0 –40 Figure 17. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 29 MHz and fIN2 = 32 MHz 100 85 –50 –60 INPUT AMPLITUDE (dBFS) 100 90 SNR/SFDR (dBFS/dBc) –120 –70 09976-122 IMD3 (DBFS) –135 50 IMD3 (dBc) 09976-111 –90 SFDR (dBc) –40 Figure 16. SNR/SFDR vs. Sample Rate with AIN = 9.7 MHz 0 5 15 25 35 45 55 65 75 85 SAMPLE RATE (MSPS) 95 105 115 125 Figure 19. SNR/SFDR vs. Sample Rate with AIN = 70 MHz Rev. C | Page 20 of 42 09976-021 AMPLITUDE (Hz) –30 AD9628 1.0 1.0 0.5 0.5 INL ERROR (LSB) 0 –0.5 0 500 1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE 09976-019 –0.5 –1.0 Figure 20. DNL Error with fIN = 9.7 MHz 700 600 500 400 300 200 100 N–1 N N+1 OUTPUT CODE N+2 09976-109 NUMBER OF HITS (Thousands) 800 N–2 –1.0 0 500 1000 1500 2000 2500 3000 OUTPUT CODE Figure 22. INL Error with fIN = 9.7 MHz 900 0 0 Figure 21. Shorted Input Histogram Rev. C | Page 21 of 42 3500 4000 09976-018 DNL ERROR (LSB) Data Sheet AD9628 Data Sheet AD9628-105 AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, and DCS enabled, unless otherwise noted. 0 –40 –60 –80 –100 –40 –60 –80 0 10 20 30 40 50 FREQUENCY (MHz) –120 0 0 105MSPS 30.5MHz AT –1dBFS SNR = 70.7dB (71.7dBFS) –20 SFDR = 90.6dBc 40 50 105MSPS 200.5MHz AT –1dBFS SNR = 68.7dB (69.7dBFS) SFDR = 81dBc –20 –40 AMPLITUDE (dBFS) –60 –80 –100 –40 –60 –80 10 20 30 40 50 FREQUENCY (MHz) –120 09976-014 0 20 30 40 50 Figure 27. Single-Tone FFT with fIN = 200.5 MHz 100 105MSPS 70.1MHz AT –1dBFS SNR = 70.3dB (71.3dBFS) SFDR = 95dBc 95 90 SNR/SFDR (dBFS/dBc) –20 10 FREQUENCY (MHz) Figure 24. Single-Tone FFT with fIN = 30.5 MHz 0 0 09976-017 –100 –40 –60 –80 SFDR AT 25°C 85 80 75 SNRFS AT 25°C 70 65 60 –100 55 0 10 20 30 40 FREQUENCY (MHz) Figure 25. Single-Tone FFT with fIN = 70.1 MHz 50 50 09976-015 –120 0 50 100 150 200 ANALOG INPUT FREQUENCY (MHz) 250 09976-104 AMPLITUDE (dBFS) 30 Figure 26. Single-Tone FFT with fIN = 100.5 MHz 0 AMPLITUDE (dBFS) 20 FREQUENCY (MHz) Figure 23. Single-Tone FFT with fIN = 9.7 MHz –120 10 09976-016 –100 09976-013 –120 105MSPS 100.5MHz AT –1dBFS SNR = 70.2dB (71.2dBFS) SFDR = 90.6dBc –20 AMPLITUDE (dBFS) –20 AMPLITUDE (dBFS) 0 105MSPS 9.7MHz AT –1dBFS SNR = 70.8dB (71.8dBFS) SFDR = 94dBc Figure 28. SNR/SFDR vs. Input Frequency (AIN) with 2 V p-p Full Scale Rev. C | Page 22 of 42 Data Sheet AD9628 120 120 SFDR (dBc) 80 100 SNR/SFDR (dBFS/dBc) SNR (dBFS) 60 40 20 80 SNR (dBFS) 60 40 20 5 15 25 35 45 55 65 75 85 95 105 SAMPLE RATE (MSPS) 0 09976-011 0 SFDR (dBc) 5 15 25 35 45 55 65 75 85 95 105 SAMPLE RATE (MSPS) Figure 29. SNR/SFDR vs. Sample Rate with AIN = 9.7 MHz 09976-012 SNR/SFDR (dBFS/dBc) 100 Figure 32. SNR/SFDR vs. Sample Rate with AIN = 70.1 MHz 1.0 2.0 1.5 1.0 INL ERROR (LSB) DNL ERROR (LSB) 0.5 0 –0.5 0.5 0 –0.5 –1.0 500 0 1000 1500 2000 2500 3000 3500 4000 OUTPUT CODE Figure 30. DNL Error with fIN = 9.7 MHz SNRFS 60 40 SFDR 0 –90 –80 SNR –70 –60 –50 –40 –30 –20 –10 0 INPUT AMPLITUDE (dBFS) 09976-100 SNR/SFDR (dBc/dBFS) 100 SFDRFS 20 0 500 1000 1500 2000 2500 3000 OUTPUT CODE Figure 33. INL Error with fIN = 9.7 MHz 120 80 –2.0 Figure 31. SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz Rev. C | Page 23 of 42 3500 4000 09976-009 –1.0 09976-010 –1.5 AD9628 Data Sheet EQUIVALENT CIRCUITS DRVDD AVDD 350Ω SCLK/DFS, SYNC, OEB, AND PDWN 30kΩ 09976-045 09976-039 VIN±x Figure 34. Equivalent Analog Input Circuit Figure 38. Equivalent SCLK/DFS, SYNC, OEB, and PDWN Input Circuit AVDD 5Ω CLK+ 15kΩ 375Ω SENSE 09976-043 0.9V 15kΩ 5Ω 09976-040 CLK– Figure 39. Equivalent SENSE Circuit Figure 35. Equivalent Clock Input Circuit DRVDD DRVDD AVDD PAD 30kΩ 09976-044 09976-047 CSB 350Ω Figure 36. Equivalent Digital Output Circuit Figure 40. Equivalent CSB Input Circuit AVDD DRVDD AVDD 30kΩ 350Ω 30kΩ 375Ω VREF 09976-042 7.5kΩ Figure 37. Equivalent SDIO/DCS Input Circuit Figure 41. Equivalent VREF Circuit Rev. C | Page 24 of 42 09976-048 SDIO/DCS Data Sheet AD9628 THEORY OF OPERATION ANALOG INPUT CONSIDERATIONS The analog input to the AD9628 is a differential switchedcapacitor circuit designed for processing differential input signals. This circuit can support a wide common-mode range while maintaining excellent performance. By using an input common-mode voltage of midsupply, users can minimize signal-dependent errors and achieve optimum performance. In nondiversity applications, the AD9628 can be used as a baseband or direct downconversion receiver, where one ADC is used for I input data and the other is used for Q input data. H CPAR H VIN+x CSAMPLE Synchronization capability is provided to allow synchronized timing between multiple channels or multiple devices. S S Programming and control of the AD9628 is accomplished using a 3-bit, SPI-compatible serial interface. VIN–x The AD9628 architecture consists of a multistage, pipelined ADC. Each stage provides sufficient overlap to correct for flash errors in the preceding stage. The quantized outputs from each stage are combined into a final 12-bit result in the digital correction logic. The pipelined architecture permits the first stage to operate with a new input sample while the remaining stages operate with preceding samples. Sampling occurs on the rising edge of the clock. Each stage of the pipeline, excluding the last, consists of a low resolution flash ADC connected to a switched-capacitor DAC and an interstage residue amplifier (for example, a multiplying digital-to-analog converter (MDAC)). The residue amplifier magnifies the difference between the reconstructed DAC output and the flash input for the next stage in the pipeline. One bit of redundancy is used in each stage to facilitate digital correction of flash errors. The last stage simply consists of a flash ADC. The output staging block aligns the data, corrects errors, and passes the data to the CMOS/LVDS output buffers. The output buffers are powered from a separate (DRVDD) supply, allowing digital output noise to be separated from the analog core. During power-down, the output buffers go into a high impedance state. CSAMPLE S H CPAR ADC ARCHITECTURE S H 09976-049 The AD9628 dual ADC design can be used for diversity reception of signals, where the ADCs are operating identically on the same carrier but from two separate antennae. The ADCs can also be operated with independent analog inputs. The user can sample any fS/2 frequency segment from dc to 200 MHz, using appropriate low-pass or band-pass filtering at the ADC inputs with little loss in ADC performance. Operation to 300 MHz analog input is permitted but occurs at the expense of increased ADC noise and distortion. Figure 42. Switched-Capacitor Input Circuit The clock signal alternately switches the input circuit between sample-and-hold mode (see Figure 42). When the input circuit is switched to sample mode, the signal source must be capable of charging the sample capacitors and settling within one-half of a clock cycle. A small resistor in series with each input can help reduce the peak transient current injected from the output stage of the driving source. In addition, low Q inductors or ferrite beads can be placed on each leg of the input to reduce high differential capacitance at the analog inputs and, therefore, achieve the maximum bandwidth of the ADC. Such use of low Q inductors or ferrite beads is required when driving the converter front end at high IF frequencies. Either a shunt capacitor or two single-ended capacitors can be placed on the inputs to provide a matching passive network. This ultimately creates a low-pass filter at the input to limit unwanted broadband noise. See the AN-742 Application Note, the AN-827 Application Note, and the Analog Dialogue article “Transformer-Coupled Front-End for Wideband A/D Converters” (Volume 39, April 2005) for more information. In general, the precise values depend on the application. Rev. C | Page 25 of 42 AD9628 Data Sheet Input Common Mode driver can be configured in a Sallen-Key filter topology to provide band limiting of the input signal. 200Ω VIN 33Ω VIN–x 90Ω ADA4938 0.1µF 120Ω ADC 10pF 33Ω VIN+x VCM Figure 44. Differential Input Configuration Using the ADA4938-2 For baseband applications below ~10 MHz where SNR is a key parameter, differential transformer-coupling is the recommended input configuration. An example is shown in Figure 45. To bias the analog input, the VCM voltage can be connected to the center tap of the secondary winding of the transformer. SFDR (DBC) 80 SNR (DBFS) VIN+x R 70 2V p-p 49.9Ω ADC C 60 R 50 40 VIN–x VCM 0.1µF 30 09976-051 100 Figure 45. Differential Transformer-Coupled Configuration 20 The signal characteristics must be considered when selecting a transformer. Most RF transformers saturate at frequencies below a few megahertz (MHz). Excessive signal power can also cause core saturation, which leads to distortion. 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 INPUT COMMON-MODE VOLTAGE (V) Figure 43. SNR/SFDR vs. Input Common-Mode Voltage, fIN = 70 MHz, fS = 125 MSPS At input frequencies in the second Nyquist zone and above, the noise performance of most amplifiers is not adequate to achieve the true SNR performance of the AD9628. For applications above ~10 MHz where SNR is a key parameter, differential double balun coupling is the recommended input configuration (see Figure 46). Differential Input Configurations Optimum performance is achieved while driving the AD9628 in a differential input configuration. For baseband applications, the AD8138, ADA4937-2, and ADA4938-2 differential drivers provide excellent performance and a flexible interface to the ADC. An alternative to using a transformer-coupled input at frequencies in the second Nyquist zone is to use the AD8352 differential driver. An example is shown in Figure 47. See the AD8352 data sheet for more information. The output common-mode voltage of the ADA4938-2 is easily set with the VCM pin of the AD9628 (see Figure 44), and the 0.1µF 0.1µF 2V p-p R VIN+x 25Ω PA S S P 0.1µF 25Ω ADC C 0.1µF R VCM VIN–x Figure 46. Differential Double Balun Input Configuration VCC 0.1µF ANALOG INPUT 0Ω 16 1 8, 13 11 2 CD RD RG 3 ANALOG INPUT 0.1µF 0Ω R VIN+x 200Ω C AD8352 10 4 5 0.1µF 0.1µF 0.1µF 200Ω R 14 0.1µF 0.1µF Figure 47. Differential Input Configuration Using the AD8352 Rev. C | Page 26 of 42 ADC VIN–x VCM 09976-054 0 0.5 09976-028 10 09976-053 SNR/SFDR (dBFS/dBc) AVDD 200Ω An on-board, common-mode voltage reference is included in the design and is available from the VCM pin. The VCM pin must be decoupled to ground by a 0.1 μF capacitor, as described in the Applications Information section. 90 76.8Ω 09976-050 The analog inputs of the AD9628 are not internally dc-biased. Therefore, in ac-coupled applications, the user must provide a dc bias externally. Setting the device so that VCM = AVDD/2 is recommended for optimum performance, but the device can function over a wider range with reasonable performance, as shown in Figure 43. Data Sheet AD9628 In any configuration, the value of Shunt Capacitor C is dependent on the input frequency and source impedance and may need to be reduced or removed. Table 11 displays the suggested values to set the RC network. However, these values are dependent on the input signal and should be used only as a starting guide. VIN+A/VIN+B VIN–A/VIN–B ADC CORE Table 11. Example RC Network Frequency Range (MHz) 0 to 70 70 to 200 R Series (Ω Each) 33 125 VREF C Differential (pF) 22 Open 1.0µF 0.1µF SELECT LOGIC SENSE It is not recommended to drive the AD9628 inputs single-ended. 0.5V A comparator within the AD9628 detects the potential at the SENSE pin and configures the reference into two possible modes, which are summarized in Table 12. If SENSE is grounded, the reference amplifier switch is connected to the internal resistor divider (see Figure 48), setting VREF to 1.0 V. Figure 48. Internal Reference Configuration If the internal reference of the AD9628 is used to drive multiple converters to improve gain matching, the loading of the reference by the other converters must be considered. Figure 49 shows how the internal reference voltage is affected by loading. 0 –0.5 –1.0 INTERNAL VREF = 1.00V –1.5 –2.0 –2.5 –3.0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 LOAD CURRENT (mA) Figure 49. VREF Accuracy vs. Load Current Table 12. Reference Configuration Summary Selected Mode Fixed Internal Reference Fixed External Reference SENSE Voltage (V) AGND to 0.2 AVDD Resulting VREF (V) 1.0 internal 1.0 applied to external VREF pin Rev. C | Page 27 of 42 Resulting Differential Span (V p-p) 2.0 2.0 2.0 09976-056 Internal Reference Connection ADC REFERENCE VOLTAGE ERROR (%) A stable and accurate 1.0 V voltage reference is built into the AD9628. The VREF can be configured using either the internal 1.0 V reference or an externally applied 1.0 V reference voltage. The various reference modes are summarized in the sections that follow. The Reference Decoupling section describes the best practices PCB layout of the reference. 09976-055 VOLTAGE REFERENCE AD9628 Data Sheet External Reference Operation Clock Input Options The use of an external reference may be necessary to enhance the gain accuracy of the ADC or improve thermal drift characteristics. Figure 50 shows the typical drift characteristics of the internal reference in 1.0 V mode. The AD9628 has a very flexible clock input structure. The clock input can be a CMOS, LVDS, LVPECL, or sine wave signal. Regardless of the type of signal being used, clock source jitter is of the most concern, as described in the Jitter Considerations section. 4 Figure 52 and Figure 53 show two preferred methods for clocking the AD9628 (at clock rates up to 1 GHz prior to internal CLK divider). A low jitter clock source is converted from a singleended signal to a differential signal using either an RF transformer or an RF balun. 3 VREF ERROR (mV) 1 0 The RF balun configuration is recommended for clock frequencies between 125 MHz and 1 GHz, and the RF transformer is recommended for clock frequencies from 10 MHz to 200 MHz. The antiparallel Schottky diodes across the transformer/balun secondary limit clock excursions into the AD9628 to approximately 0.8 V p-p differential. –2 –3 –4 –6 –40 –20 0 20 40 TEMPERATURE (°C) 60 09976-057 –5 80 Figure 50. Typical VREF Drift When the SENSE pin is tied to AVDD, the internal reference is disabled, allowing the use of an external reference. An internal reference buffer loads the external reference with an equivalent 7.5 kΩ load (see Figure 41). The internal buffer generates the positive and negative full-scale references for the ADC core. Therefore, the external reference must be limited to a maximum of 1.0 V. This limit helps prevent the large voltage swings of the clock from feeding through to other portions of the AD9628 while preserving the fast rise and fall times of the signal that are critical to a low jitter performance. Mini-Circuits® ADT1-1WT, 1:1 Z CLOCK INPUT 0.1µF CLK+ 100Ω ADC 0.1µF SCHOTTKY DIODES: HSMS2822 0.1µF Figure 52. Transformer-Coupled Differential Clock (Up to 200 MHz) For optimum performance, clock the AD9628 sample clock inputs, CLK+ and CLK−, with a differential signal. The signal is typically ac-coupled into the CLK+ and CLK− pins via a transformer or capacitors. These pins are biased internally (see Figure 51) and require no external bias. 1nF CLOCK INPUT AVDD 0.1µF CLK+ 50Ω ADC 0.1µF 1nF CLK– SCHOTTKY DIODES: HSMS2822 0.9V Figure 53. Balun-Coupled Differential Clock (Up to 1 GHz) CLK– 2pF 09976-058 2pF 50Ω XFMR CLK– CLOCK INPUT CONSIDERATIONS CLK+ 0.1µF 09976-059 –1 Figure 51. Equivalent Clock Input Circuit Rev. C | Page 28 of 42 09976-060 VREF ERROR (mV) 2 Data Sheet AD9628 Input Clock Divider If a low jitter clock source is not available, another option is to ac couple a differential PECL signal to the sample clock input pins, as shown in Figure 54. The AD9510/AD9511/AD9512/ AD9513/AD9514/AD9515/AD9516-0/AD9516-1/AD9516-2/ AD9516-3/AD9516-4/AD9516-5/AD9517-0/AD9517-1/ AD9517-2/AD9517-3/AD9517-4 clock drivers offer excellent jitter performance. 0.1µF CLOCK INPUT The AD9628 clock divider can be synchronized using the external SYNC input. Bit 1 and Bit 2 of Register 0x3A allow the clock divider to be resynchronized on every SYNC signal or only on the first SYNC signal after the register is written. A valid SYNC causes the clock divider to reset to its initial state. This synchronization feature allows multiple parts to have their clock dividers aligned to guarantee simultaneous input sampling. 0.1µF CLK+ 0.1µF 50kΩ AD951x PECL DRIVER 240Ω 50kΩ 100Ω 0.1µF ADC Clock Duty Cycle CLK– 09976-061 CLOCK INPUT The AD9628 contains an input clock divider with the ability to divide the input clock by integer values between 1 and 8. 240Ω Figure 54. Differential PECL Sample Clock (Up to 1 GHz) A third option is to ac couple a differential LVDS signal to the sample clock input pins, as shown in Figure 55. The AD9510/ AD9511/AD9512/AD9513/AD9514/AD9515/AD9516-0/ AD9516-1/AD9516-2/AD9516-3/AD9516-4/AD9516-5/ AD9517-0/AD9517-1/AD9517-2/AD9517-3/AD9517-4 clock drivers offer excellent jitter performance. 0.1µF CLOCK INPUT CLK+ 0.1µF 50kΩ 100Ω 0.1µF ADC CLK– 09976-062 CLOCK INPUT The AD9628 contains a duty cycle stabilizer (DCS) that retimes the nonsampling (falling) edge, providing an internal clock signal with a nominal 50% duty cycle. This allows the user to provide a wide range of clock input duty cycles without affecting the performance of the AD9628. Noise and distortion performance are nearly flat for a wide range of duty cycles with the DCS on, as shown in Figure 57. 0.1µF AD951x LVDS DRIVER 50kΩ Typical high speed ADCs use both clock edges to generate a variety of internal timing signals and, as a result, may be sensitive to clock duty cycle. Commonly, a ±5% tolerance is required on the clock duty cycle to maintain dynamic performance characteristics. Figure 55. Differential LVDS Sample Clock (Up to 1 GHz) In some applications, it may be acceptable to drive the sample clock inputs with a single-ended 1.8 V CMOS signal. In such applications, drive the CLK+ pin directly from a CMOS gate, and bypass the CLK− pin to ground with a 0.1 μF capacitor (see Figure 56). Jitter in the rising edge of the input is still of concern and is not easily reduced by the internal stabilization circuit. The duty cycle control loop does not function for clock rates less than 20 MHz, nominally. The loop has a time constant associated with it that must be considered in applications in which the clock rate can change dynamically. A wait time of 1.5 μs to 5 μs is required after a dynamic clock frequency increase or decrease before the DCS loop is relocked to the input signal. 75 DCS ON 70 VCC CLOCK INPUT 50Ω1 1kΩ AD951x CMOS DRIVER OPTIONAL 0.1µF 100Ω 1kΩ 65 CLK+ ADC 0.1µF 150Ω RESISTOR IS OPTIONAL. 09976-063 CLK– SNR (dBFS) 0.1µF 60 DCS OFF 55 50 Figure 56. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz) 40 35 40 45 50 55 POSITIVE DUTY CYCLE (%) Figure 57. SNR vs. DCS On/Off Rev. C | Page 29 of 42 60 65 09976-110 45 AD9628 Data Sheet Jitter Considerations primarily by the strength of the digital drivers and the load on each output bit. High speed, high resolution ADCs are sensitive to the quality of the clock input. The degradation in SNR from the low frequency SNR (SNRLF) at a given input frequency (fINPUT) due to jitter (tJRMS) can be calculated by SNRHF = −10 log[(2π × fINPUT × tJRMS)2 + 10 (  SNRLF /10 ) The maximum DRVDD current (IDRVDD) can be calculated as IDRVDD = VDRVDD × CLOAD × fCLK × N where N is the number of output bits (26, in the case of the AD9628). ] In the previous equation, the rms aperture jitter represents the clock input jitter specification. IF undersampling applications are particularly sensitive to jitter, as illustrated in Figure 58. This maximum current occurs when every output bit switches on every clock cycle, that is, a full-scale square wave at the Nyquist frequency of fCLK/2. In practice, the DRVDD current is established by the average number of output bits switching, which is determined by the sample rate and the characteristics of the analog input signal. 80 75 0.05ps Reducing the capacitive load presented to the output drivers can minimize digital power consumption. The data in Figure 59 was taken in CMOS mode using the same operating conditions as those used for the power supplies and power consumption specifications in Table 1 with a 5 pF load on each output driver. 70 SNR (dBFS) 0.2ps 65 0.5ps 60 100 240 90 100 1k FREQUENCY (MHz) Figure 58. SNR vs. Input Frequency and Jitter The clock input should be treated as an analog signal in cases where aperture jitter may affect the dynamic range of the AD9628. To avoid modulating the clock signal with digital noise, keep power supplies for clock drivers separate from the ADC output driver supplies. Low jitter, crystal-controlled oscillators make the best clock sources. If the clock is generated from another type of source (by gating, dividing, or another method), it should be retimed by the original clock at the last step. 60 50 30 90 20 IDRVDD 10 0 5 25 45 65 85 40 125 105 ENCODE RATE (MSPS) Figure 59. AD9628-125 Power and Current vs. Clock Rate (1.8 V CMOS Output Mode) 200 90 80 180 IAVDD The AD9628 has a SYNC input that offers the user flexible synchronization options for synchronizing sample clocks across multiple ADCs. The input clock divider can be enabled to synchronize on a single occurrence of the SYNC signal or on every occurrence. The SYNC input is internally synchronized to the sample clock; however, to ensure that there is no timing uncertainty between multiple parts, the SYNC input signal should be externally synchronized to the input clock signal, meeting the setup and hold times shown in Table 5. Drive the SYNC input using a single-ended CMOS-type signal. SUPPLY CURRENT (mA) 70 CHANNEL/CHIP SYNCHRONIZATION As shown in Figure 59, the analog core power dissipated by the AD9628 is proportional to its sample rate. The digital power dissipation of the CMOS outputs are determined 140 TOTAL POWER 40 See the AN-501 Application Note and the AN-756 Application Note for more information. POWER DISSIPATION AND STANDBY MODE 190 09976-105 10 IAVDD 70 160 60 140 50 TOTAL POWER 120 40 100 POWER (mW) 1 09976-064 3.0ps 45 2.0ps 2.5ps SUPPLY CURRENT (mA) 80 1.5ps 50 POWER (mW) 1.0ps 30 80 20 10 0 60 IDRVDD 5 25 45 65 85 105 40 ENCODE RATE (MSPS) Figure 60. AD9628-105 Power and Current vs. Clock Rate (1.8 V CMOS Output Mode) Rev. C | Page 30 of 42 09976-101 55 Data Sheet AD9628 The AD9628 is placed in power-down mode either by the SPI port or by asserting the PDWN pin high. In this state, the ADC typically dissipates less than 2 mW. During power-down, the output drivers are placed in a high impedance state. Asserting the PDWN pin low returns the AD9628 to its normal operating mode. Note that PDWN is referenced to the digital output driver supply (DRVDD) and should not exceed that supply voltage. As detailed in the AN-877 Application Note, Interfacing to High Speed ADCs via SPI, the data format can be selected for offset binary, twos complement, or Gray code when using the SPI control. Low power dissipation in power-down mode is achieved by shutting down the reference, reference buffer, biasing networks, and clock. Internal capacitors are discharged when entering powerdown mode and then must be recharged when returning to normal operation. As a result, wake-up time is related to the time spent in power-down mode, and shorter power-down cycles result in proportionally shorter wake-up times. Digital Output Enable Function (OEB) When using the SPI, the user can place the ADC in powerdown mode or standby mode. Standby mode allows the user to keep the internal reference circuitry powered when faster wakeup times are required. See the Memory Map section for more details. DIGITAL OUTPUTS The AD9628 output drivers can be configured to interface with either 1.8 V CMOS or 1.8 V LVDS logic families. The default output mode is CMOS, with each channel output on separate busses as shown in Figure 2. In CMOS output mode, the CMOS output drivers are sized to provide sufficient output current to drive a wide variety of logic families. However, large drive currents tend to cause current glitches on the supplies and may affect converter performance. Applications requiring the ADC to drive large capacitive loads or large fanouts may require external buffers or latches. The CMOS output can also be configured for interleaved CMOS output mode via the SPI port. In interleaved CMOS mode, the data for both channels is output onto a single output bus to reduce the total number of traces required. The timing diagram for interleaved CMOS output mode is shown in Figure 3. The interleaved CMOS output mode is enabled globally onto both output channels via Bit 5 in Register 0x14. The unused channel output can be disabled by selecting the appropriate bit (Bit 1 or Bit 0) in Register 0x05 and then writing a 1 to the local (channel-specific) output port disable bit (Bit 4) in Register 0x14. The output data format can be selected to be either offset binary or twos complement by setting the SCLK/DFS pin when operating in the external pin mode (see Table 13). Table 13. SCLK/DFS Mode Selection (External Pin Mode) Voltage at Pin AGND DRVDD SCLK/DFS Offset binary (default) Twos complement SDIO/DCS DCS disabled DCS enabled (default) The AD9628 has a flexible three-state ability for the digital output pins. The three-state mode is enabled through the SPI interface and can subsequently be controlled using the OEB pin or through the SPI. Once enabled via the SPI (Bit 7) in Register 0x101, and the OEB pin is low, the output data drivers and DCOs are enabled. If the OEB pin is high, the output data drivers and DCOs are placed in a high impedance state. This OEB function is not intended for rapid access to the data bus. Note that OEB is referenced to the digital output driver supply (DRVDD) and should not exceed that supply voltage. When using the SPI interface, the data outputs and DCO of each channel can be independently three-stated by using the output port disable bit (Bit 4) in Register 0x14. TIMING The AD9628 provides latched data with a pipeline delay of 16 clock cycles. Data outputs are available one propagation delay (tPD) after the rising edge of the clock signal. Minimize the length of the output data lines and loads placed on them to reduce transients within the AD9628. These transients can degrade converter dynamic performance. The lowest typical conversion rate of the AD9628 is 10 MSPS. At clock rates below 10 MSPS, dynamic performance can degrade. Data Clock Output (DCO) The AD9628 provides two data clock output (DCO) signals intended for capturing the data in an external register. In CMOS output mode, the data outputs are valid on the rising edge of DCO, unless the DCO clock polarity has been changed via the SPI. In LVDS output mode, the DCO and data output switching edges are closely aligned. Additional delay can be added to the DCO output using SPI Register 0x17 to increase the data setup time. In this case, the Channel A output data is valid on the rising edge of DCO, and the Channel B output data is valid on the falling edge of DCO. See Figure 2, Figure 3, and Figure 4 for a graphical timing description of the output modes. Table 14. Output Data Format Input (V) VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− Condition (V) < −VREF − 0.5 LSB = −VREF =0 = +VREF − 1.0 LSB > +VREF − 0.5 LSB Offset Binary Output Mode 0000 0000 0000 0000 0000 0000 1000 0000 0000 1111 1111 1111 1111 1111 1111 Rev. C | Page 31 of 42 Twos Complement Mode 1000 0000 0000 1000 0000 0000 0000 0000 0000 0111 1111 1111 0111 1111 1111 OR 1 0 0 0 1 AD9628 Data Sheet OUTPUT TEST The AD9628 includes various output test options to place predictable values on the outputs of the AD9628. OUTPUT TEST MODES The output test options are described in Table 18 at Address 0x0D. When an output test mode is enabled, the analog section of the ADC is disconnected from the digital back-end blocks and the test pattern is run through the output formatting block. Some of the test patterns are subject to output formatting, and some are not. The PN generators from the PN sequence tests can be reset by setting Bit 4 or Bit 5 of Register 0x0D. These tests can be performed with or without an analog signal (if present, the analog signal is ignored), but they do require an encode clock. For more information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. Rev. C | Page 32 of 42 Data Sheet AD9628 SERIAL PORT INTERFACE (SPI) The AD9628 serial port interface (SPI) allows the user to configure the converter for specific functions or operations through a structured register space provided inside the ADC. The SPI gives the user added flexibility and customization, depending on the application. Addresses are accessed via the serial port and can be written to or read from via the port. Memory is organized into bytes that can be further divided into fields, which are documented in the Memory Map section. For detailed operational information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. The falling edge of the CSB, in conjunction with the rising edge of the SCLK, determines the start of the framing. An example of the serial timing and its definitions can be found in Figure 61 and Table 5. Other modes involving the CSB are available. The CSB can be held low indefinitely, which permanently enables the device; this is called streaming. The CSB can stall high between bytes to allow for additional external timing. When CSB is tied high, SPI functions are placed in high impedance mode. This mode turns on any SPI pin secondary functions. CONFIGURATION USING THE SPI During an instruction phase, a 16-bit instruction is transmitted. Data follows the instruction phase, and its length is determined by the W0 and W1 bits. Three pins define the SPI of this ADC: the SCLK/DFS pin, the SDIO/DCS pin, and the CSB pin (see Table 15). The SCLK/DFS (a serial clock) is used to synchronize the read and write data presented from and to the ADC. The SDIO/DCS (serial data input/output) is a dual-purpose pin that allows data to be sent to and read from the internal ADC memory map registers. The CSB (chip select bar) is an active low control that enables or disables the read and write cycles. In addition to word length, the instruction phase determines whether the serial frame is a read or write operation, allowing the serial port to be used both to program the chip and to read the contents of the on-chip memory. The first bit of the first byte in a multibyte serial data transfer frame indicates whether a read command or a write command is issued. If the instruction is a readback operation, performing a readback causes the serial data input/output (SDIO) pin to change direction from an input to an output at the appropriate point in the serial frame. Table 15. Serial Port Interface Pins Pin SCLK SDIO CSB Function Serial clock. The serial shift clock input, which is used to synchronize serial interface reads and writes. Serial data input/output. A dual-purpose pin that typically serves as an input or an output, depending on the instruction being sent and the relative position in the timing frame. Chip select bar. An active low control that gates the read and write cycles. tHIGH tDS tS tDH All data is composed of 8-bit words. Data can be sent in MSBfirst mode or in LSB-first mode. MSB first is the default on power-up and can be changed via the SPI port configuration register. For more information about this and other features, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. tCLK tH tLOW CSB SCLK DON’T CARE R/W W1 W0 A12 A11 A10 A9 A8 A7 D5 Figure 61. Serial Port Interface Timing Diagram Rev. C | Page 33 of 42 D4 D3 D2 D1 D0 DON’T CARE 09976-046 SDIO DON’T CARE DON’T CARE AD9628 Data Sheet HARDWARE INTERFACE The pins described in Table 15 comprise the physical interface between the user programming device and the serial port of the AD9628. The SCLK pin and the CSB pin function as inputs when using the SPI interface. The SDIO pin is bidirectional, functioning as an input during write phases and as an output during readback. The SPI interface is flexible enough to be controlled by either FPGAs or microcontrollers. One method for SPI configuration is described in detail in the AN-812 Application Note, Microcontroller-Based Serial Port Interface (SPI) Boot Circuit. The SPI port should not be active during periods when the full dynamic performance of the converter is required. Because the SCLK signal, the CSB signal, and the SDIO signal are typically asynchronous to the ADC clock, noise from these signals can degrade converter performance. If the on-board SPI bus is used for other devices, it may be necessary to provide buffers between this bus and the AD9628 to prevent these signals from transitioning at the converter inputs during critical sampling periods. Some pins serve a dual function when the SPI interface is not being used. When the pins are strapped to DRVDD or ground during device power-on, they are associated with a specific function. Table 16 describes the strappable functions supported on the AD9628. CONFIGURATION WITHOUT THE SPI In applications that do not interface to the SPI control registers, the SDIO/DCS pin, the SCLK/DFS pin, the OEB pin, and the PDWN pin serve as standalone CMOS-compatible control pins. When the device is powered up, it is assumed that the user intends to use the pins as static control lines for the duty cycle stabilizer, output data format, and power-down feature control. In this mode, the CSB chip select bar should be connected to AVDD, which disables the serial port interface. When the device is in SPI mode, the PDWN and OEB Pins (if enabled) remain active. For SPI control of output enable and power-down, the OEB and PDWN pins should be set to their default states. Table 16. Mode Selection Pin SDIO/DCS SCLK/DFS OEB PDWN External Voltage DRVDD (default) AGND DRVDD AGND (default) DRVDD AGND (default) DRVDD AGND (default) Configuration Duty cycle stabilizer enabled Duty cycle stabilizer disabled Twos complement enabled Offset binary enabled Outputs in high impedance Outputs enabled Chip in power-down or standby Normal operation SPI ACCESSIBLE FEATURES Table 17 provides a brief description of the general features that are accessible via the SPI. These features are described in detail in the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. The AD9628 part-specific features are described in detail following Table 18, the external memory map register table. Table 17. Features Accessible Using the SPI Feature Name Mode Clock Offset Test I/O Output Mode Output Phase Output Delay Rev. C | Page 34 of 42 Description Allows the user to set either power-down mode or standby mode Allows the user to access the DCS, set the clock divider, set the clock divider phase, and enable the sync Allows the user to digitally adjust the converter offset Allows the user to set test modes to have known data on output bits Allows the user to set the output mode including LVDS Allows the user to set the output clock polarity Allows the user to vary the DCO delay Data Sheet AD9628 MEMORY MAP Default Values READING THE MEMORY MAP REGISTER TABLE Each row in the memory map register table has eight bit locations. The memory map is roughly divided into three sections: the chip configuration registers (Address 0x00 to Address 0x02); the channel index and transfer registers (Address 0x05 and Address 0xFF) and the ADC functions registers, including setup, control, and test (Address 0x08 to Address 0x102). The memory map register table (see Table 18) lists the default hexadecimal value for each hexadecimal address shown. The column with the heading Bit 7 (MSB) is the start of the default hexadecimal value given. For example, Address 0x05, the device index register, has a hexadecimal default value of 0x03. This means that in Address 0x05 Bits[7:2] = 0, and Bits[1:0] = 1. This setting is a default channel index setting. The default value results in both ADC channels receiving the next write command. For more information on this function and others, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. This application note details the functions controlled by Register 0x00 to Register 0xFF. The remaining registers are documented in the Memory Map Register Descriptions section. Open Locations All address and bit locations that are not included in Table 18 are not currently supported for this device. Unused bits of a valid address location should be written with 0s. Writing to these locations is required only when part of an address location is open (for example, Address 0x05). If the entire address location is open (for example, Address 0x13), this address location should not be written to. After the AD9628 is reset, critical registers are loaded with default values. The default values for the registers are given in the memory map register table, Table 18. Logic Levels An explanation of logic level terminology follows: • • “Bit is set” is synonymous with “bit is set to Logic 1” or “writing Logic 1 for the bit.” “Clear a bit” is synonymous with “bit is set to Logic 0” or “writing Logic 0 for the bit.” Channel-Specific Registers Some channel setup functions can be programmed for each channel individually. In these cases, channel address locations are internally duplicated for each channel. These registers and bits are designated in Table 18 as local. These local registers and bits can be accessed by setting the appropriate Channel A or Channel B bits in Register 0x05. If both bits are set, the subsequent write affects the registers of both channels. In a read cycle, only Channel A or Channel B should be set to read one of the two registers. If both bits are set during an SPI read cycle, the part returns the value for Channel A. Registers and bits designated as global in Table 18 affect the entire part or the channel features for which independent settings are not allowed between channels. Rev. C | Page 35 of 42 AD9628 Data Sheet MEMORY MAP REGISTER TABLE All address and bit locations that are not included in Table 18 are not currently supported for this device. Table 18. Memory Map Registers Addr Register Bit 7 (Hex) Name (MSB) Chip Configuration Registers 0x00 SPI port Open config (global) 0x01 Chip ID (global) 0x02 Chip grade (global) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (LSB) Default Value (Hex) LSB first Soft reset 1 1 Soft reset LSB first Open 0x18 8-bit chip ID[7:0] AD9628 = 0x89 Open Read only Speed grade ID 100 = 105 MSPS 101 = 125 MSPS Open Read only Channel Index and Transfer Registers 0x05 Device Open Open index (global) Open Open Open Open Data Channel B Data Channel A 0x03 0xFF Transfer 0x00 Transfer (global) Open Open Open Open Open Open Open ADC Functions 0x08 Power modes (local) Open Open Open Open Open Internal power-down mode 00 = normal operation 01 = full power-down 10 = standby 11 = digital reset 0x00 0x09 Global clock (global) Open Open External powerdown pin function 0 = PDWN 1 = standby Open Open Open Open Open 0x01 0x0B Clock divide (global) Open Open Open Open Open Rev. C | Page 36 of 42 Clock divide ratio 000 = divide by 1 001 = divide by 2 010 = divide by 3 011 = divide by 4 100 = divide by 5 101 = divide by 6 110 = divide by 7 111 = divide by 8 Duty cycle stabilizer 0= disabled 1= enabled 0x00 Comments The nibbles are mirrored so LSB-first mode or MSB-first mode registers correctly, regardless of shift mode Unique Chip ID used to differentiate devices; read only Unique speed grade ID used to differentiate devices; read only Bits are set to determine which device on the chip receives the next write command; applies to local registers only Synchronously transfers data from the master shift register to the slave Determines various generic modes of chip operation The divide ratio is value plus 1 Data Sheet AD9628 Addr (Hex) 0x0C Register Name Enhancement control (global) Bit 7 (MSB) Open 0x0D Test mode (local) User test mode control 00 = single pattern mode 01 = alternate continuous/repeat pattern mode 10 = single once pattern mode 11 = alternate once pattern mode 0x10 Customer offset adjust (local) Output mode 0x14 Bit 6 Open Output port logic type (global) 00 = CMOS, 1.8 V 10 = LVDS, ANSI 11 = LVDS, reduced range Open Open Bit 5 Open Reset PN long gen Output interleave enable (global) Bit 4 Open Bit 3 Open Bit 2 Bit 1 Bit 0 (LSB) Chop Open Open 0= disabled 1= enabled Reset PN Output test mode short gen 0000 = off (default) 0001 = midscale short 0010 = positive FS 0011 = negative FS 0100 = alternating checkerboard 0101 = PN long sequence 0110 = PN short sequence 0111 = one/zero word toggle 1000 = user test mode 1111 = ramp output Offset adjust in LSBs from +127 to −128 (twos complement format) Output port disable (local) Open (global) Output invert (local) CMOS 1.8 V DCO drive strength 00 = 1× 01 = 2× 10 = 3× 11 = 4× Open Open Open Open Output format 00 = offset binary 01 = twos complement 10 = Gray code Default Value (Hex) 0x00 0x00 Comments Chop mode enabled if Bit 2 is enabled. When this register is set, the test data is placed on the output pins in place of normal data 0x00 0x00 Configures the outputs and the format of the data 0x00 Determines CMOS output drive strength properties 0x00 Allows selection of clock delays into the input clock divider 0x00 This sets the fine output delay of the output clock but does not change internal timing 0x04 Select and/or adjust VREF 0x00 User-defined Pattern 1 LSB 0x15 Output adjust 0x16 Clock phase control (global) Invert DCO clock 0 = not inverted 1= inverted Open 0x17 Output delay (global) DCO Clock delay 0= disabled 1= enabled Open Data delay 0= disabled 1= enabled Open Open 0x18 VREF select (global) Open Open Open Open Open 0x19 User Pattern 1 LSB (global) User Pattern 1 MSB (global) User Pattern 2 LSB (global) B7 B6 B5 B4 B3 CMOS 1.8 V data drive strength 00 = 1× 01 = 2× 10 = 3× 11 = 4× Input clock divider phase adjust relative to the encode clock 000 = no delay 001 = one input clock cycle 010 = two input clock cycles 011 = three input clock cycles 100 = four input clock cycles 101 = five input clock cycles 110 = six input clock cycles 111 = seven input clock cycles Delay selection 000 = 0.56 ns 001 = 1.12 ns 010 = 1.68 ns 011 = 2.24 ns 100 = 2.80 ns 101 = 3.36 ns 110 = 3.92 ns 111 = 4.48 ns Internal VREF digital adjustment 000 = 1.0 V p-p 001 = 1.14 V p-p 010 = 1.33 V p-p 011 = 1.6 V p-p 100 = 2.0 V p-p B2 B1 B0 B15 B14 B13 B12 B11 B10 B9 B8 0x00 User-defined pattern, 1 MSB B7 B6 B5 B4 B3 B2 B1 B0 0x00 User-defined pattern 2 LSBs 0x1A 0x1B Open Rev. C | Page 37 of 42 AD9628 Addr (Hex) 0x1C Data Sheet Register Name User pattern MSB Overrange control (global) Bit 7 (MSB) B15 Bit 6 B14 Bit 5 B13 Bit 4 B12 Bit 3 B11 Bit 2 B10 Bit 1 B9 Bit 0 (LSB) B8 Open Open Open Open Open Open Open 0x2E Output assign (local) Open Open Open Open Open Open Open Overrange output 0 = disabled 1 = enabled 0 = ADC A 1 = ADC B (local) 0x3A Sync control (global) Open Open Open Open Open Clock divider next sync only 0x100 Sample rate override Open Sample rate override enable 0x101 User I/O Control Register 2 Open Open Open Open 0x102 User I/O Control Register 3 Output Enable Bar (OEB) pin enable Open Open Open Open VCM powerdown 0x2A Resolution 100 = 12 bits 110 = 10 bits Rev. C | Page 38 of 42 Open Clock Open divider sync enable Sample rate 011 = 80 MSPS 100 = 105 MSPS 101 = 125 MSPS Open Disable SDIO pulldown Open Default Value (Hex) 0x00 0x01 ADC A = 0x00 ADC B = 0x01 0x00 Comments User-defined pattern, 2 MSBs Overrange control settings Assigns an ADC to an output channel Sets the global sync options 0x00 0x80 0x00 OEB and SDIO pin controls Data Sheet AD9628 MEMORY MAP REGISTER DESCRIPTIONS For additional information about functions controlled in Register 0x00 to Register 0xFF, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. interleaving feature. Channel A is sent on least significant bits (LSBs), and Channel B is sent on most significant bits (MSBs). The even bits are sent coincident with a high DCO clock, and the odd bits are sent coincident with a low DCO clock. Bits[4:2]—Open For CMOS outputs, setting Bit 5 enables interleaving in CMOS DDR mode. On ADC Output Port A, Channel A is sent coincident with a low DCO clock, and Channel B is coincident with a high DCO clock. On ADC Output Port B, Channel B is sent coincident with a low DCO clock, and Channel A is coincident with a high DCO clock. Clearing Bit 5 disables the interleaving feature, and data is output in CMOS SDR mode. Channel A is sent to Port A, and Channel B is sent to Port B. Bits[1:0]—Internal Power-Down Mode Bit 4—Output Port Disable In normal operation (Bits[1:0] = 00), both ADC channels are active. Setting Bit 4 high disables the output port for the channels selected in Bits[1:0] of the device index register (Register 0x05). In power-down mode (Bits[1:0] = 01), the digital data path clocks are disabled while the digital data path is reset. Outputs are disabled. Bit 3—Open Power Modes (Register 0x08) Bits[7:6]—Open Bit 5—External Power-Down Pin Function If set, the external PDWN pin initiates power-down mode. If clear, the external PDWN pin initiates standby mode. In standby mode (Bits[1:0] = 10), the digital data path clocks and the outputs are disabled. During a digital reset (Bits[1:0] = 11), the digital data path clocks are disabled while the digital data path is held in reset. The outputs are enabled in this state. For optimum performance, it is recommended that both ADC channels be reset simultaneously. This is accomplished by ensuring that both channels are selected via Register 0x05 prior to issuing the digital reset instruction. Enhancement Control (Register 0x0C) Bits[7:3]—Open Bit 2—Output Invert Setting Bit 2 high inverts the output port data for the channels selected in Bits[1:0] of the device index register (Register 0x05). Bits[1:0]—Output Format 00 = offset binary 01 = twos complement 10 = Gray code Sync Control (Register 0x3A) Bits[7:3]—Open Bit 2—Clock Divider Next Sync Only Bit 2—Chop Mode For applications that are sensitive to offset voltages and other low frequency noise, such as homodyne or direct-conversion receivers, chopping in the first stage of the AD9628 is a feature that can be enabled by setting Bit 2. In the frequency domain, chopping translates offsets and other low frequency noise to fCLK/2 where it can be filtered. Bits[1:0]—Open If the clock divider sync enable bit (Address 0x3A, Bit 1) is high, Bit 2 allows the clock divider to sync to the first sync pulse it receives and to ignore the rest. The clock divider sync enable bit resets after it syncs. Bit 1—Clock Divider Sync Enable Bit 1 gates the sync pulse to the clock divider. The sync signal is enabled when Bit 1 is high. This is continuous sync mode. Bit 0—Open Transfer (Register 0xFF) Output Mode (Register 0x14) Bits[7:6]—Output Port Logic Type All registers except Register 0x100 are updated the moment they are written. Setting Bit 0 of this transfer register high initializes the settings in the ADC sample rate override register (Address 0x100). 00 = CMOS, 1.8 V 10 = LVDS, ANSI 11 = LVDS, reduced range Sample Rate Override (Register 0x100) Bit 5—Output Interleave Enable For LVDS outputs, setting Bit 5 enables interleaving. Channel A is sent coincident with a high DCO clock, and Channel B is coincident with a low DCO clock. Clearing Bit 5 disables the This register is designed to allow the user to downgrade the device. Any attempt to upgrade the default speed grade results in a chip power-down. Settings in this register are not initialized until Bit 0 of the transfer register (Register 0xFF) is written high. Rev. C | Page 39 of 42 AD9628 Data Sheet User I/O Control 2 (Register 0x101) Bit 7—OEB Pin Enable User I/O Control 3 (Register 0x102) Bits[7:4]—Open If the OEB pin enable bit (Bit 7) is set (default), the OEB pin is enabled. If Bit 7 is clear, the OEB pin is disabled. Bit 3—VCM Power-Down Bits[6:1]—Open Bit 0—SDIO Pull-Down Bit 0 can be set to disable the internal 30 kΩ pull-down on the SDIO pin, which can be used to limit the loading when many devices are connected to the SPI bus. Bit 3 can be set high to power down the internal VCM generator. This feature is used when applying an external reference. Bits[2:0]—Open Rev. C | Page 40 of 42 Data Sheet AD9628 APPLICATIONS INFORMATION DESIGN GUIDELINES Before starting design and layout of the AD9628 as a system, it is recommended that the designer become familiar with these guidelines, which discuss the special circuit connections and layout requirements that are needed for certain pins. Power and Ground Recommendations When connecting power to the AD9628, it is recommended that two separate 1.8 V supplies be used. Use one supply for analog (AVDD); use a separate supply for the digital outputs (DRVDD). For both AVDD and DRVDD, several different decoupling capacitors should be used to cover both high and low frequencies. Place these capacitors close to the point of entry at the PCB level and close to the pins of the part, with minimal trace length. A single PCB ground plane should be sufficient when using the AD9628. With proper decoupling and smart partitioning of the PCB analog, digital, and clock sections, optimum performance is easily achieved. LVDS Operation The AD9628 defaults to CMOS output mode on power-up. If LVDS operation is desired, this mode must be programmed, using the SPI configuration registers after power-up. When the AD9628 powers up in CMOS mode with LVDS termination resistors (100 Ω) on the outputs, the DRVDD current can be higher than the typical value until the part is placed in LVDS mode. This additional DRVDD current does not cause damage to the AD9628, but it should be taken into account when considering the maximum DRVDD current for the part. To avoid this additional DRVDD current, the AD9628 outputs can be disabled at power-up by taking the PDWN pin high. After the part is placed into LVDS mode via the SPI port, the PDWN pin can be taken low to enable the outputs. Clock Stability Considerations When powered on, the AD9628 enters an initialization phase during which an internal state machine sets up the biases and the registers for proper operation. During the initialization process, the AD9628 needs a stable clock. If the ADC clock source is not present or not stable during ADC power-up, it disrupts the state machine and causes the ADC to start up in an unknown state. To correct this, an initialization sequence must be reinvoked after the ADC clock is stable by issuing a digital reset via Register 0x08. In the default configuration (internal VREF, ac-coupled input) where VREF and VCM are supplied by the ADC itself, a stable clock during power-up is sufficient. In the case where VREF and/or VCM are supplied by an external source, these, too, must be stable at power-up; otherwise, a subsequent digital reset via Register 0x08 is needed. Interruption of the sample clock during operation and changes in sample rate also necessitate a digital reset. The pseudo code sequence for a digital reset is as follows: SPI_Write (0x08, 0x03); # Digital Reset SPI_Write (0x08, 0x00); # Can be asserted as soon as the next SPI cycle, normal operation resumes after 2.9e6 sample clock cycles, ADC outputs 0s until the reset is complete. Exposed Paddle Thermal Heat Slug Recommendations It is mandatory that the exposed paddle on the underside of the ADC be connected to analog ground (AGND) to achieve the best electrical and thermal performance. A continuous, exposed (no solder mask) copper plane on the PCB should mate to the AD9628 exposed paddle, Pin 0. The copper plane should have several vias to achieve the lowest possible resistive thermal path for heat dissipation to flow through the bottom of the PCB. These vias should be filled or plugged to prevent solder wicking through the vias, which can compromise the connection. To maximize the coverage and adhesion between the ADC and the PCB, a silkscreen should be overlaid to partition the continuous plane on the PCB into several uniform sections. This provides several tie points between the ADC and the PCB during the reflow process. Using one continuous plane with no partitions guarantees only one tie point between the ADC and the PCB. For detailed information about packaging and PCB layout of chip scale packages, see the AN-772 Application Note, A Design and Manufacturing Guide for the Lead Frame Chip Scale Package (LFCSP). VCM The VCM pin should be decoupled to ground with a 0.1 μF capacitor. Reference Decoupling The VREF pin should be externally decoupled to ground with a low ESR, 1.0 μF capacitor in parallel with a low ESR, 0.1 μF ceramic capacitor. SPI Port The SPI port should not be active during periods when the full dynamic performance of the converter is required. Because the SCLK, CSB, and SDIO signals are typically asynchronous to the ADC clock, noise from these signals can degrade converter performance. If the on-board SPI bus is used for other devices, it may be necessary to provide buffers between this bus and the AD9628 to keep these signals from transitioning at the converter inputs during critical sampling periods. Rev. C | Page 41 of 42 AD9628 Data Sheet OUTLINE DIMENSIONS 9.10 9.00 SQ 8.90 0.60 0.42 0.24 0.60 0.42 0.24 48 0.30 0.23 0.18 64 1 49 PIN 1 INDICATOR PIN 1 INDICATOR 8.85 8.75 SQ 8.65 0.50 BSC 0.50 0.40 0.30 33 32 SEATING PLANE 0.25 MIN 7.50 REF 0.05 MAX 0.02 NOM 0.20 REF PKG-1184 16 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-VMMD-4 01-22-2015-D 0.80 MAX 0.65 NOM 12° MAX 17 BOTTOM VIEW TOP VIEW 1.00 0.85 0.80 6.35 6.20 SQ 6.05 EXPOSED PAD Figure 62. 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 9 mm × 9 mm Body, Very Thin Quad (CP-64-4) Dimensions shown in millimeters ORDERING GUIDE Model 1 AD9628BCPZ-105 AD9628BCPZ-125 AD9628BCPZRL7-105 AD9628BCPZRL7-125 AD9628-125EBZ 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board Z = RoHS Compliant Part. ©2011–2015 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09976-0-11/15(C) Rev. C | Page 42 of 42 Package Option CP-64-4 CP-64-4 CP-64-4 CP-64-4