ADT7463ARQ

ADT7463 Remote Thermal Controller and Voltage Monitor The ADT7463 controller is a complete systems monitor and multiple PWM fan controller for noise−sensitive applications requiring active system cooling. It can monitor 12 V, 5 V, and 2.5 V CPU supply voltages, plus its own supply voltage. It can monitor the temperature of up to two remote sensor diodes, plus its own internal temperature. It can measure and control the speed of up to four fans so that they operate at the lowest possible speed for minimum acoustic noise. The automatic fan speed control loop optimizes fan speed for a given temperature. A unique dynamic TMIN control mode enables the system thermals/acoustics to be intelligently managed. The effectiveness of the system’s thermal solution can be monitored using the THERM input. The ADT7463 also provides critical thermal protection to the system using the bidirectional THERM pin as an output to prevent system or component overheating. Features • • • • • • • • • • • • • Monitors Up to 5 Supply Voltages Controls and Monitors up to 4 Fan Speeds 1 On−Chip and 2 Remote Temperature Sensors Monitors Up to 6 Processor VID Bits Dynamic TMIN Control Mode Optimizes System Acoustics Intelligently Automatic Fan Speed Control Mode Controls System Cooling Based on Measured Temperature Enhanced Acoustic Mode Dramatically Reduces User Perception of Changing Fan Speeds Thermal Protection Feature via THERM Output Monitors Performance Impact of Intel® Pentium® 4 Processor Thermal Control Circuit via THERM Input 2−wire and 3−wire Fan Speed Measurement Limit Comparison of All Monitored Values Meets SMBus 2.0 Electrical Specifications (Fully SMBus 1.1 Compliant) This is a Pb−Free Device http://onsemi.com QSOP24 NB CASE 492B PIN ASSIGNMENT SDA 1 24 PWM1/XTO SCL 2 23 VCCP GND 3 22 VCC 4 +2.5VIN/ SMBALERT 21 +12VIN/VID5 VID0 5 20 +5VIN/THERM VID1 6 VID2 7 VID3 8 17 D1− TACH3 9 PWM2/ 10 SMBALERT TACH1 11 16 D2+ ADT7463 19 VID4 18 D1+ 15 D2− TACH4/ADDR SELECT/THERM 13 PWM3/ADDRESS ENABLE 14 TACH2 12 (Top View) MARKING DIAGRAM ADT7463A RQZ#YYWW Applications • Low Acoustic Noise PCs • Networking and Telecommunications Equipment ADT7463ARQZ # YY WW = Specific Device Code = Pb−Free Package = Date Code = Work Week ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 49 of this data sheet. © Semiconductor Components Industries, LLC, 2013 May, 2013 − Rev. 7 1 Publication Order Number: ADT7463/D ADT7463 ADDR SELECT ADDR EN SCL SDA SMBALERT VID5 VID4 VID3 VID2 VID REGISTER SMBUS ADDRESS SELECTION VID1 VID0 PWM1 PWM2 PWM3 PWM REGISTERS AND CONTROLLERS ACOUSTIC ENHANCEMENT CONTROL TACH1 TACH2 SERIAL BUS INTERFACE AUTOMATIC FAN SPEED CONTROL ADDRESS POINTER REGISTER DYNAMIC TMIN CONTROL PWM CONFIGURATION REGISTERS FAN SPEED COUNTER TACH3 INTERRUPT MASKING TACH4 PERFORMANCE MONITORING THERMAL PROTECTION THERM VCC D1+ VCC TO ADT7463 D1− D2+ ADT7463 10−BIT ADC INPUT SIGNAL CONDITIONING AND ANALOG MULTIPLEXER D2− VCC +5VIN +12VIN +2.5VIN BAND GAP REFERENCE VCCP BAND GAP TEMP. SENSOR GND Figure 1. Functional Block Diagram http://onsemi.com 2 INTERRUPT STATUS REGISTERS LIMIT COMPARATORS VALUE AND LIMIT REGISTERS ADT7463 Table 1. ABSOLUTE MAXIMUM RATINGS Parameter Rating Unit 6.5 V Positive Supply Voltage (VCC) Voltage on +12VIN Pin 20 V −0.3 to +6.5 V Input Current at Any Pin ±5 mA Package Input Current ±20 mA Maximum Junction Temperature (TJ MAX) 150 °C −65 to +150 °C Voltage on Any Input or Output Pin Storage Temperature Range Lead Temperature, Soldering IR Reflow Peak Temperature IR Reflow Peak Temperature for Pb−Free Lead Temperature (Soldering, 10 sec) °C 220 260 300 ESD Rating 1500 V Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Table 2. THERMAL CHARACTERISTICS Package Type 24−lead QSOP qJA qJC Unit 105 39 °C/W Table 3. PIN ASSIGNMENT Pin No. Mnemonic Description 1 SDA Digital I/O (Open Drain). SMBus bidirectional serial data. Requires SMBus. 2 SCL Digital Input (Open Drain). SMBus serial clock input. Requires SMBus pull−up. 3 GND Ground Pin for the ADT7463. 4 VCC Power Supply. Can be powered by 3.3 V standby if monitoring in low power states is required. VCC is also monitored through this pin. The ADT7463 can also be powered from a 5 V supply. Setting Bit 7 of Configuration Register 1 (Reg. 0x40) rescales the VCC input attenuators to correctly measure a 5 V supply. 5 VID0 Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). 6 VID1 Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). 7 VID2 Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). 8 VID3 Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). 9 TACH3 Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 3. Can be reconfigured as an analog input (AIN3) to measure the speed of 2−wire fans. 10 PWM2 Digital Output (Open Drain). Requires 10 kW typical pull−up. Pulse−width modulated output to control FAN 2 speed. Digital Output (Open Drain). This pin may be reconfigured as an SMBALERT interrupt output to signal out−of−limit conditions. SMBALERT 11 TACH1 Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 1. Can be reconfigured as an analog input (AIN1) to measure the speed of 2−wire fans. 12 TACH2 Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 2. Can be reconfigured as an analog input (AIN2) to measure the speed of 2−wire fans. 13 PWM3 Digital I/O (Open Drain). Pulse−width modulated output to control Fan 3/Fan 4 speed. Requires 10 kW typical pull−up. If pulled low on power−up, this places the ADT7463 into address select mode, and the state of Pin 14 will determine the ADT7463’s slave address. ADDRESS ENABLE http://onsemi.com 3 ADT7463 Table 3. PIN ASSIGNMENT Pin No. 14 Mnemonic TACH4 Description ADDRESS SELECT THERM Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 4. Can be reconfigured as an analog input (AIN4) to measure the speed of 2−wire fans. If in address select mode, this pin determines the SMBus device address. Alternatively, the pin may be reconfigured as a bidirectional THERM pin. Can be used to time and monitor assertions on the THERM input. For example, can be connected to the PROCHOT output of Intel’s Pentium® 4 processor or to the output of a trip point temperature sensor. Can be used as an output to signal overtemperature conditions. 15 D2– Cathode Connection to Second Thermal Diode. 16 D2+ Anode Connection to Second Thermal Diode. 17 D1– Cathode Connection to First Thermal Diode. 18 D1+ Anode Connection to First Thermal Diode. 19 VID4 Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). 20 +5VIN THERM Analog Input. Monitors 5 V power supply. Alternatively, this pin may be reconfigured as a bidirectional THERM pin. Can be used to time and monitor assertions on the THERM input. For example, can be connected to the PROCHOT output of Intel’s Pentium® 4 processor or to the output of a trip point temperature sensor. Can be used as an output to signal overtemperature conditions. 21 +12VIN VID5 Analog Input. Monitors 12 V power supply. Digital Input (Open Drain). Voltage supply readouts from CPU. This value is read into the VID register (Reg. 0x43). Supports VRM10 solutions. 22 +2.5VIN SMBALERT Analog Input. Monitors 2.5 V supply, typically a chipset voltage. Digital Output (Open Drain). This pin may be reconfigured as an SMBALERT interrupt output to signal out−of−limit conditions. 23 VCCP Analog Input. Monitors processor core voltage (0 V to 3 V). 24 PWM1 Digital Output (Open Drain). Pulse−width modulated output to control Fan 1 speed. Requires 10 kW typical pull−up. Also functions as the output from the XOR tree in XOR test mode. XTO Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted.) (Notes 1, 2, 3, 4) Parameter Test Conditions/Comments Min Typ Max Unit POWER SUPPLY 3.0 5.0 5.5 V Interface Inactive, ADC Active Standby Mode − − − − 3.0 20 mA mA 0°C ≤ TA ≤ 70°C −40°C ≤ TA ≤ +120°C − − ±0.5 − ±1.5 ±3.0 °C − 0.25 − °C − − − ±0.5 − − ±1.5 ±2.5 ±3.0 °C − 0.25 − °C − − 180 11 − − mA Total Unadjusted Error, TUE − − ±1.5 % Differential Non−linearity, DNL − − ±1.0 LSB Power Supply Sensitivity − ±0.1 − %/V Supply Voltage Supply Current, ICC TEMPERATURE−TO−DIGITAL CONVERTER Local Sensor Accuracy Resolution Remote Diode Sensor Accuracy 0°C ≤ TA ≤ 70°C; 0°C ≤ TD ≤ 120°C 0°C ≤ TA ≤ 105°C; 0°C ≤ TD ≤ 120°C 0°C ≤ TA ≤ 120°C; 0°C ≤ TD ≤ 120°C Resolution Remote Sensor Source Current High Level Low Level ANALOG−TO−DIGITAL CONVERTER (INCLUDING MUX AND ATTENUATORS) Conversion Time (Voltage Input) Averaging Enabled − 11.38 13 ms Conversion Time (Local Temperature) Averaging Enabled − 12.09 13.50 ms Conversion Time (Remote Temperature) Averaging Enabled − 25.59 28 ms Total Monitoring Cycle Time Averaging Enabled Averaging Disabled − − 120.17 13.51 134.50 15 ms http://onsemi.com 4 ADT7463 Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted.) (Notes 1, 2, 3, 4) Parameter Test Conditions/Comments Min Typ Max Unit 100 140 200 kW − − − − − − ±7 ±11 ±13 % − − 65,535 − − − − 109 329 5,000 10,000 − − − − RPM 82.8 90.0 97.2 kHz mA ANALOG−TO−DIGITAL CONVERTER (INCLUDING MUX AND ATTENUATORS) Input Resistance FAN RPM−TO−DIGITAL CONVERTER Accuracy 0°C ≤ TA ≤ 70°C 0°C ≤ TA ≤ 105°C −40°C ≤ TA ≤ +120°C Full−scale Count Nominal Input RPM Fan Count = 0xBFFF Fan Count = 0x3FFF Fan Count = 0x0438 Fan Count = 0x021C Internal Clock Frequency OPEN−DRAIN DIGITAL OUTPUTS, PWM1 TO PWM3, XTO − − 8.0 Output Low Voltage, VOL IOUT = −8.0 mA, VCC = 3.3 V − − 0.4 V High Level Output Current, IOH VOUT = VCC − 0.1 1.0 mA Current Sink, IOL OPEN−DRAIN SERIAL DATA BUS OUTPUT (SDA) Output Low Voltage, VOL IOUT = −4.0 mA, VCC = 3.3 V − − 0.4 V High Level Output Current, IOH VOUT = VCC − 0.1 1.0 mA Input High Voltage, VIH 2.0 − − V Input Low Voltage, VIL − − 0.4 V Hysteresis − 500 − mV SMBUS DIGITAL INPUTS (SCL, SDA) DIGITAL INPUT LOGIC LEVELS (VID0 TO VID5) Input High Voltage, VIH Bit 6 (THLD) Reg. 0x43 = 0 (VID Threshold = 1 V) 1.7 − − V Input Low Voltage, VIL Bit 6 (THLD) Reg. 0x43 = 0 (VID Threshold = 1 V) − − 0.8 V Input High Voltage, VIH Bit 6 (THLD) Reg. 0x43 = 1 (VID Threshold = 0.6 V) 0.8 − − V Input Low Voltage, VIL Bit 6 (THLD) Reg. 0x43 = 1 (VID Threshold = 0.6 V) − − 0.4 V Maximum Input Voltage 2.0 − − − − 5.5 V Minimum Input Voltage − −0.3 − − +0.8 − V − 0.5 − V p−p Input High Voltage, VIH − 0.75 × VCCP − V Input Low Voltage, VIL − − 0.4 V −1.0 − − mA − − +1.0 mA − 5.0 − pF DIGITAL INPUT LOGIC LEVELS (TACH INPUTS) Input High Voltage, VIH Input Low Voltage, VIL Hysteresis DIGITAL INPUT LOGIC LEVELS (THERM) AGTL+ DIGITAL INPUT CURRENT Input High Current, IIH VIN = VCC Input Low Current, IIL VIN = 0 Input Capacitance, CIN http://onsemi.com 5 ADT7463 Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted.) (Notes 1, 2, 3, 4) Parameter Test Conditions/Comments Min Typ Max Unit − − 400 kHz SERIAL BUS TIMING (Note 5) Clock Frequency, fSCLK See Figure 2 Glitch Immunity, tSW See Figure 2 − − 50 ns Bus Free Time, tBUF See Figure 2 1.3 − − ms Start Setup Time, tSU;STA See Figure 2 0.6 − − ms Start Hold Time, tHD;STA See Figure 2 0.6 − − ms SCL Low Time, tLOW See Figure 2 1.3 − − ms SCL High Time, tHIGH See Figure 2 0.6 − 50 ms SCL, SDA Rise Time, tR See Figure 2 − − 1,000 ns SCL, SDA Fall Time, tF See Figure 2 − − 300 ms Data Setup Time, tSU;DAT See Figure 2 100 − − ns Data Hold Time, tHD;DAT See Figure 2 300 − − ns Detect Clock Low Timeout, tTIMEOUT Can be Optionally Disabled 15 − 35 ms 1. All voltages are measured with respect to GND, unless otherwise specified. 2. Typicals are at TA = 25°C and represent the most likely parametric norm. 3. Logic inputs accept input high voltages up to VMAX even when the device is operating down to VMIN. 4. Timing specifications are tested at logic levels of VIL = 0.8 V for a falling edge and VIH = 2.0 V for a rising edge. 5. Guaranteed by design; not production tested NOTE: Specifications subject to change without notice. t LOW tF t HD; STA tR SCL t HD; STA t HD; DAT t HIGH t SU; STA t SU; DAT t SU; STO SDA P t BUF S S Figure 2. Serial Bus Timing Diagram http://onsemi.com 6 P ADT7463 15 10 REMOTE TEMPERATURE ERROR (°C) REMOTE TEMPERATURE ERROR (°C) TYPICAL PERFORMANCE CHARACTERISTICS DXP To GND 5 0 −5 DXP To VCC (3.3 V) −10 −15 −20 1.0 3.3 10.0 30.0 100.0 3 0 −3 −6 −9 −12 −15 −18 −21 −24 −27 −30 −33 −36 1.0 3 HIGH LIMIT +3 SIGMA 0 −3 SIGMA −1 LOW LIMIT −2 −3 −40 10 60 2 LOCAL TEMPERATURE ERROR (°C) REMOTE TEMPERATURE ERROR (°C) 10 8 250 mV 4 2 100 mV 5M 47.0 HIGH LIMIT +3 SIGMA 0 −3 SIGMA −1 LOW LIMIT −2 −3 −40 10 60 110 Figure 6. Local Temperature Error vs. Actual Temperature 12 550K 22.0 TEMPERATURE (°C) 14 −2 100K 10.0 1 110 Figure 5. Remote Temperature Error vs. Actual Temperature 0 4.7 3 TEMPERATURE (°C) 6 3.3 Figure 4. Remote Temperature Error vs. Capacitance between D+ and D− LOCAL TEMPERATURE ERROR (°C) REMOTE TEMPERATURE ERROR (°C) Figure 3. Remote Temperature Error vs. Leakage Resistance 1 2.2 DXP TO DXN CAPACITANCE (nF) LEAKAGE RESISTANCE (MW) 2 REMOTE TEMPERATURE ERROR (°C) 50M 12.5 10.0 7.5 250 mV 5.0 2.5 0 100 mV −2.5 −5.0 100K 550K 5M 50M FREQUENCY (Hz) FREQUENCY (Hz) Figure 7. Remote Temperature Error vs. Power Supply Noise Frequency Figure 8. Local Temperature Error vs. Power Supply Noise Frequency http://onsemi.com 7 ADT7463 TYPICAL PERFORMANCE CHARACTERISTICS (Cont’d) SUPPLY CURRENT (mA) 1.9 1.8 1.7 1.6 1.5 1.4 2.6 3.0 3.4 3.8 4.2 4.6 5.0 5.4 SUPPLY VOLTAGE (V) REMOTE TEMPERATURE ERROR (°C) Figure 9. Supply Current vs. Supply Voltage 16 14 20 mV 12 10 8 10 mV 6 4 2 0 −2 60K 110K 1M 10M 50M FREQUENCY (Hz) REMOTE TEMPERATURE ERROR (°C) Figure 10. Remote Temperature Error vs. Differential−Mode Noise Frequency 40 35 100 mV 30 25 20 15 10 40 mV 5 0 20 mV −5 −10 10K 100K 1M FREQUENCY (Hz) Figure 11. Remote Temperature Error vs. Common−Mode Noise Frequency http://onsemi.com 8 10M ADT7463 Functional Description ADT7463 Address Selection Pin 13 is the dual−function PWM3/ADDRESS ENABLE pin. If Pin 13 is pulled low on power−up, the ADT7463 reads the state of Pin 14 (TACH4/ADDRESS SELECT/ THERM pin) to determine the ADT7463’s slave address. If Pin 13 is high on power−up, then the ADT7463 defaults to the SMBus slave Address 0x2E. This function is described in more detail later. General Description The ADT7463 is a complete systems monitor and multiple fan controller for any system requiring monitoring and cooling. The device communicates with the system via a serial system management bus. The serial bus controller has an optional address line for device selection (Pin 14), a serial data line for reading and writing addresses and data (Pin 1), and an input line for the serial clock (Pin 2). All control and programming functions of the ADT7463 are performed over the serial bus. In addition, two of the pins can be reconfigured as an SMBALERT output to indicate out−of−limit conditions. Internal Registers of the ADT7463 A brief description of the ADT7463’s principal internal registers is given below. More detailed information on the function of each register is given in Tables X4 to X42. Configuration Registers The configuration registers provide control and configuration of the ADT7463, including alternate pinout functionality. Measurement Inputs The device has six measurement inputs, four for voltage and two for temperature. It can also measure its own supply voltage and can measure ambient temperature with its on−chip temperature sensor. Pins 20 through 23 are analog inputs with on−chip attenuators, configured to monitor 5 V, 12 V, 2.5 V, and the processor core voltage (2.25 V input), respectively. Power is supplied to the chip via Pin 4, and the system also monitors VCC through this pin. In PCs, this pin is normally connected to a 3.3 V standby supply. This pin can, however, be connected to a 5 V supply and monitor it without overranging. Remote temperature sensing is provided by the D1± and D2± inputs, to which diode−connected, external temperature−sensing transistors, such as a 2N3904 or CPU thermal diode, may be connected. The ADC also accepts input from an on−chip band gap temperature sensor that monitors system ambient temperature. Address Pointer Register This register contains the address that selects one of the other internal registers. When writing to the ADT7463, the first byte of data is always a register address, which is written to the address pointer register. Status Registers These registers provide the status of each limit comparison and are used to signal out−of−limit conditions on the temperature, voltage, or fan speed channels. If Pin 10 or Pin 22 is configured as SMBALERT, then this pin asserts low whenever a status bit gets set. Interrupt Mask Registers These registers allow each interrupt status event to be masked when Pin 10 or Pin 22 is configured as an SMBALERT output. Sequential Measurement VID Register When the ADT7463 monitoring sequence is started, it cycles sequentially through the measurement of analog inputs and the temperature sensors. Measured values from these inputs are stored in value registers. These can be read out over the serial bus or can be compared with programmed limits stored in the limit registers. The results of out−of−limit comparisons are stored in the status registers, which can be read over the serial bus to flag out−of−limit conditions. The status of the VID0 to VID5 pins of the processor can read from this register. VID code changes can also generate SMBALERT interrupts. Value and Limit Registers The results of analog voltage inputs, temperature, and fan speed measurements are stored in these registers, along with their limit values. Offset Registers These registers allow each temperature channel reading to be offset by a twos complement value written to these registers. Processor Voltage ID Five digital inputs (VID0 to VID5 − Pins 5 to 8, 19, and 21) read the processor voltage ID code and store it in the VID register, from which it can be read out by the management system over the serial bus. The VID code monitoring function is compatible with both VRM9.x and future VRM10 solutions. Additionally, an SMBALERT can be generated to flag a change in VID code. TMIN Registers These registers program the starting temperature for each fan under automatic fan speed control. http://onsemi.com 9 ADT7463 • VCC Measured Internally Through Pin 4 • CPU Core Voltage Measurement (VCORE) • 2.5 V Measurement Input Used to Monitor CPU TRANGE Registers These registers program the temperature−to−fan speed control slope in automatic fan speed control mode for each PWM output. Current (Connected to VCOMP Output of ADP316x VRM Controller) This Is Used to Determine CPU Power Consumption 5 V Measurement Input VRM Temperature Uses Local Temperature Sensor CPU Temperature Measured Using Remote 1 Temperature Channel Ambient Temperature Measured Through Remote 2 Temperature Channel If Not Using VID5, This Pin Can Be Reconfigured as the 12 V Monitoring Input Bidirectional THERM Pin. Allows Intel® Pentium® 4 PROCHOT Monitoring and Can Function as an Overtemperature THERM Output SMBALERT System Interrupt Output Operating Point Registers These registers define the target operating temperatures for each thermal zone when running under dynamic TMIN control. This function allows the cooling solution to adjust dynamically in response to measured temperature and system performance. • • • Enhance Acoustics Registers • These registers allow each PWM output controlling fan to be tweaked to enhance the system’s acoustics. • Recommended Implementation Configuring the ADT7463 as in Figure 12 allows the systems designer the following features: • Six VID Inputs (VID0 to VID5) for VRM10 Support • Two PWM Outputs for Fan Control of Up to Three Fans (The Front and Rear Chassis Fans Are Connected in Parallel) • Three TACH Fan Speed Measurement Inputs • • NOTE: See the AN−612 ADT7463 Configuration Application Note for more information and register settings for all possible configurations. ADT7463 FRONT CHASSIS FAN TACH2 PWM1 TACH1 REAR CHASSIS FAN PWM3 VID[0:4]/VID[0:5] TACH3 5(VRM9)/6(VRM10) D2+ D2− THERM D1+ AMBIENT TEMPERATURE PROCHOT D1− 3.3VSB 5V 12V/VID5 ADP316x VRM CONTROLLER VCOMP SDA SCL CURRENT VCORE SMBALERT GND Figure 12. Recommended Implementation http://onsemi.com 10 ADT7463 Serial Bus Interface Control of the ADT7463 is carried out using the serial system management bus (SMBus). The ADT7463 is connected to this bus as a slave device, under the control of a master controller. The ADT7463 has a 7−bit serial bus address. When the device is powered up with Pin 13 (PWM3/ ADDRESS ENABLE) high, the ADT7463 has a default SMBus address of 0101110 or 0x2E. The read/write bit must be added to get the 8−bit address. If more than one ADT7463 is used in a system, then each ADT7463 should be placed in address select mode by strapping Pin 13 low on power−up. The logic state of Pin 14 then determines the device’s SMBus address. The logic of these pins is sampled upon power−up. The device address is sampled and latched on the first valid SMBus transaction, more precisely on the low−to−high transition at the beginning of the 8th SCL pulse, when the serial bus address byte matches the selected slave address. The selected slave address is chosen using the address enable/address select pins. Any attempted changes in the address will have no effect after this. VCC ADT7463 ADDR_SEL PWM3/ 13 ADDR_EN ADDRESS = 0x2D Figure 15. SMBus Address = 0x2D (Pin 14 = 1) VCC ADT7463 ADDR_SEL Pin 14 State 0 Low (10 kW to GND) 0101100 (0x2C) 0 High (10 kW Pull−up) 0101101 (0x2D) 1 Don’t Care 0101110 (0x2E) (Default) DO NOT LEAVE ADDR_EN UNCONNECTED! CAN CAUSE UNPREDICTABLE ADDRESSES. CARE SHOULD BE TAKEN TO ENSURE THAT PIN 13 (PWM3/ADDR_EN) IS EITHER TIED HIGH OR LOW. LEAVING PIN 13 FLOATING COULD CAUSE THE ADT7463 TO POWERUP WITH AN UNEXPECTED ADDRESS. Address NOTE THAT IF THE ADT7463 IS PLACED INTO ADDRESS SELECT MODE, PINS 13 AND 14 CAN BE USED AS THE ALTERNATE FUNCTIONS (PWM3, TACH4/THERM) ONLY IF THE CORRECT CIRCUIT IS MUXED IN AT THE CORRECT TIME. Figure 16. Unpredictable SMBus Address if Pin 13 is Unconnected VCC The ability to make hardwired changes to the SMBus slave address allows the user to avoid conflicts with other devices sharing the same serial bus, for example, if more than one ADT7463 is used in a system. The serial bus protocol operates as follows: 1. The master initiates data transfer by establishing a START condition, defined as a high−to−low transition on the serial data line SDA while the serial clock line SCL remains high. This indicates that an address/data stream will follow. All slave peripherals connected to the serial bus respond to the START condition and shift in the next eight bits, consisting of a 7−bit address (MSB first) plus a R/W bit, which determines the direction of the data transfer, i.e., whether data will be written to or read from the slave device. The peripheral whose address corresponds to the transmitted address responds by pulling the data line low during the low period before the ninth ADT7463 ADDR_SEL 14 10 kW PWM3/ 13 ADDR_EN ADDRESS = 0x2E Figure 13. Default SMBus Address = 0x2E ADT7463 ADDR_SEL PWM3/ ADDR_EN 14 10 kW 14 PWM3/ 13 NC ADDR_EN Table 5. ADDRESS SELECT MODE Pin 13 State 10 kW 14 10 kW 13 ADDRESS = 0x2C Figure 14. SMBus Address = 0x2C (Pin 14 = 0) http://onsemi.com 11 ADT7463 before the 10th clock pulse, and then high during the 10th clock pulse to assert a STOP condition. clock pulse, known as the Acknowledge Bit. All other devices on the bus now remain idle while the selected device waits for data to be read from or written to it. If the R/W bit is a 0, then the master writes to the slave device. If the R/W bit is a 1, the master reads from the slave device. 2. Data is sent over the serial bus in sequences of nine clock pulses, eight bits of data followed by an Acknowledge Bit from the slave device. Transitions on the data line must occur during the low period of the clock signal and remain stable during the high period, as a low−to−high transition when the clock is high may be interpreted as a STOP signal. The number of data bytes that can be transmitted over the serial bus in a single READ or WRITE operation is limited only by what the master and slave devices can handle. 3. When all data bytes have been read or written, stop conditions are established. In WRITE mode, the master pulls the data line high during the tenth clock pulse to assert a STOP condition. In READ mode, the master device overrides the acknowledge bit by pulling the data line high during the low period before the ninth clock pulse. This is known as No Acknowledge. The master then takes the data line low during the low period Any number of bytes of data can be transferred over the serial bus in one operation, but it is not possible to mix read and write in one operation because the type of operation is determined at the beginning and cannot subsequently be changed without starting a new operation. In the case of the ADT7463, write operations contain either one or two bytes, and read operations contain one byte and perform the following functions. To write data to one of the device data registers or read data from it, the address pointer register must be set so that the correct data register is addressed, then data can be written into that register or read from it. The first byte of a write operation always contains an address that is stored in the address pointer register. If data is to be written to the device, then the write operation contains a second data byte that is written to the register selected by the address pointer register. This is illustrated in Figure 17. The device address is sent over the bus followed by R/W being set to 0. This is followed by two data bytes. The first data byte is the address of the internal data register to be written to, which is stored in the address pointer register. The second data byte is the data to be written to the internal data register. 1 9 1 9 SCL SDA 0 1 0 START BY MASTER 1 1 A0 A1 D6 D7 R/W ACK. BY ADT7463 FRAME 1 SERIAL BUS ADDRESS BYTE D4 D5 D2 D3 D1 D0 ACK. BY ADT7463 FRAME 2 ADDRESS POINTER REGISTER BYTE 1 9 SCL (CONTINUED) D7 SDA (CONTINUED) D4 D5 D6 D2 D3 D1 D0 ACK. BY ADT7463 FRAME 3 DATA BYTE STOP BY MASTER Figure 17. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register 1 9 9 1 SCL SDA 0 1 0 1 1 A1 START BY MASTER A0 D7 R/W D6 D5 D4 D3 D2 D1 FRAME 2 ADDRESS POINTER REGISTER BYTE FRAME 1 SERIAL BUS ADDRESS BYTE Figure 18. Writing to the Address Pointer Register Only http://onsemi.com 12 D0 ACK. BY ADT7463 ACK. BY ADT7463 STOP BY MASTER ADT7463 9 1 9 1 SCL SDA START BY MASTER 0 1 0 1 1 A1 A0 FRAME 1 SERIAL BUS ADDRESS BYTE R/W D7 D6 D5 ACK. BY ADT7463 D4 D2 D3 D1 D0 NO ACK. BY STOP BY MASTER MASTER FRAME 2 DATA BYTE FROM ADT7463 Figure 19. Reading Data from a Previously Selected Register Send Byte When reading data from a register, there are two possibilities: 1. If the ADT7463’s address pointer register value is unknown or not the desired value, it is first necessary to set it to the correct value before data can be read from the desired data register. This is done by performing a write to the ADT7463 as before, however, only the data byte is sent and this contains the register address. This is shown in Figure 18. A read operation is then performed consisting of the serial bus address, R/W bit set to 1, followed by the data byte read from the data register. This is shown in Figure 19. 2. If the address pointer register is already at the desired address, data can be read from the corresponding data register without first writing to the address pointer register, so Figure 18 can be omitted. In this operation, the master device sends a single command byte to a slave device as follows: 1. The master device asserts a start condition on SDA 2. The master sends the 7−bit slave address followed by the write bit (low) 3. The addressed slave device asserts ACK on SDA 4. The master sends a command code 5. The slave asserts ACK on SDA 6. The master asserts a stop condition on SDA and the transaction ends For the ADT7463, the send byte protocol is used to write a register address to RAM for a subsequent single byte read from the same address. This is illustrated in Figure 20. 1 2 3 SLAVE S W A ADDRESS 4 5 6 REGISTER ADDRESS A P Figure 20. Setting a Register Address for Subsequent Read NOTES: 1. It is possible to read a data byte from a data register without first writing to the address pointer register if the address pointer register is already at the correct value. However, it is not possible to write data to a register without writing to the address pointer register because the first data byte of a write is always written to the address pointer register. 2. In Figures 17 to 19, the serial bus address is shown as the default value 01011(A1)(A0), where A1 and A0 are set by the address select mode function previously defined. 3. In addition to supporting the Send Byte and Receive Byte protocols, the ADT7463 also supports the Read Byte protocol (see System Management Bus specifications Rev. 2.0 for more information). 4. If it is required to perform several read or write operations in succession, the master can send a repeat start condition instead of a stop condition to begin a new operation. If it is required to read data from the register immediately after setting up the address, the master can assert a repeat start condition immediately after the final ACK and carry out a single byte read without asserting an intermediate stop condition. Write Byte In this operation, the master device sends a command byte and one data byte to the slave device as follows: 1. The master device asserts a start condition on SDA 2. The master sends the 7−bit slave address followed by the write bit (low) 3. The addressed slave device asserts ACK on SDA 4. The master sends a command code 5. The slave asserts ACK on SDA 6. The master sends a data byte 7. The slave asserts ACK on SDA 8. The master asserts a stop condition on SDA to end the transaction ADT7463 Write Operations The SMBus specification defines several protocols for different types of read and write operations. The ones used in the ADT7463 are discussed below. The following abbreviations are used in the diagrams: S – START P – STOP R – READ W – WRITE A – ACKNOWLEDGE A – NO ACKNOWLEDGE This is illustrated in Figure 21. 1 2 3 SLAVE S ADDRESS W A 4 5 REGISTER ADDRESS A 6 7 8 DATA A P Figure 21. Single Byte Write to a Register The ADT7463 uses the following SMBus write protocols. http://onsemi.com 13 ADT7463 SMBus Timeout The ADT7463 includes an SMBus timeout feature. If there is no SMBus activity for 35 ms, the ADT7463 assumes that the bus is locked and releases the bus. This prevents the device from locking or holding the SMBus expecting data. Some SMBus controllers cannot handle the SMBus timeout feature, so it can be disabled. ADT7463 Read Operations The ADT7463 uses the following SMBus read protocols. Receive Byte This is useful when repeatedly reading a single register. The register address needs to have been set up previously. In this operation, the master device receives a single byte from a slave device as follows: 1. The master device asserts a start condition on SDA 2. The master sends the 7−bit slave address followed by the read bit (high) 3. The addressed slave device asserts ACK on SDA 4. The master receives a data byte 5. The master asserts NO ACK on SDA 6. The master asserts a stop condition on SDA and the transaction ends Table 6. CONFIGURATION REGISTER 1 (REG. 0X40) Bit 2 3 SLAVE S ADDRESS R A 4 5 6 DATA A P 0: SMBus Timeout Enabled (Default) TODIS 1: SMBus Timeout Disabled Voltage Measurement Inputs The ADT7463 has four external voltage measurement channels. It can also measure its own supply voltage, VCC. Pins 20 to 23 are dedicated to measuring 5 V, 12 V, and 2.5 V supplies and the processor core voltage VCCP (0 V to 3 V input). The VCC supply voltage measurement is carried out through the VCC pin (Pin 4). Setting Bit 7 of Configuration Register 1 (Reg. 0x40) allows a 5 V supply to power the ADT7463 and be measured without overranging the VCC measurement channel. The 2.5 V input can be used to monitor a chipset supply voltage in computer systems. In the ADT7463, the receive byte protocol is used to read a single byte of data from a register whose address has previously been set by a send byte or write byte operation. 1 Description TODIS Figure 22. Single Byte Read from a Register Analog−to−Digital Converter (ADC) All analog inputs are multiplexed into the on−chip, successive approximation, ADC. This has a resolution of 10 bits. The basic input range is 0 V to 2.25 V, but the inputs have built−in attenuators to allow measurement of 2.5 V, 3.3 V, 5 V, 12 V, and the processor core voltage VCCP without any external components. To allow for the tolerance of these supply voltages, the ADC produces an output of 3/4 full scale (decimal 768 or 300 hex) for the nominal input voltage and so has adequate headroom to cope with overvoltages. Alert Response Address Alert response address (ARA) is a feature of SMBus devices that allows an interrupting device to identify itself to the host when multiple devices exist on the same bus. The SMBALERT output can be used as an interrupt output or can be used as an SMBALERT. One or more outputs can be connected to a common SMBALERT line connected to the master. If a device’s SMBALERT line goes low, the following procedure occurs: 1. SMBALERT is pulled low 2. Master initiates a read operation and sends the alert response address (ARA = 0001 100). This is a general call address that must not be used as a specific device address 3. The device whose SMBALERT output is low responds to the alert response address, and the master reads its device address. The address of the device is now known and it can be interrogated in the usual way 4. If more than one device’s SMBALERT output is low, the one with the lowest device address will have priority in accordance with normal SMBus arbitration 5. Once the ADT7463 has responded to the alert response address, the master must read the status registers and the SMBALERT will only be cleared if the error condition has gone away Input Circuitry The internal structure for the analog inputs is shown in Figure 23. Each input circuit consists of an input protection diode, an attenuator, plus a capacitor to form a first−order, low−pass filter that gives the input immunity to high frequency noise. Table 7. VOLTAGE MEASUREMENT REGISTERS Register http://onsemi.com 14 Description Default 0x20 2.5 V Reading 0x00 0x21 VCCP Reading 0x00 0x22 VCC Reading 0x00 0x23 5 V Reading 0x00 0x24 12 V Reading 0x00 ADT7463 VID Code Monitoring The ADT7463 has five dedicated voltage ID (VID code) inputs. These are digital inputs that can be read back through the VID register (Reg. 0x43) to determine the processor voltage required/being used in the system. Five VID code inputs support VRM9.x solutions. In addition, Pin 21 (12 V input) can be reconfigured as a sixth VID input to satisfy future VRM requirements. Associated with each voltage measurement channel are high and low limit registers. Exceeding the programmed high or low limit causes the appropriate status bit to be set. Exceeding either limit can also generate SMBALERT interrupts. Table 8. VOLTAGE MEASUREMENT LIMITS REGISTERS Register Description Table 9. VID CODE REGISTER (REG. 0X43) Default 0x44 2.5 V Low Limit 0x00 Bit 0x45 2.5 V High Limit 0xFF VID0 Reflects Logic State of Pin 5 0x46 VCCP Low Limit 0x00 VID1 Reflects Logic State of Pin 6 0x47 VCCP High Limit 0xFF VID2 Reflects Logic State of Pin 7 0x48 VCC Low Limit 0x00 VID3 Reflects Logic State of Pin 8 0x49 VCC High Limit 0xFF VID4 Reflects Logic State of Pin 19 0x4A 5 V Low Limit 0x00 VID5 0x4B 5 V High Limit 0xFF 0x4C 12 V Low Limit 0x00 Reconfigurable 12 V Input. This bit reads 0 when Pin 21 is configured as the 12 V input. This bit reflects the logic state of Pin 21 when the pin is configured as VID5. 0x4D 12 V High Limit 0xFF VID Code Input Threshold Voltage The switching threshold for the VID code inputs is approximately 1 V. To enable future compatibility, it is possible to reduce the VID code input threshold to 0.6 V. Bit 6 (THLD) of VID register (Reg. 0x43) controls the VID input threshold voltage. 120 kW 12 VIN 20 kW 30 pF 93 kW Table 10. VID CODE REGISTER (REG. 0X43) 5 VIN 47 kW Bit 30 pF THLD 68 kW 3.3 VIN 71 kW 30 pF MUX 45 kW 30 pF 17.5 kW VCCP 52.5 kW Description 0: VID Switching Threshold = 1 V, VOL < 0.8 V, VIH > 1.7 V, VMAX = 3.3 V 1: VID Switching Threshold = 0.6 V, VOL < 0.4 V, VIH > 0.8 V, VMAX = 3.3 V Reconfiguring Pin 21 (+12V/VID5) as VID5 Input Pin 21 can be reconfigured as a sixth VID code input (VID5) for VRM10−compatible systems. Since the pin is configured as VID5, it is no longer possible to monitor a 12 V supply. Bit 7 of the VID register (Reg. 0x43) determines the function of Pin 21. System or BIOS software can read the state of Bit 7 to determine whether the system is designed to monitor 12 V or is monitoring a sixth VID input. 2.5 VIN 94 kW Description 35 pF Table 11. VID CODE REGISTER (REG. 0X43) Figure 23. Structure of Analog Inputs Bit Description VIDSEL 0: Pin 21 functions as a 12 V measurement input. Software can read this bit to determine that there are five VID inputs being monitored. Bit 5 of Register 0x43 (VID5) always reads back 0. Bit 0 of Status Register 2 (Reg. 0x42) reflects 12 V out−of−limit measurements. 1: Pin 21 functions as the sixth VID code input (VID5). Software can read this bit to determine that there are six VID inputs being monitored. Bit 5 of Register 0x43 reflects the logic state of Pin 21. Bit 0 of Status Register 2 (Reg. 0x42) reflects VID code changes. Table 12 shows the input ranges of the analog inputs and output codes of the 10−bit ADC. When the ADC is running, it samples and converts a voltage input in 711 ms and averages 16 conversions to reduce noise; a measurement on each input takes nominally 11.38 ms. http://onsemi.com 15 ADT7463 Table 12. 10−BIT A/D OUTPUT CODE VS. VIN Input Voltage A/D Output +12VIN +5VIN VCC (3.3VIN) (Note 1) +2.5VIN +VCCP Decimal Binary (10 Bits) 2.9970 1023 11111111 11 1. The VCC output codes listed assume that VCC is 3.3 V. If VCC input is reconfigured for 5 V operation (by setting Bit 7 of Configuration Register 1), then the VCC output codes are the same as for the +5VIN column. http://onsemi.com 16 ADT7463 VID Code Change Detect Function The ADT7463 has a VID code change detect function. When Pin 21 is configured as the VID5 input, VID code changes can be detected and reported back by the ADT7463. Bit 0 of Status Register 2 (Reg. 0x42) is the 12V/VC bit and denotes a VID change when set. The VID code change bit gets set when the logic states on the VID inputs are different than they were 11 ms previously. The change of VID code can be used to generate an SMBALERT interrupt. If an SMBALERT interrupt is not required, Bit 0 of Interrupt Mask Register 2 (Reg. 0x75), when set, prevents SMBALERTs from occurring on VID code changes. Table 14. CONFIGURATION REGISTER 2 (REG. 0X73) Bit 1: Averaging Off 1: Bypass Input Attenuators 1: Single−channel Convert Mode Table 15. TACH1 MINIMUM HIGH BYTE (REG. 0X55) Bit Description Selects ADC Channel for Single−channel Convert Mode Table 13. STATUS REGISTER (REG. 0X42) Bit 12V/VC Description Description 0: If Pin 21 is configured as VID5, then a Logic 0 denotes no change in VID code within last 11 ms. 1: If Pin 21 is configured as VID5, then a Logic 1 means that a change has occurred on the VID code inputs within the last 11 ms. An SMBALERT generates if this function is enabled. Value Channel Selected 000 2.5 V 001 VCCP 010 VCC 011 5V 100 12 V Temperature Measurement System Local Temperature Measurement The ADT7463 contains an on−chip band gap temperature sensor whose output is digitized by the on−chip 10−bit ADC. The 8−bit MSB temperature data is stored in the local temperature register (Address 26h). As both positive and negative temperatures can be measured, the temperature data is stored in twos complement format, as shown in Table 16. Theoretically, the temperature sensor and ADC can measure temperatures from –128°C to +127°C with a resolution of 0.25°C. However, this exceeds the operating temperature range of the device, so local temperature measurements outside this range are not possible. Additional ADC Functions for Voltage Measurement A number of other functions are available on the ADT7463 to offer the systems designer increased flexibility, including: Turn−off Averaging For each voltage measurement read from a value register, 16 readings have actually been made internally and the results averaged before being placed into the value register. There may be an instance where you would like to speed up conversions. Setting Bit 4 of Configuration Register 2 (Reg. 0x73) turns averaging off. This effectively gives a reading 16 times faster (711 ms), but the reading may be noisier. Remote Temperature Measurement The ADT7463 can measure the temperature of two remote diode sensors or diode−connected transistors connected to Pins 15 and 16, or 17 and 18. The forward voltage of a diode or diode−connected transistor operated at a constant current exhibits a negative temperature coefficient of about –2 mV/°C. Unfortunately, the absolute value of VBE varies from device to device and individual calibration is required to null this out, so the technique is unsuitable for mass production. The technique used in the ADT7463 is to measure the change in VBE when the device is operated at two different currents. This is given by Bypass Voltage Input Attenuators Setting Bit 5 of Configuration Register 2 (Reg 0x73) removes the attenuation circuitry from the 2.5 V, VCCP, VCC, 5 V, and 12 V inputs. This allows the user to directly connect external sensors or rescale the analog voltage measurement inputs for other applications. The input range of the ADC without the attenuators is 0 V to 2.25 V. Single−channel ADC Conversion Setting Bit 6 of Configuration Register 2 (Reg. 0x73) places the ADT7463 into single−channel ADC conversion mode. In this mode, the ADT7463 can be made to read a single voltage channel only. If the internal ADT7463 clock is used, the selected input is read every 711 ms. The appropriate ADC channel is selected by writing to Bits of the TACH1 Minimum High Byte Register (0x55). DV BE + KTńq ln(N) where: K is Boltzmann’s constant. q is the charge on the carrier. T is the absolute temperature in Kelvins. N is the ratio of the two currents. http://onsemi.com 17 (eq. 1) ADT7463 Figure 24 shows the input signal conditioning used to measure the output of a remote temperature sensor. This figure shows the external sensor as a substrate transistor, I N×I provided for temperature monitoring on some microprocessors. It could equally well be a discrete transistor, such as a 2N3904. VDD IBIAS CPU REMOTE SENSING TRANSISTOR THERMDA D+ THERMDC D− VOUT+ To ADC BIAS DIODE VOUT− LOW−PASS FILTER fC = 65 kHz Figure 24. Signal Conditioning for Remote Diode Temperature Sensors If a discrete transistor is used, the collector will not be grounded and should be linked to the base. If a PNP transistor is used, the base is connected to the D– input and the emitter to the D+ input. If an NPN transistor is used, the emitter is connected to the D– input and the base to the D+ input. Figures 25 and 26 show how to connect the ADT7463 to an NPN or PNP transistor for temperature measurement. To prevent ground noise from interfering with the measurement, the more negative terminal of the sensor is not referenced to ground but is biased above ground by an internal diode at the D– input. To measure DVBE, the sensor is switched between operating currents of I and N × I. The resulting waveform is passed through a 65 kHz low−pass filter to remove noise and to a chopper−stabilized amplifier that performs the functions of amplification and rectification of the waveform to produce a dc voltage proportional to DVBE. This voltage is measured by the ADC to give a temperature output in 10−bit, twos complement format. To further reduce the effects of noise, digital filtering is performed by averaging the results of 16 measurement cycles. A remote temperature measurement takes nominally 25.5 ms. The results of remote temperature measurements are stored in 10−bit, twos complement format, as illustrated in Table 16. The extra resolution for the temperature measurements is held in the Extended Resolution Register 2 (Reg. 0x77). This gives temperature readings with a resolution of 0.25°C. ADT7463 2N3906 PNP D− Figure 26. Measuring Temperature by Using a PNP Transistor Table 16. TEMPERATURE DATA FORMAT ADT7463 2N3904 NPN D+ D+ Temperature Digital Output (10−bit) (Note 1) −128°C 1000 0000 00 −125°C 1000 0011 00 −100°C 1001 1100 00 −75°C 1011 0101 00 −50°C 1100 1110 00 −25°C 1110 0111 00 −10°C 1111 0110 00 0°C 0000 0000 00 +10.25°C 0000 1010 01 +25.5°C 0001 1001 10 +50.75°C 0011 0010 11 +75°C 0100 1011 00 +100°C 0110 0100 00 +125°C 0111 1101 00 +127°C 0111 1111 00 1. Bold numbers denote 2 LSBs of measurement in the Extended Resolution Register 2 (0x77) with 0.25°C resolution. D− Figure 25. Measuring Temperature by Using an NPN Transistor http://onsemi.com 18 ADT7463 Table 17. TEMPERATURE MEASUREMENT REGISTERS Table 19. TEMPERATURE OFFSET REGISTERS Register Description Default Register Description Default 0x70 Remote 1 Temperature Offset 0x00 (0°C) 0x25 Remote 1 Temperature 0x80 0x71 Local Temperature Offset 0x00 (0°C) 0x26 Local Temperature 0x80 0x72 Remote 2 Temperature Offset 0x00 (0°C) 0x27 Remote 2 Temperature 0x80 0x77 Extended Resolution 2 0x00 Temperature Measurement Limit Registers Associated with each temperature measurement channel are high and low limit registers. Exceeding the programmed high or low limit causes the appropriate status bit to be set. Exceeding either limit can also generate SMBALERT interrupts. Table 18. EXTENDED RESOLUTION TEMPERATURE MEASUREMENT REGISTER BITS (REG. 0X77) Bit Mnemonic Description TDM2 Remote 2 Temperature LSBs LTMP Local Temperature LSBs TDM1 Remote 1 Temperature LSBs Table 20. TEMPERATURE MEASUREMENT LIMIT REGISTERS Reading Temperature from the ADT7463 It is important to note that temperature can be read from the ADT7463 as an 8−bit value (with 1°C resolution) or as a 10−bit value (with 0.25°C resolution). If only 1°C resolution is required, the temperature readings can be read back at any time and in no particular order. If the 10−bit measurement is required, this involves a 2−register read for each measurement. The extended resolution register (Reg. 0x77) should be read first. This causes all temperature reading registers to be frozen until all temperature reading registers have been read from. This prevents an MSB reading from being updated while its 2 LSBs are being read and vice versa. Register Description Default 0x4E Remote 1 Temperature Low Limit 0x81 0x4F Remote 1 Temperature High Limit 0x7F 0x50 Local Temperature Low Limit 0x81 0x51 Local Temperature High Limit 0x7F 0x52 Remote 2 Temperature Low Limit 0x81 0x53 Remote 2 Temperature High Limit 0x7F Overtemperature Events Overtemperature events on any of the temperature channels can be detected and dealt with automatically in automatic fan speed control mode. Registers 0x6A to 0x6C are the THERM limits. When a temperature exceeds its THERM limit, all fans run at 100% duty cycle. The fans stay running at 100% until the temperature drops below THERM – Hysteresis (this can be disabled by setting the boost bit in Configuration Register 3, Bit 2, Register 0x78). The hysteresis value for that THERM limit is the value programmed into Registers 0x6D, 0x6E (hysteresis registers). The default hysteresis value is 4°C. Nulling Out Temperature Errors As CPUs run faster, it is getting more difficult to avoid high frequency clocks when routing the D+, D– traces around a system board. Even when recommended layout guidelines are followed, there may still be temperature errors attributed to noise being coupled onto the D+/D– lines. High frequency noise generally has the effect of giving temperature measurements that are too high by a constant amount. The ADT7463 has temperature offset registers at Addresses 0x70, 0x72 for the Remote 1 and Remote 2 temperature channels. By doing a one−time calibration of the system, one can determine the offset caused by system board noise and null it out using the offset registers. The offset registers automatically add a twos complement 8−bit reading to every temperature measurement. The LSBs add 0.25°C offset to the temperature reading so the 8−bit register effectively allows temperature offsets of up to ±32°C with a resolution of 0.25°C. This ensures that the readings in the temperature measurement registers are as accurate as possible. THERM LIMIT TEMPERATURE FANS HYSTERESIS (°C) 100% Figure 27. THERM Limit Operation http://onsemi.com 19 ADT7463 Additional ADC Functions for Temperature Measurement A number of other functions are available on the ADT7463 to offer the systems designer increased flexibility. 8−bit Limits The following is a list of 8−bit limits on the ADT7463. Table 23. VOLTAGE LIMIT REGISTERS Register Turn−off Averaging For each temperature measurement read from a value register, 16 readings have actually been made internally and the results averaged before being placed into the value register. Sometimes it may be necessary to take a very fast measurement, e.g., of CPU temperature. Setting Bit 4 of Configuration Register 2 (Reg. 0x73) turns averaging off. This takes a reading every 13 ms. The measurement itself takes 4 ms. Description Default 0x44 2.5 V Low Limit 0x00 0x45 2.5 V High Limit 0xFF 0x46 VCCP Low Limit 0x00 0x47 VCCP High Limit 0xFF 0x48 VCC Low Limit 0x00 0xFF 0x49 VCC High Limit 0x4A 5 V Low Limit 0x00 0x4B 5 V High Limit 0xFF Single−channel ADC Conversions 0x4C 12 V Low Limit 0x00 Setting Bit 6 of Configuration Register 2 (Reg. 0x73) places the ADT7463 into single−channel ADC conversion mode. In this mode, the ADT7463 can be made to read a single temperature channel only. If the internal ADT7463 clock is used, the selected input is read every 1.4 ms. The appropriate ADC channel is selected by writing to Bits of TACH1 Minimum High Byte Register (0x55). 0x4D 12 V High Limit 0xFF Table 24. TEMPERATURE LIMIT REGISTERS Table 21. CONFIGURATION REGISTER 2 (REG. 0X73) Bit Description Register Description Default 0x4E Remote 1 Temperature Low Limit 0x81 0x4F Remote 1 Temperature High Limit 0x7F 0x6A Remote 1 THERM Limit 0x64 0x50 Local Temperature Low Limit 0x81 0x51 Local Temperature High Limit 0x7F 0x64 1: Averaging Off 0x6B Local THERM Limit 1: Single−channel Convert Mode 0x52 Remote 2 Temperature Low Limit 0x81 0x53 Remote 2 Temperature High Limit 0x7F 0x6C Remote 2 THERM Limit 0x64 Table 22. TACH1 MINIMUM HIGH BYTE (REG. 0X55) Bit Description Selects ADC Channel for Single−channel Convert Mode Table 25. THERM LIMIT REGISTERS Value Channel Selected 101 Remote 1 Temp 110 Local Temp 111 Remote 2 Temp Register 0x7A Description THERM Limit Default 0x00 16−bit Limits The fan TACH measurements are 16−bit results. The fan TACH limits are also 16 bits, consisting of a high byte and low byte. Since fans running under speed or stalled are normally the only conditions of interest, only high limits exist for fan TACHs. Since fan TACH period is actually being measured, exceeding the limit indicates a slow or stalled fan. Limits, Status Registers, and Interrupts Limit Values Associated with each measurement channel on the ADT7463 are high and low limits. These can form the basis of system status monitoring: a status bit can be set for any out−of−limit condition and detected by polling the device. Alternatively, SMBALERT interrupts can be generated to flag a processor or microcontroller of out−of−limit conditions. Table 26. FAN LIMIT REGISTERS Register Default 0x54 TACH1 Minimum Low Byte 0xFF 0x55 TACH1 Minimum High Byte 0xFF 0x56 TACH2 Minimum Low Byte 0xFF 0x57 TACH2 Minimum High Byte 0xFF 0x58 TACH3 Minimum Low Byte 0xFF 0x59 TACH3 Minimum High Byte 0xFF 0x5A TACH4 Minimum Low Byte 0xFF 0x5B TACH4 Minimum High Byte 0xFF http://onsemi.com 20 Description ADT7463 Out−of−Limit Comparisons Once all limits are programmed, the ADT7463 can be enabled for monitoring. The ADT7463 measures all parameters in round−robin format and sets the appropriate status bit for out−of−limit conditions. Comparisons are done differently depending on whether the measured value is being compared to a high or low limit. NO INT High Limit: > Comparison Performed Low Limit: < or = Comparison Performed HIGH LIMIT TEMP = HIGH LIMIT NO INT Figure 30. Temperature = High Limit: No INT INT LOW LIMIT TEMP > LOW LIMIT HIGH LIMIT Figure 28. Temperature > Low Limit: No INT TEMP > HIGH LIMIT INT Figure 31. Temperature > High Limit: INT Occurs Analog Monitoring Cycle Time The analog monitoring cycle begins when a 1 is written to the start bit (Bit 0) of Configuration Register 1 (Reg. 0x40). The ADC measures each analog input in turn and as each measurement is completed, the result is automatically stored in the appropriate value register. This round−robin monitoring cycle continues unless disabled by writing a 0 to Bit 0 of Configuration Register 1. Because the ADC is normally left to free−run in this manner, the time taken to monitor all the analog inputs is normally not of interest, since the most recently measured value of any input can be read out at any time. For applications where the monitoring cycle time is important, it is easily calculated. LOW LIMIT TEMP = LOW LIMIT Figure 29. Temperature = Low Limit: INT Occurs http://onsemi.com 21 ADT7463 • • • • The total number of channels measured is: Four Dedicated Supply Voltage Inputs 3.3 VSTBY or 5 V Supply (VCC Pin) Local Temperature Two Remote Temperatures Table 27. STATUS REGISTER 1 (REG. 0X41) As mentioned previously, the ADC performs round−robin conversions and takes 11.38 ms for each voltage measurement, 12 ms for a local temperature reading, and 25.5 ms for each remote temperature reading. The total monitoring cycle time for averaged voltage and temperature monitoring is therefore nominally (5 11.38) ) 12 (2 25.5) + 120 ms (eq. 2) Fan TACH measurements are made in parallel and are not synchronized with the analog measurements in any way. Status Registers The results of limit comparisons are stored in Status Registers 1 and 2. The status register bit for each channel reflects the status of the last measurement and limit comparison on that channel. If a measurement is within limits, the corresponding status register bit is cleared to 0. If the measurement is out−of−limits, the corresponding status register bit is set to 1. The state of the various measurement channels may be polled by reading the status registers over the serial bus. In Bit 7 (OOL) of Status Register 1 (Reg. 0x41), 1 means that an out−of−limit event has been flagged in Status Register 2. This means that a user need only read Status Register 2 when this bit is set. Alternatively, Pin 10 or Pin 22 can be configured as an SMBALERT output. This automatically notifies the system supervisor of an out−of−limit condition. Reading the status registers clears the appropriate status bit as long as the error condition that caused the interrupt has cleared. Status register bits are “sticky.” Whenever a status bit gets set, indicating an out−of−limit condition, it remains set even if the event that caused it has gone away (until read). The only way to clear the status bit is to read the status register after the event has gone away. Interrupt status mask registers (Reg. 0x74, 0x75) allow individual interrupt sources to be masked from causing an SMBALERT. However, if one of these masked interrupt sources goes out−of−limit, its associated status bit gets set in the interrupt status registers. Bit Mnemonic 7 OOL 1: denotes a bit in Status Register 2 is set and Status Register 2 should be read. Description 6 R2T 1: Remote 2 Temperature High or Low Limit has been exceeded. 5 LT 1: Local Temperature High or Low Limit has been exceeded. 4 R1T 1: Remote 1 Temperature High or Low Limit has been exceeded. 3 5V 1: 5 V High or Low Limit has been exceeded. 2 VCC 1: VCC High or Low Limit has been exceeded. 1 VCCP 1: VCCP High or Low Limit has been exceeded. 0 2.5V 1: 2.5 V High or Low Limit has been exceeded. F4P = 1, FAN 4 OR THERM TIMER IS OUT−OF−LIMIT Figure 33. Status Register 2 Table 28. STATUS REGISTER 2 (REG. 0X42) Bit Mnemonic 7 D2 1 indicates an open or short on D2+/D2− inputs. 6 D1 1 indicates an open or short on D2+/D2− inputs. 5 F4P 1 indicates that Fan 4 has dropped below minimum speed. Alternatively, indicates that THERM limit has been exceeded if the THERM function is used. 4 FAN3 1 indicates that Fan 3 has dropped below minimum speed. 3 FAN2 1 indicates that Fan 2 has dropped below minimum speed. 2 FAN1 1 indicates that Fan 1 has dropped below minimum speed. 1 OVT 1 indicates that a THERM overtemperature limit has been exceeded. 0 12V/VC OOL = 1 DENOTES A PARAMETER MONITORED THROUGH STATUS REG 2 IS OUT−OF−LIMIT Figure 32. Status Register 1 http://onsemi.com 22 Description 1 indicates that 12 V High or Low Limit has been exceeded. If the VID code change function is used, this bit indicates a change in VID code on the VID0 to VID5 inputs. ADT7463 SMBALERT Interrupt Behavior 4. Mask the interrupt source by setting the appropriate mask bit in the interrupt mask registers (Reg. 0x74, 0x75). 5. Take the appropriate action for a given interrupt source. 6. Exit the Interrupt Handler. 7. Periodically poll the status registers. If the interrupt status bit has cleared, reset the corresponding interrupt mask bit to 0. This causes the SMBALERT output and status bits to behave as shown in Figure 35. The ADT7463 can be polled for status, or an SMBALERT interrupt can be generated for out−of−limit conditions. It is important to note how the SMBALERT output and status bits behave when writing Interrupt Handler software. HIGH LIMIT TEMPERATURE “STICKY” STATUS BIT CLEARED ON READ (TEMP BELOW LIMIT) Masking Interrupt Sources Interrupt Mask Registers 1 and 2 are located at Addresses 0x74 and 0x75. These allow individual interrupt sources to be masked out to prevent SMBALERT interrupts. Note that masking an interrupt source only prevents the SMBALERT output from being asserted; the appropriate status bit gets set as normal. TEMP BACK IN LIMIT SMBALERT (STATUS BIT STAYS SET) Figure 34. SMBALERT and Status Bit Behavior Figure 34 shows how the SMBALERT output and “sticky” status bits behave. Once a limit is exceeded, the corresponding status bit gets set to 1. The status bit remains set until the error condition subsides and the status register gets read. The status bits are referred to as sticky since they remain set until read by software. This ensures that an out−of−limit event cannot be missed if software is polling the device periodically. Note that the SMBALERT output remains low for the entire duration that a reading is out−of−limit and until the status register has been read. This has implications on how software handles the interrupt. Table 29. INTERRUPT MASK REGISTER 1 (REG. 0X74) Handling SMBALERT Interrupts To prevent the system from being tied up servicing interrupts, it is recommend to handle the SMBALERT interrupt as follows: 1. Detect the SMBALERT assertion. 2. Enter the interrupt handler. 3. Read the status registers to identify the interrupt source. TEMPERATURE SMBALERT Mnemonic Description 7 OOL 1 masks SMBALERT for any alert condition flagged in Status Register 2. 6 R2T 1 masks SMBALERT for Remote 2 temperature. 5 LT 4 R1T 1 masks SMBALERT for Local Temperature. 1 masks SMBALERT for Remote 1 Temperature. 3 5V 1 masks SMBALERT for 5 V channel. 2 VCC 1 masks SMBALERT for VCC channel. 1 VCCP 1 masks SMBALERT for VCCP channel. 0 2.5V 1 masks SMBALERT for 2.5 V channel. Table 30. INTERRUPT MASK REGISTER 2 (REG. 0X75) HIGH LIMIT “STICKY” STATUS BIT Bit Bit Mnemonic Description 7 D2 1 masks SMBALERT for Diode 2 errors. 6 D1 1 masks SMBALERT for Diode 1 errors. 5 FAN4 1 masks SMBALERT for Fan 4 failure. If the TACH4 pin is being used as the THERM input, this bit masks SMBALERT for a THERM event. 4 FAN3 1 masks SMBALERT for Fan 3. 3 FAN2 1 masks SMBALERT for Fan 2. 2 FAN1 1 masks SMBALERT for Fan 1. 1 OVT 1 masks SMBALERT for overtemperature (exceeding THERM limits). 0 12V/VC CLEARED ON READ (TEMP BELOW LIMIT) TEMP BACK IN LIMIT (STATUS BIT STAYS SET) INTERRUPT MASK BIT SET INTERRUPT MASK BIT CLEARED (SMBALERT REARMED) Figure 35. How Masking the Interrupt Source Affects SMBALERT Output http://onsemi.com 23 1 masks SMBALERT for 12 V channel or for a VID code change, depending on the function used. ADT7463 Enabling the SMBALERT Interrupt Output mode is set to 0x00, then pulling the THERM low externally has no effect. See Figure 36 for more information. The SMBALERT interrupt function is disabled by default. Pin 10 or Pin 22 can be reconfigured as an SMBALERT output to signal out−of−limit conditions. TMIN Table 31. CONFIGURATION PIN 22 AS SMBALERT OUTPUT (REG. 0X78) Register Bit Setting Config Reg 3 ALERT = 1 THERM Table 32. CONFIGURATION PIN 22 AS SMBALERT OUTPUT (REG. 0X7D) Register Bit Setting Config Reg 4 AL2.5V = 1 THERM ASSERTED LOW AS AN INPUT. FANS DO NOT GO TO 100% SINCE TEMPERATURE IS BELOW TMIN. To Assign THERM Functionality to a Pin Pin 14 or Pin 20 can be configured as the THERM pin on the ADT7463. To enable the THERM functionality, users must first set the THERM enable bit. The TH5V bit then determines which pin the THERM functionality is enabled on (i.e., users cannot enable THERM on two pins at once). THERM ASSERTED LOW AS AN INPUT. FANS GO TO 100% SINCE TEMPERATURE IS ABOVE TMIN AND FANS ARE ALREADY RUNNING. Figure 36. Asserting THERM Low as an Input in Automatic Fan Speed Control Mode THERM Timer To configure Pin 20 as the THERM pin: 1. Set the TH5V bit (Bit 1) in the Configuration Register 4 (Address = 0x7D) = 1. 2. Set the THERM Enable Bit (Bit 1) in the Configuration Register 3 (Address = 0x78) = 1. The ADT7463 has an internal timer to measure THERM assertion time. For example, the THERM input may be connected to the PROCHOT output of a Pentium® 4 CPU and measure system performance. The THERM input may also be connected to the output of a trip point temperature sensor. The timer is started on the assertion of the ADT7463’s THERM input and stopped on the negation of the pin. The timer counts THERM times cumulatively, i.e., the timer resumes counting on the next THERM assertion. The THERM timer continues to accumulate THERM assertion times until the timer is read (it is cleared on read) or until it reaches full scale. If the counter reaches full scale, it stops at that reading until cleared. The 8−bit THERM timer register (Reg. 0x79) is designed such that Bit 0 gets set to 1 on the first THERM assertion. Once the cumulative THERM assertion time has exceeded 45.52 ms, Bit 1 of the THERM timer gets set and Bit 0 now becomes the LSB of the timer with a resolution of 22.76 ms. Figure 37 illustrates how the THERM timer behaves as the THERM input is asserted and negated. Bit 0 gets set on the first THERM assertion detected. This bit remains set until such time as the cumulative THERM assertions exceed 45.52 ms. At this time, Bit 1 of the THERM timer gets set, and Bit 0 is cleared. Bit 0 now reflects timer readings with a resolution of 22.76 ms. To configure Pin 14 as the THERM pin: 1. Set the TH5V bit (Bit 1) in the Configuration Register 4 (Address = 0x7D) = 0. 2. Set the THERM Enable Bit (Bit 1) in the Configuration Register 3 (Address = 0x78) = 1. THERM as an Input When configured as an input, the user can time assertions on the THERM pin. This can be useful for connecting to the PROCHOT output of a CPU to gauge system performance. See this data sheet for more information on timing THERM assertions and generating ALERTs based on THERM. The user can also setup the ADT7463 so when the THERM pin is driven low externally the fans run at 100%. The fans run at 100% for the duration of the THERM pin being pulled low. This is done by setting the BOOST bit (Bit 2) in Configuration Register 3 (Address = 0x78) to 1. This only works if the fan is already running, for example, in manual mode when the current duty cycle is above 0x00 or in automatic mode when the temperature is above TMIN. If the temperature is below TMIN or if the duty cycle in manual http://onsemi.com 24 ADT7463 When using the THERM timer, be aware of the following: • After a THERM timer read (Reg. 0x79): 1. The contents of the timer get cleared on read. 2. The F4P bit (Bit 5) of Status Register 2 needs to be cleared (assuming the THERM limit has been exceeded). • If the THERM timer is read during a THERM assertion, then the following will happen: 1. The contents of the timer are cleared. 2. Bit 0 of the THERM timer is set to 1 (since a THERM assertion is occurring). 3. The THERM timer increments from zero. 4. If the THERM limit (Reg. 0x7A) = 0x00, then the F4P bit gets set. THERM THERM TIMER (REG. 0x79) 0 0 0 0 0 0 0 1 7 6 5 4 3 2 1 0 THERM ASSERTED ≤22.76 ms THERM ACCUMULATE THERM LOW ASSERTION TIMES THERM TIMER (REG. 0x79) 0 0 0 0 0 0 1 0 7 6 5 4 3 2 1 0 Generating SMBALERT Interrupts from THERM Events THERM ASSERTED ≥45.52 ms The ADT7463 can generate SMBALERTs when a programmable THERM limit has been exceeded. This allows the systems designer to ignore brief, infrequent THERM assertions, while capturing longer THERM events. Register 0x7A is the THERM Limit Register. This 8−bit register allows a limit from 0 seconds (first THERM assertion) to 5.825 seconds to be set before an SMBALERT is generated. The THERM timer value is compared with the contents of the THERM limit register. If the THERM timer value exceeds the THERM limit value, then the F4P bit (Bit 5) of Status Register 2 gets set, and an SMBALERT is generated. Note that the F4P bit (Bit 5) of Mask Register 2 (Reg. 0x75) masks out SMBALERTs if this bit is set to 1, although the F4P bit of Interrupt Status Register 2 still gets set if the THERM limit is exceeded. THERM ACCUMULATE THERM LOW ASSERTION TIMES THERM TIMER (REG. 0x79) 0 0 0 0 0 1 0 1 7 6 5 4 3 2 1 0 THERM ASSERTED ≥113.8 ms (91.04 ms + 22.76 ms) Figure 37. Understanding the THERM Timer THERM LIMIT (REG. 0x7A) 2.914 s 1.457 s 728.32 ms 364.16 ms 182.08 ms 91.04 ms 45.52 ms 22.76 ms 2.914 s 1.457 s 728.32 ms 364.16 ms 182.08 ms 91.04 ms 45.52 ms 22.76 ms 0 1 2 3 4 5 6 7 THERM TIMER (REG. 0x79) THERM 7 6 5 4 3 2 1 0 THERM TIMER CLEARED ON READ COMPARATOR IN OUT LATCH F4P BIT (BIT 5) STATUS REGISTER 2 RESET CLEARED ON READ 1 = MASK F4P BIT (BIT 5) MASK REGISTER 2 (REG. 0x75) Figure 38. Functional Diagram of the ADT7463 THERM Monitoring Circuitry http://onsemi.com 25 SMBALERT ADT7463 Figure 38 is a Functional Block Diagram of the THERM timer, limit, and associated circuitry. Writing a value of 0x00 to the THERM limit register (Reg. 0x7A) causes SMBALERT to be generated on the first THERM assertion. A THERM limit value of 0x01 generates an SMBALERT once cumulative THERM assertions exceed 45.52 ms. then this is an indication of a serious degradation in system performance. Configuring the ADT7463 THERM Pin as an Output In addition to the ADT7463 being able to monitor THERM as an input, the ADT7463 can optionally drive THERM low as an output. The user can preprogram system critical thermal limits. If the temperature exceeds a thermal limit by 0.25°C, THERM asserts low. If the temperature is still above the thermal limit on the next monitoring cycle, THERM stays low. THERM remains asserted low until the temperature is equal to or below the thermal limit. Since the temperature for that channel is measured only every monitoring cycle, once THERM asserts it is guaranteed to remain low for at least one monitoring cycle. The THERM pin can be configured to assert low if the Remote 1, Local, or Remote 2 Temperature THERM limits get exceeded by 0.25°C. The THERM limit registers are at locations 0x6A, 0x6B, and 0x6C, respectively. Setting Bit 3 of Registers 0x5F, 0x60, and 0x61 enables the THERM output feature for the Remote 1, Local, and Remote 2 Temperature channels, respectively. Figure 39 shows how the THERM pin asserts low as an output in the event of a critical overtemperature. Configuring the Desired THERM Behavior 1. Configure the desired pin as the THERM input: Setting Bit 1 (THERM Enable) of Configuration Register 3 (Reg. 0x78) enables the THERM monitoring functionality. This is enabled on Pin 14 by default. Setting Bit 1 (TH5V) of Configuration Register 4 (Reg. 0x7D) enables THERM monitoring on Pin 20 (Bit 1 of Configuration Register 3 must also be set). Pin 14 can be used as TACH4. 2. Select the desired fan behavior for THERM events: Setting Bit 2 (BOOST bit) of Configuration Register 3 (Reg. 0x78) causes all fans to run at 100% duty cycle whenever THERM gets asserted. This allows fail−safe system cooling. If this bit = 0, the fans run at their current settings and are not affected by THERM events. 3. Select whether THERM events should generate SMBALERT interrupts: Bit 5 (F4P) of Mask Register 2 (Reg. 0x75), when set, masks out SMBALERTs when the THERM limit value gets exceeded. This bit should be cleared if SMBALERTs based on THERM events are required. 4. Select a suitable THERM limit value: This value determines whether an SMBALERT is generated on the first THERM assertion, or only if a cumulative THERM assertion time limit is exceeded. A value of 0x00 causes an SMBALERT to be generated on the first THERM assertion. 5. Select a THERM monitoring time: This is how often OS or BIOS level software checks the THERM timer. For example, BIOS could read the THERM timer once an hour to determine the cumulative THERM assertion time. If, for example, the total THERM assertion time is 182.08 ms in Hour 2, and >5.825 s in Hour 3, this can indicate that system performance is degrading significantly since THERM is asserting more frequently on an hourly basis. Alternatively, OS or BIOS level software can time−stamp when the system is powered on. If an SMBALERT is generated due to the THERM limit being exceeded, another time−stamp can be taken. The difference in time can be calculated for a fixed THERM limit time. For example, if it takes one week for a THERM limit of 2.914 s to be exceeded and the next time it takes only 1 hour, THERM LIMIT +0.255C THERM LIMIT TEMP THERM ADT7463 MONITORING CYCLE Figure 39. Asserting THERM as an Output, Based on Tripping THERM Limits Fan Drive Using PWM Control The ADT7463 uses pulse−width modulation (PWM) to control fan speed. This relies on varying the duty cycle (or on/off ratio) of a square wave applied to the fan to vary the fan speed. The external circuitry required to drive a fan using PWM control is extremely simple. A single NMOSFET is the only drive device required. The specifications of the MOSFET depend on the maximum current required by the fan being driven. Typical notebook fans draw a nominal 170 mA, and so SOT devices can be used where board space is a concern. In desktops, fans can typically draw 250 mA to 300 mA each. If you drive several fans in parallel from a single PWM output or drive larger server fans, the MOSFET needs to handle the higher current requirements. The only other stipulation is that the MOSFET should have a gate voltage drive, VGS < 3.3 V for direct interfacing to the PWM_OUT pin. VGS can be greater than 3.3 V as long as the http://onsemi.com 26 ADT7463 Driving Two Fans from PWM3 pull−up on the gate is tied to 5 V. The MOSFET should also have a low on resistance to ensure that there is not significant voltage drop across the FET. This reduces the voltage applied across the fan and therefore the maximum operating speed of the fan. Figure 40 shows how a 3−wire fan may be driven using PWM control. 12 V 10 kW 10 kW 12 V FAN TACH 4.7 kW ADT7463 12 V 1N4148 TACH/AIN Note that the ADT7463 has four TACH inputs available for fan speed measurement, but only three PWM drive outputs. If a fourth fan is being used in the system, it should be driven from the PWM3 output in parallel with the third fan. Figure 42 shows how to drive two fans in parallel using low cost NPN transistors. Figure 43 is the equivalent circuit using the NDT3055L MOSFET. Note that since the MOSFET can handle up to 3.5 A, it is simply a matter of connecting another fan directly in parallel with the first. Care should be taken in designing drive circuits with transistors and FETs to ensure that the PWM pins are not required to source current and that they sink less than the 8 mA maximum current specified on the data sheet. 3.3 V 12 V 10 kW 3.3 V ADT7463 3.3 V 1N4148 Q1 NDT3055L PWM TACH3 1 kW PWM3 Figure 40. Driving a 3−wire Fan Using an N−channel MOSFET 2.2 kW Figure 40 uses a 10 kW pull−up resistor for the TACH signal. This assumes that the TACH signal is open−collector from the fan. In all cases, the TACH signal from the fan must be kept below 5 V maximum to prevent damaging the ADT7463. If in doubt as to whether the fan used has an open−collector or totem pole TACH output, use one of the input signal conditioning circuits shown in the Fan Speed Measurement section of the data sheet. Figure 41 shows a fan drive circuit using an NPN transistor such as a general−purpose MMBT2222. While these devices are inexpensive, they tend to have much lower current handling capabilities and higher on resistance than MOSFETs. When choosing a transistor, care should be taken to ensure that it meets the fan’s current requirements. Ensure that the base resistor is chosen such that the transistor is saturated when the fan is powered on. 12 V TACH 4.7 kW ADT7463 12 V FAN Q3 MMBT2222 Figure 42. Interfacing Two Fans in Parallel to the PWM3 Output Using Low Cost NPN Transistors 3.3 V 10 kW TYP 3.3 V ADT7463 TACH3 10 kW TYP TACH 3.3 V 10 kW TYP PWM3 +V +V 5V or 12 V FAN 1N4148 TACH4 TACH 5V or 12 V FAN Q1 NDT3055L 3.3 V Figure 43. Interfacing Two Fans in Parallel to the PWM3 Output Using a Single N−channel MOSFET 470 W PWM Q2 MMBT2222 10 W 12 V 10 kW Q1 MMBT3904 10 W 1N4148 TACH/AIN 10 kW TACH4 Q1 MMBT2222 Driving Up to Three Fans from PWM2 TACH measurements for fans are synchronized to particular PWM channels, e.g., TACH1 is synchronized to PWM1. TACH3 and TACH4 are both synchronized to Figure 41. Driving a 3−wire Fan Using an NPN Transistor http://onsemi.com 27 ADT7463 PWM3 so PWM3 can drive 2 fans. Alternatively, PWM2 can be programmed to synchronize TACH2, TACH3, and TACH4 to the PWM2 output. This allows PWM2 to drive two or three fans. In this case, the drive circuitry looks the same as shown in Figures 42 and 43. The SYNC bit in Register 0x62 enables this function. n: 250 mV @: –258mV Table 33. SYNC: ENHANCE ACOUSTICS REGISTER 1 (REG. 0X62) Bit Mnemonic SYNC Description 1 Synchronizes TACH2, TACH3, and TACH4 to PWM2. Driving 2−wire Fans Figure 44 shows how a 2−wire fan may be connected to the ADT7463. This circuit allows the speed of a 2−wire fan to be measured, even though the fan has no dedicated TACH signal. A series resistor, RSENSE, in the fan circuit converts the fan commutation pulses into a voltage. This is ac−coupled into the ADT7463 through the 0.01 mF capacitor. On−chip signal conditioning allows accurate monitoring of fan speed. The value of RSENSE chosen depends upon the programmed input threshold and the current drawn by the fan. For fans drawing approximately 200 mA, a 2 W RSENSE value is suitable when the threshold is programmed as 40 mV. For fans that draw more current, such as larger desktop or server fans, RSENSE may be reduced for the same programmed threshold. The smaller the threshold programmed the better, since more voltage is developed across the fan and the fan spins faster. Figure 45 shows a typical plot of the sensing waveform at the TACH/AIN pin. The most important thing is that the voltage spikes (either negative going or positive going) are more than 40 mV in amplitude. This allows fan speed to be reliably determined. 10 kW TYPICAL PWM –2.00mV R1 1N4148 3.3 V or 5.0 V R2 R5 C1 TACH/AIN R4 PWM Q1 MMBT2222 FOR 3−WIRE FANS: POPULATE R1, R2, R3 R4 = 0 W C1 = UNPOPULATED FOR 2−WIRE FANS: POPULATE R4, C1 R1, R2, R3 UNPOPULATED Figure 46. Planning for 2−wire or 3−wire Fans on a PCB Q1 NDT3055L 0.01 mF TACH/AIN A CH1 -1.00000ms 12 V or 5.0 V 1N4148 3.3 V T Laying Out 2−wire and 3−wire Fans Figure 46 shows how to lay out a common circuit arrangement for 2−wire and 3−wire fans. Some components are not populated, depending on whether a 2−wire or 3−wire fan is being used. R3 5V or 12 V FAN M 4.00ms Figure 45. Fan Speed Sensing Waveform at TACH/AIN Pin +V ADT7463 CH2 5.00mV CH4 50.0mV CH1 100mV CH3 50.0mV TACH Inputs RSENSE 2W TYPICAL Pins 9, 11, 12, and 14 are open−drain TACH inputs intended for fan speed measurement. Signal conditioning in the ADT7463 accommodates the slow rise and fall times typical of fan tachometer outputs. Figure 44. Driving a 2−wire Fan http://onsemi.com 28 ADT7463 The maximum input signal range is 0 V to 5 V, even where VCC is less than 5 V. In the event that these inputs are supplied from fan outputs that exceed 0 V to 5 V, either resistive attenuation of the fan signal or diode clamping must be included to keep inputs within an acceptable range. Figures 47 to 50 show circuits for most common fan TACH outputs. If the fan TACH output has a resistive pull−up to VCC, it can be connected directly to the fan input, as shown in Figure 47. 5.0 V or12 V R1 10 kW PULL−UP TYP < 1 kW PULL−UP 4.7 kW TYP TACH 12 V VCC FAN SPEED COUNTER If the fan output has a resistive pull−up to 12 V (or other voltage greater than 5 V) then the fan output can be clamped with a Zener diode, as shown in Figure 48. The Zener diode voltage should be chosen so that it is greater than VIH of the TACH input but less than 5 V, allowing for the voltage tolerance of the Zener. A value of between 3 V and 5 V is suitable. ZD1* FAN SPEED COUNTER R2* Figure 50. Fan with Strong TACH. Pullup to > VCC or Totem−Pole Output, Attenuated with R1/R2 Fan Speed Measurement The fan counter does not count the fan TACH output pulses directly because the fan speed may be less than 1,000 RPM and it would take several seconds to accumulate a reasonably large and accurate count. Instead, the period of the fan revolution is measured by gating an on−chip 90 kHz oscillator into the input of a 16−bit counter for N periods of the fan TACH output (Figure 51), so the accumulated count is actually proportional to the fan tachometer period and inversely proportional to the fan speed. ADT7463 TACH ADT7463 TACH *SEE TEXT VCC TACH OUTPUT TACH OUTPUT R1* Figure 47. Fan with TACH Pull−up to VCC PULL−UP 4.7 kW TYP ZD1* ZENER FAN SPEED COUNTER Figure 49. Fan with Strong TACH. Pull−up to > VCC or Totem−Pole Output, Clamped with Zener and Resistor < 1 kW 12 V TACH *CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 × VCC ADT7463 TACH OUTPUT TACH OUTPUT ADT7463 OR TOTEM−POLE VCC 12 V VCC FAN FAN SPEED COUNTER *CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 × VCC CLOCK Figure 48. Fan with TACH Pull−up to Voltage > 5.0 V, e.g., 12 V, Clamped with Zener Diode PWM If the fan has a strong pull−up (less than 1 kW) to 12 V or a totempole output, then a series resistor can be added to limit the Zener current, as shown in Figure 49. Alternatively, a resistive attenuator may be used, as shown in Figure 50. R1 and R2 should be chosen such that: 2 V t V PULLUP TACH 1 2 3 4 R2ń(R PULLUP ) R1 ) R2) t 5 V (eq. 3) Figure 51. Fan Speed Measurement The fan inputs have an input resistance of nominally 160 kW to ground, so this should be taken into account when calculating resistor values. With a pull−up voltage of 12 V and pull−up resistor less than 1 kW, suitable values for R1 and R2 would be 100 kW and 47 kW. This gives a high input voltage of 3.83 V. N, the number of pulses counted, is determined by the settings of Register 0x7B (fan pulses per revolution register). This register contains two bits for each fan, allowing one, two (default), three, or four TACH pulses to be counted. http://onsemi.com 29 ADT7463 If any of the fans are not being driven by a PWM channel but are powered directly from 5 V or 12 V, its associated dc bit in Configuration Register 3 should be set. This allows TACH readings to be taken on a continuous basis for fans connected directly to a dc source. The fan tachometer readings are 16−bit values consisting of a 2−byte read from the ADT7463. Table 34. FAN SPEED MEASUREMENT REGISTERS Register Description Default 0x28 TACH1 Low Byte 0x00 0x29 TACH1 High Byte 0x00 0x2A TACH2 Low Byte 0x00 0x2B TACH2 High Byte 0x00 0x2C TACH3 Low Byte 0x00 0x2D TACH3 High Byte 0x00 0x2E TACH4 Low Byte 0x00 0x2F TACH4 High Byte 0x00 Calculating Fan Speed Assuming a fan with a two pulses/revolution (and two pulses/revolution being measured), fan speed is calculated by: Fan Speed (RPM) + (90, 000 where: Fan TACH Reading = 16−bit Fan Tachometer Reading Example: Reading Fan Speed from the ADT7463 TACH1 HIGH Byte (Reg. 0x29) + 0x17 If fan speeds are being measured, this involves a 2−register read for each measurement. The low byte should be read first. This causes the high byte to be frozen until both high and low byte registers have been read from. This prevents erroneous TACH readings. The fan tachometer reading registers report back the number of 11.11 ms period clocks (90 kHz oscillator) gated to the fan speed counter, from the rising edge of the first fan TACH pulse to the rising edge of the third fan TACH pulse (assuming two pulses per revolution are being counted). Since the device is essentially measuring the fan TACH period, the higher the count value the slower the fan is actually running. A 16−bit fan tachometer reading of 0xFFFF indicates either that the fan has stalled or is running very slowly (< 100 RPM). TACH1 LOW Byte (Reg. 0x28) + 0xFF What is Fan 1 speed in RPM? Fan 1 TACH Reading + 0x17FF + 6143 Decimal RPM + (f 60)ń6143 Fan Speed + 879 RPM Fan Pulses per Revolution Different fan models can output either 1, 2, 3, or 4 Tach pulses per revolution. Once the number of fan Tach pulses has been determined, it is programmed into the fan pulses per revolution register (Reg. 0x7B) for each fan. Alternatively, this register can be used to determine the number or pulses/revolution output by a given fan. By plotting fan speed measurements at 100% speed with different pulses/revolution setting, the smoothest graph with the lowest ripple determines the correct pulses/revolution value. HighLimit :u ComparisonPerformed Table 36. FAN PULSES PER REVOLUTION REGISTER (REG. 0X7B) Table 35. FAN TACH LIMIT REGISTERS Description 60)ńFan 1 TACH Reading RPM + (90, 000 Since the actual fan TACH period is being measured, exceeding a fan TACH limit by 1 sets the appropriate status bit and can be used to generate an SMBALERT. The fan TACH limit registers are 16−bit values consisting of two bytes. Register 60)ńFan TACH Reading Default Bit Mnemonic Description 0x54 TACH1 Minimum Low Byte 0xFF FAN1 Default 2 Pulses per Revolution 0x55 TACH1 Minimum High Byte 0xFF FAN2 Default 2 Pulses per Revolution 0x56 TACH2 Minimum Low Byte 0xFF FAN3 Default 2 Pulses per Revolution 0x57 TACH2 Minimum High Byte 0xFF FAN4 Default 2 Pulses per Revolution 0x58 TACH3 Minimum Low Byte 0xFF 0x59 TACH3 Minimum High Byte 0xFF 0x5A TACH4 Minimum Low Byte 0xFF 0x5B TACH4 Minimum High Byte 0xFF Table 37. FAN PULSES PER REVOLUTION REGISTER BIT VALUES Value Fan Speed Measurement Rate The fan TACH readings are normally updated once every second. The FAST bit (Bit 3) of Configuration Register 3 (Reg. 0x78), when set, updates the fan TACH readings every 250 ms. http://onsemi.com 30 Description 00 1 Pulse per Revolution 01 2 Pulses per Revolution 10 3 Pulses per Revolution 11 4 Pulses per Revolution ADT7463 2−wire Fan Speed Measurements Table 40. PWM1 TO PWM3 CONFIGURATION (REG. 0X5C TO 0X5E) The ADT7463 is capable of measuring the speed of 2−wire fans, i.e., fans without TACH outputs. To do this, the fan must be interfaced as shown in the Fan Drive Circuitry section of the data sheet. In this case, the TACH inputs need to be reprogrammed as analog inputs, AIN. Bit Mnemonic Description SPIN These bits control the start−up timeout for PWM1, PWM2, PWM3: 000 = No Start−up Timeout 001 = 100 ms 010 = 250 ms (Default) 011 = 400 ms 100 = 667 ms 101 = 1 s 110 = 2 s 111 = 4 s Table 38. CONFIGURATION REGISTER 2 (REG. 0X73) Bit Mnemonic Description 3 AIN4 1 indicates that Pin 14 is reconfigured to measure the speed of a 2−wire fan using an external sensing resistor and coupling capacitor. 2 AIN3 1 indicates that Pin 9 is reconfigured to measure the speed of a 2−wire fan using an external sensing resistor and coupling capacitor. 1 AIN2 1 indicates that Pin 12 is reconfigured to measure the speed of a 2−wire fan using an external sensing resistor and coupling capacitor. 0 AIN1 1 indicates that Pin 11 is reconfigured to measure the speed of a 2−wire fan using an external sensing resistor and coupling capacitor. Disabling Fan Start−up Timeout Although fan start−up makes fan spin−ups much quieter than fixed−time spin−ups, the option exists to use fixed spin−up times. Bit 5 (FSPDIS) = 1 in Configuration Register 1 (Reg. 0x40) disables the spin−up for two TACH pulses. Instead, the fan spins up for the fixed time as selected in Registers 0x5C to 0x5E. PWM Logic State The PWM outputs can be programmed high for 100% duty cycle (non inverted) or low for 100% duty cycle (inverted). AIN Switching Threshold Having configured the TACH inputs as AIN inputs for 2−wire measurements, users can select the sensing threshold for the AIN signal. Table 41. PWM1 TO PWM3 CONFIGURATION (REG. 0X5C TO 0X5E) Table 39. CONFIGURATION REGISTER 4 (REG. 0X7D) Bit Mnemonic AINL Bit Mnemonic INV Description These two bits define the input threshold for 2−wire fan speed measurements. 00 = ±20 mV 01 = ±40 mV 10 = ±80 mV 11 = ±130 mV Description 0 = Logic High for 100% PWM Duty Cycle 1 = Logic Low for 100% PWM Duty Cycle PWM Drive Frequency The PWM drive frequency can be adjusted for the application. Registers 0x5F to 0x61 configure the PWM frequency for PWM1 to PWM3, respectively. Fan Spin−up Table 42. PWM1 TO PWM3 FREQUENCY REGISTERS (REG. 0X5F TO 0X61) The ADT7463 has a unique fan spin−up function. It spins the fan at 100% PWM duty cycle until two TACH pulses are detected on the TACH input. Once two pulses are detected, the PWM duty cycle goes to the expected running value, e.g., 33%. The advantage of this is that fans have different spin−up characteristics and takes different times to overcome inertia. The ADT7463 just runs the fans fast enough to overcome inertia and are quieter on spin−up than fans programmed to spin−up for a given spin−up time. Fan Start−up Timeout Bit Mnemonic FREQ Description 000 = 11.0 Hz 001 = 14.7 Hz 010 = 22.1 Hz 011 = 29.4 Hz 100 = 35.3 Hz (Default) 101 = 44.1 Hz 110 = 58.8 Hz 111 = 88.2 Hz Fan Speed Control To prevent false interrupts being generated as a fan spins up (since it is below running speed), the ADT7463 includes a fan start−up timeout function. This is the time limit allowed for two TACH pulses to be detected on spin−up. For example, if 2−second fan start−up timeout is chosen and no TACH pulses occur within 2 seconds of the start of spin−up, a fan fault is detected and flagged in the interrupt status registers. The ADT7463 can control fan speed using two different modes. The first is automatic fan speed control mode. In this mode, fan speed is automatically varied with temperature and without CPU intervention, once initial parameters are set up. The advantage of this is in the case of the system hanging, the user is guaranteed that the system is protected from overheating. The automatic fan speed control http://onsemi.com 31 ADT7463 incorporates a feature called dynamic TMIN calibration. This feature reduces the design effort required to program the automatic fan speed control loop. For more information and how to program the automatic fan speed control loop and dynamic TMIN calibration, see the AN−613 Programming the Automatic Fan Speed Control Loop Application Note. The second fan speed control method is manual fan speed control which is described in the next paragraph. Table 44. PWM DUTY CYCLE REGISTERS Register The ADT7463 allows the duty cycle of any PWM output to be manually adjusted. This can be useful if users wish to change fan speed in software or want to adjust PWM duty cycle output for test purposes. Bits of Registers 0x5C to 0x5E (PWM Configuration) control the behavior of each PWM output. BHVR 0x30 PWM1 Duty Cycle 0xFF (100%) 0x31 PWM2 Duty Cycle 0xFF (100%) 0x32 PWM3 Duty Cycle 0xFF (100%) Operating from 3.3 V Standby The ADT7463 has been specifically designed to operate from a 3.3 V STBY supply. In computers that support S3 and S5 states, the core voltage of the processor is lowered in these states. If using the dynamic TMIN mode, lowering the core voltage of the processor would change the CPU temperature and change the dynamics of the system under dynamic TMIN control. Likewise, when monitoring THERM, the THERM timer should be disabled during these states. Table 43. PWM1 TO PWM3 CONFIGURATION (REG. 0X5C TO 0X5E) Mnemonic Default By reading the PWMx current duty cycle registers, users can keep track of the current duty cycle on each PWM output, even when the fans are running in automatic fan speed control mode or acoustic enhancement mode. Manual Fan Speed Control Bit Description Description 111 = Manual Mode Once under manual control, each PWM output may be manually updated by writing to Registers 0x30 to 0x32 (PWMx current duty cycle registers). Dynamic TMIN Control Register (Reg. 0x36) VCCPLO = 1 When the power is supplied from 3.3 V STBY and the VCCP voltage drops below the VCCP low limit, the following occurs: • Status Bit 1 (VCCP) in Status Register 1 Gets Set • SMBALERT Gets Generated If Enabled • THERM Monitoring Is Disabled. The THERM Timer Should Hold Its Value Prior To the S3 or S5 State • Dynamic TMIN Control Is Disabled. This Prevents TMIN from Being Adjusted Due To an S3 or S5 State • The ADT7463 Is Prevented from Entering the Shutdown State VARY PWM DUTY CYCLE WITH 8−BIT RESOLUTION Once the core voltage, VCCP, goes above the VCCP low limit, everything gets re−enabled and the system resumes normal operation. Note that since other voltages can drop or be turned off during a low power state, these voltage channels set status bits or generate SMBALERTs. It is still necessary to mask out these channels prior to entering a low power state using the interrupt mask registers. When exiting the low power state, the mask bits can be cleared. This prevents the device from generating unwanted SMBALERTs during the low power state. Figure 52. Control PWM Duty Cycle Manually with a Resolution of 0.39% Programming the PWM Current Duty Cycle Registers The PWM current duty cycle registers are 8−bit registers that allow the PWM duty cycle for each output to be set anywhere from 0% to 100% in steps of 0.39%. The value to be programmed into the PWMMIN register is given by Value(Decimal) + PWM MINń0.39 XOR Tree Test Mode The ADT7463 includes an XOR Tree Test Mode. This mode is useful for in−circuit test equipment at board−level testing. By applying stimulus to the pins included in the XOR Tree, it is possible to detect opens or shorts on the system board. Figure 53 shows the signals that are exercised in the XOR Tree Test Mode. Example 1: For a PWM duty cycle of 50%, Value(Decimal) + 50ń0.39 + 128 Decimal Value + 128 Decimal or 0x80 Example 2: For a PWM duty cycle of 33%, Value(Decimal) + 33ń0.39 + 85 Decimal Value + 85 Decimal or 0x54 http://onsemi.com 32 ADT7463 VID0 VID1 The XOR Tree Test is invoked by setting Bit 0 (XEN) of the XOR Tree Test Enable Register (Reg. 0x6F). VID2 Power−on Default The ADT7463 does not monitor temperature and fan speed by default on power−up. Monitoring of temperature and fan speed is enabled by setting the Start Bit in Configuration Register 1 (Bit 0, Address 0x40) to 1. The fans run at full speed on power−up. This is because the BHVR bits (Bits ) in the PWMx configuration registers are set to 100 (fans run full speed) by default. VID3 VID4 TACH1 TACH2 TACH3 TACH4 PWM2 PWM3 PWM1/XTO Figure 53. XOR Tree Test Table 45. ADT7463 REGISTERS Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default 2.5 V Reading 9 8 7 6 5 4 3 2 0x00 VCCP Reading 9 8 7 6 5 4 3 2 0x00 R VCC Reading 9 8 7 6 5 4 3 2 0x00 0x23 R 5 V Reading 9 8 7 6 5 4 3 2 0x00 0x24 R 12 V Reading 9 8 7 6 5 4 3 2 0x00 0x25 R Remote 1 Temperature 9 8 7 6 5 4 3 2 0x80 0x26 R Local Temperature 9 8 7 6 5 4 3 2 0x80 0x27 R Remote 2 Temperature 9 8 7 6 5 4 3 2 0x80 0x28 R TACH1 Low Byte 7 6 5 4 3 2 1 0 0x00 Addr R/W 0x20 R 0x21 R 0x22 Description Lockable 0x29 R TACH1 High Byte 15 14 13 12 11 10 9 8 0x00 0x2A R TACH2 Low Byte 7 6 5 4 3 2 1 0 0x00 0x2B R TACH2 High Byte 15 14 13 12 11 10 9 8 0x00 0x2C R TACH3 Low Byte 7 6 5 4 3 2 1 0 0x00 0x2D R TACH3 High Byte 15 14 13 12 11 10 9 8 0x00 0x2E R TACH4 Low Byte 7 6 5 4 3 2 1 0 0x00 0x2F R TACH4 High Byte 15 14 13 12 11 10 9 8 0x00 0x30 R/W PWM1 Current Duty Cycle 7 6 5 4 3 2 1 0 0xFF 0x31 R/W PWM2 Current Duty Cycle 7 6 5 4 3 2 1 0 0xFF 0x32 R/W PWM3 Current Duty Cycle 7 6 5 4 3 2 1 0 0xFF 0x33 R/W Remote 1 Operating Point 7 6 5 4 3 2 1 0 0x64 YES 0x34 R/W Local Temp Operating Point 7 6 5 4 3 2 1 0 0x64 YES 0x35 R/W Remote 2 Operating Point 7 6 5 4 3 2 1 0 0x64 YES http://onsemi.com 33 ADT7463 Table 45. ADT7463 REGISTERS Addr R/W Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable 0x36 R/W Dynamic TMIN Control Reg 1 R2T LT R1T PHTR2 PHTL PHTR1 VCCPLO CYR2 0x00 YES 0x37 R/W Dynamic TMIN Control Reg 2 CYR2 CYR2 CYL CYL CYL CYR1 CYR1 CYR1 0x00 YES 0x3 R Device ID Register 7 6 5 4 3 2 1 0 0x27 0x3E R Company ID Number 7 6 5 4 3 2 1 0 0x41 0x3F R Revision Number VER VER VER VER STP STP STP STP 0x62 or 0x6A 0x40 R/W Configuration Register 1 VCC TODIS FSPDIS V×I FSPD RDY LOCK STRT 0x00 0x41 R Interrupt Status Register 1 OOL R2T LT R1T 5V VCC VCCP 2.5V 0x00 0x42 R Interrupt Status Register 2 D2 D1 F4P FAN3 FAN2 FAN1 OVT 12V/VC 0x00 0x43 R/W VID Register VIDSEL THLD VID5 VID4 VID3 VID2 VID1 VID0 0xFF 0x44 R/W 2.5 V Low Limit 7 6 5 4 3 2 1 0 0x00 0x45 R/W 2.5 V High Limit 7 6 5 4 3 2 1 0 0xFF 0x46 R/W VCCP Low Limit 7 6 5 4 3 2 1 0 0x00 0x47 R/W VCCP High Limit 7 6 5 4 3 2 1 0 0xFF 0x48 R/W VCC Low Limit 7 6 5 4 3 2 1 0 0x00 0x49 R/W VCC High Limit 7 6 5 4 3 2 1 0 0xFF 0x4A R/W 5 V Low Limit 7 6 5 4 3 2 1 0 0x00 0xFF YES 0x4B R/W 5 V High Limit 7 6 5 4 3 2 1 0 0x4C R/W 12 V Low Limit 7 6 5 4 3 2 1 0 0x00 0x4D R/W 12 V High Limit 7 6 5 4 3 2 1 0 0xFF 0x4E R/W Remote 1 Temp Low Limit 7 6 5 4 3 2 1 0 0x81 0x4F R/W Remote 1 Temp High Limit 7 6 5 4 3 2 1 0 0x7F 0x50 R/W Local Temp Low Limit 7 6 5 4 3 2 1 0 0x81 0x51 R/W Local Temp High Limit 7 6 5 4 3 2 1 0 0x7F 0x52 R/W Remote 2 Temp Low Limit 7 6 5 4 3 2 1 0 0x81 0x53 R/W Remote 2 Temp High Limit 7 6 5 4 3 2 1 0 0x7F 0x54 R/W TACH1 Minimum Low Byte 7 6 5 4 3 2 1 0 0xFF 0x55 R/W TACH1 Minimum High Byte 15 14 13 12 11 10 9 8 0xFF 0x56 R/W TACH2 Minimum Low Byte 7 6 5 4 3 2 1 0 0xFF 0x57 R/W TACH2 Minimum High Byte 15 14 13 12 11 10 9 8 0xFF 0x58 R/W TACH3 Minimum Low Byte 7 6 5 4 3 2 1 0 0xFF 0x59 R/W TACH3 Minimum High Byte 15 14 13 12 11 10 9 8 0xFF 0x5A R/W TACH4 Minimum Low Byte 7 6 5 4 3 2 1 0 0xFF 0x5B R/W TACH4 Minimum High Byte 15 14 13 12 11 10 9 8 0xFF 0x5C R/W PWM1 Configuration Register BHVR BHVR BHVR INV SLOW SPIN SPIN SPIN 0x62 YES 0x5D R/W PWM2 Configuration Register BHVR BHVR BHVR INV SLOW SPIN SPIN SPIN 0x62 YES 0x5E R/W PWM3 Configuration Register BHVR BHVR BHVR INV SLOW SPIN SPIN SPIN 0x62 YES http://onsemi.com 34 ADT7463 Table 45. ADT7463 REGISTERS Addr R/W Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable 0x5F R/W Remote 1 TRANGE/PWM1 Freq. RANGE RANGE RANGE RANGE THRM FREQ FREQ FREQ 0xC4 YES 0x60 R/W Local Temp TRANGE/PWM2 Freq. RANGE RANGE RANGE RANGE THRM FREQ FREQ FREQ 0xC4 YES 0x61 R/W Remote 2 TRANGE/PWM3 Freq. RANGE RANGE RANGE RANGE THRM FREQ FREQ FREQ 0xC4 YES 0x62 R/W Enhance Acoustics Register 1 MIN3 MIN2 MIN1 SYNC EN1 ACOU ACOU ACOU 0x00 YES 0x63 R/W Enhance Acoustics Register 2 EN2 ACOU2 ACOU2 ACOU2 EN3 ACOU3 ACOU3 ACOU3 0x00 YES 0x64 R/W PWM1 Min Duty Cycle 7 6 5 4 3 2 1 0 0x80 YES 0x65 R/W PWM2 Min Duty Cycle 7 6 5 4 3 2 1 0 0x80 YES 0x66 R/W PWM3 Min Duty Cycle 7 6 5 4 3 2 1 0 0x80 YES 0x67 R/W Remote 1 Temp TMIN 7 6 5 4 3 2 1 0 0x5A YES 0x68 R/W Local Temp TMIN 7 6 5 4 3 2 1 0 0x5A YES 0x69 R/W Remote 2 Temp TMIN 7 6 5 4 3 2 1 0 0x5A YES 0x6A R/W Remote 1 THERM Limit 7 6 5 4 3 2 1 0 0x64 YES 0x6B R/W Local THERM Limit 7 6 5 4 3 2 1 0 0x64 YES 0x6C R/W Remote 2 THERM Limit 7 6 5 4 3 2 1 0 0x64 YES 0x6D R/W Remote 1 Local Temp Hysteresis HYSR1 HYSR1 HYSR1 HYSR1 HYSL HYSL HYSL HYSL 0x44 YES 0x6E R/W Remote 2 Temp Hysteresis HYSR2 HYSR2 HYSR2 HYSR2 RES RES RES RES 0x40 YES 0x6F R/W XOR Tree Test Enable RES RES RES RES RES RES RES XEN 0x00 YES 0x70 R/W Remote 1 Temperature Offset 7 6 5 4 3 2 1 0 0x00 YES 0x71 R/W Local Temperature Offset 7 6 5 4 3 2 1 0 0x00 YES 0x72 R/W Remote 2 Temperature Offset 7 6 5 4 3 2 1 0 0x00 YES 0x73 R/W Configuration Register 2 SHDN CONV ATTN AVG AIN4 AIN3 AIN2 AIN1 0x00 YES 0x74 R/W Interrupt Mask 1 Reg. OOL R2T LT R1T 5V VCC VCCP 2.5V 0x00 0x75 R/W Interrupt Mask 2 Reg. D2 D1 F4P FAN3 FAN2 FAN1 OVT 12V/VC 0x00 0x76 R/W Extended Resolution Register 1 5V 5V VCC VCC VCCP VCCP 2.5V 2.5V 0x00 0x77 R/W Extended Resolution Register 2 TDM2 TDM2 LTMP LTMP TDM1 TDM1 12V 12V 0x00 0x78 R/W Configuration Register 3 DC4 DC3 DC2 DC1 FAST BOOST THERM ENABLE ALERT 0x00 0x79 R THERM Status Reg. TMR TMR TMR TMR TMR TMR TMR ASRT/ TMR0 0x00 0x7A R/W THERM Limit Reg. LIMT LIMT LIMT LIMT LIMT LIMT LIMT LIMT 0x00 0x7B R/W Fan Pulses per Revolution FAN4 FAN4 FAN3 FAN3 FAN2 FAN2 FAN1 FAN1 0x55 0x7D R/W Configuration Register 4 RES RES RES RES AINL AINL TH5V AL2.5V 0x00 YES 0x7E R Test Register 1 DO NOT WRITE TO THESE REGISTERS 0x00 YES 0x7F R Test Register 2 DO NOT WRITE TO THESE REGISTERS 0x00 YES http://onsemi.com 35 YES ADT7463 Table 46. VOLTAGE READING REGISTERS (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W 0x20 Read−only 2.5 V Reading (8 MSBs of Reading) Description 0x21 Read−only VCCP Reading: Holds Processor Core Voltage Measurement (8 MSBs of Reading) 0x22 Read−only VCC Reading: Measures VCC through the VCC Pin (8 MSBs of Reading) 0x23 Read−only 5 V Reading (8 MSBs of Reading) 0x24 Read−only 12 V Reading (8 MSBs of Reading) 1. If the extended resolution bits of these readings are also being read, the extended resolution registers (Reg. 0x76, 0x77) should be read first. Once the extended resolution registers get read, the associated MSB reading registers get frozen until read. Both the extended resolution registers and the MSB registers get frozen. Table 47. TEMPERATURE READING REGISTERS (POWER−ON DEFAULT = 0X80) (Note 1) Register Address R/W 0x25 Read−only Remote 1 Temperature Reading (8 MSBs of reading) (Note 2) Description 0x26 Read−only Local Temperature Reading (8 MSBs of Reading) 0x27 Read−only Remote 2 Temperature Reading (8 MSBs of reading) (Note 2) 1. These voltage readings are in twos complement format. 2. Note that a reading of 0x80 in a temperature reading register indicates a diode fault (open or short) on that channel. If the extended resolution bits of these readings are also being read, the extended resolution registers (Reg. 0x76, 0x77) should be read first. Once the extended resolution registers are read, the associated MSB reading registers are frozen until read. Both the extended resolution registers and the MSB registers are frozen. Table 48. FAN TACHOMETER READING REGISTERS (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W Description 0x28 Read−only TACH1 Low Byte 0x29 Read−only TACH1 High Byte 0x2A Read−only TACH2 Low Byte 0x2B Read−only TACH2 High Byte 0x2C Read−only TACH3 Low Byte 0x2D Read−only TACH3 High Byte 0x2E Read−only TACH4 Low Byte 0x2F Read−only TACH4 High Byte 1. These registers count the number of 11.11 ms periods (based on an internal 90 kHz clock) that occur between a number of consecutive fan TACH pulses (default = 2). The number of TACH pulses used to count can be changed using the fan pulses per revolution register (Reg. 0x7B). This allows the fan speed to be accurately measured. Since a valid fan tachometer reading requires that two bytes are read, the low byte MUST be read first. Both the low and high bytes are then frozen until read. At power−on, these registers contain 0x0000 until such time as the first valid fan TACH measurement is read in to these registers. This prevents false interrupts from occurring while the fans are spinning up. A count of 0xFFFF indicates that a fan is: • Stalled or blocked (object jamming the fan). • Failed (internal circuitry destroyed). • Not populated. (The ADT7463 expects to see a fan connected to each TACH. If a fan is not connected to that TACH, its TACH minimum high and low byte should be set to 0xFFFF.) • Alternate function, for example, TACH4 reconfigured as a THERM pin. • 2−wire Instead of 3−wire Fan Table 49. CURRENT PWM DUTY CYCLE REGISTERS (POWER−ON DEFAULT = 0XFF) (Note 1) Register Address R/W 0x30 R/W PWM1 Current Duty Cycle (0% to 100% Duty Cycle = 0x00 to 0xFF). Description 0x31 R/W PWM2 Current Duty Cycle (0% to 100% Duty Cycle = 0x00 to 0xFF). 0x32 R/W PWM3 Current Duty Cycle (0% to 100% Duty Cycle = 0x00 to 0xFF). 1. These registers reflect the PWM duty cycle driving each fan at any given time. When in automatic fan speed control mode, the ADT7463 reports the PWM duty cycles back through these registers. The PWM duty cycle values vary according to temperature in automatic fan speed control mode. During fan startup, these registers report back 0x00. In software mode, the PWM duty cycle outputs can be set to any duty cycle value by writing to these registers. http://onsemi.com 36 ADT7463 Table 50. OPERATING POINT REGISTERS (POWER−ON DEFAULT = 0X64) (Note 1) Register Address R/W Description 0x33 R/W Remote 1 Operating Point Register (Default = 100°C) 0x34 R/W Local Temp Operating Point Register (Default = 100°C) 0x35 R/W Remote 2 Operating Point Register (Default = 100°C) 1. These registers become read−only when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers will fail. These registers set the target operating point for each temperature channel when the dynamic TMIN control feature is enabled. The fans being controlled are adjusted to maintain temperature about an operating point. Table 51. REGISTER 0X36 − DYNAMIC TMIN CONTROL REGISTER 1 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W Description CYR2 R/W MSB of 3−bit Remote 2 Cycle Value. The other two bits of the code reside in Dynamic TMIN Control Register 2 (Reg. 0x37). These three bits define the delay time between making subsequent TMIN adjustments in the control loop, in terms of number of monitoring cycles. The system has associated thermal time constants that need to be found to optimize the response of fans and the control loop. VCCPLO R/W VCCPLO = 1. When the power is supplied from 3.3 V STANDBY and the core voltage (VCCP) drops below its VCCP low limit value (Reg. 0x46), the following occurs: • Status Bit 1 in Status Register 1 gets set • SMBALERT gets generated if enabled • PROCHOT monitoring is disabled • Dynamic TMIN control is disabled • The device is prevented from entering shutdown • Everything re−enabled once VCCP increases above VCCP low limit PHTR1 R/W PHTR1 = 1 copies the Remote 1 current temperature to the Remote 1 Operating Point Register if THERM is asserted. The operating point contains the temperature at which THERM is asserted. This allows the system to run as quietly as possible without affecting system performance. PHTR1 = 0 ignores any THERM assertions on the THERM pin. The Remote 1 Operating Point Tegister reflects its programmed value. PHTL R/W PHTL = 1 copies the local channel’s current temperature to the Local Operating Point Register if THERM is asserted. The operating point contains the temperature at which THERM is asserted. This allows the system to run as quietly as possible without affecting system performance. PHTL = 0 ignores any THERM assertions on the THERM pin. The Local Temperature Operating Point Register reflects its programmed value. PHTR2 R/W PHTR2 = 1 copies the Remote 2 current temperature to the Remote 2 Operating Point Register if THERM is asserted. The operating point contains the temperature at which THERM is asserted. This allows the system to run as quietly as possible without system performance being affected. PHTR2 = 0 ignores any THERM assertions on the THERM pin. The Remote 2 Operating Point Register reflects its programmed value. R1T R/W R1T = 1 enables dynamic TMIN control on the Remote 1 Temperature channel. The chosen TMIN value is dynamically adjusted based on the current temperature, operating point, and high and low limits for this zone. R1T = 0 disables dynamic TMIN control. The TMIN value chosen is not adjusted, and the channel behaves as described in the Automatic Fan Control section. LT R/W LT = 1 enables dynamic TMIN control on the Local Temperature channel. The chosen TMIN value is dynamically adjusted based on the current temperature, operating point, and high and low limits for this zone. LT = 0 disables dynamic TMIN control. The TMIN value chosen is not adjusted, and the channel behaves as described in the Automatic Fan Control section. R2T R/W R2T = 1 enables dynamic TMIN control on the Remote 2 Temperature channel. The chosen TMIN value is dynamically adjusted based on the current temperature, operating point, and high and low limits for this zone. R2T = 0 disables dynamic TMIN control. The TMIN value chosen is not adjusted, and the channel behaves as described in the Automatic Fan Control section. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. http://onsemi.com 37 ADT7463 Table 52. REGISTER 0X37 − DYNAMIC TMIN CONTROL REGISTER 2 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W Description CYR1 R/W 3−bit Remote 1 Cycle Value. These three bits define the delay time between making subsequent TMIN adjustments in the control loop for the Remote 1 channel, in terms of number of monitoring cycles. The system has associated thermal time constants that need to be found to optimize the response of fans and the control loop. Bits 000 001 010 011 100 101 110 111 CYL R/W CYR2 R/W Increase Cycle 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) 1024 Cycles (128 s) 3−bit Local Temperature Cycle Value. These three bits define the delay time between making subsequent TMIN adjustments in the control loop for local temperature channel, in terms of number of monitoring cycles. The system has associated thermal time constants that need to be found to optimize the response of fans and the control loop. Bits 000 001 010 011 100 101 110 111 Decrease Cycle 4 Cycles (0.5 s) 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) Decrease Cycle 4 Cycles (0.5 s) 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) Increase Cycle 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) 1024 Cycles (128 s) 2 LSBs of 3−bit Remote 2 Cycle Value. The MSB of the 3−bit code resides in Dynamic TMIN Control Register 1 (Reg. 0x36). These three bits define the delay time between making subsequent TMIN adjustments in the control loop for the Remote 2 channel, in terms of number of monitoring cycles. The system has associated thermal time constants that need to be found to optimize the response of fans and the control loop. Bits Decrease Cycle Increase Cycle 000 001 010 011 100 101 110 111 4 Cycles (0.5 s) 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) 8 Cycles (1 s) 16 Cycles (2 s) 32 Cycles (4 s) 64 Cycles (8 s) 128 Cycles (16 s) 256 Cycles (32 s) 512 Cycles (64 s) 1024 Cycles (128 s) 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. http://onsemi.com 38 ADT7463 Table 53. REGISTER 0X40 − CONFIGURATION REGISTER 1 (POWER−ON DEFAULT = 0X00) Bit Name R/W Description STRT R/W Logic 1 enables monitoring and PWM control outputs based on the limit settings programmed. Logic 0 disables monitoring and PWM control based on the default power−up limit settings. Note that the limit values programmed are preserved even if a Logic 0 is written to this bit and the default settings are enabled. This bit becomes read−only and cannot be changed once Bit 1 (LOCK bit) has been written. All limit registers should be programmed by BIOS before setting this bit to 1. (Lockable.) LOCK Write Once Logic 1 locks all limit values to their current settings. Once this bit is set, all lockable registers become read−only and cannot be modified until the ADT7463 is powered down and powered up again. This prevents rogue programs such as viruses from modifying critical system limit settings. (Lockable.) RDY Read−only This bit is set to 1 by the ADT7463 to indicate that the device is fully powered−up and ready to begin systems monitoring. FSPD R/W When set to 1, all fans run at full speed. Power−on default = 0. (This bit cannot be locked.) V×I R/W BIOS should set this bit to a 1 when the ADT7463 is configured to measure current from an ADI ADOPTt VRM controller and measure the CPU’s core voltage. This allows monitoring software to display CPU watts usage. (Lockable.) FSPDIS R/W Logic 1 disables fan spin−up for two TACH pulses. Instead, the PWM outputs go high for the entire fan spin−up timeout selected. TODIS R/W When set to 1, the SMBus timeout feature is disabled. This allows the ADT7463 to be used with SMBus controllers that cannot handle SMBus timeouts. (Lockable.) VCC R/W When set to 1, the ADT7463 rescales its VCC pin to measure a 5.0 V supply. When set to 0, the ADT7463 measures VCC as a 3.3 V supply. (Lockable.) Table 54. REGISTER 0X41 − INTERRUPT STATUS REGISTER 1 (POWER−ON DEFAULT = 0X00) Bit Name R/W Description 2.5V Read−only A 1 indicates that the 2.5 V high or low limit has been exceeded. This bit is cleared on a read of the status register only if the error condition has subsided. VCCP Read−only A 1 indicates the VCCP high or low limit has been exceeded. This bit gets cleared on a read of the status register only if the error condition has subsided. VCC Read−only A 1 indicates that the VCC high or low limit has been exceeded. This bit is cleared on a read of the status register only if the error condition has subsided. 5V Read−only A 1 indicates the 5 V high or low limit has been exceeded. This bit gets cleared on a read of the status register only if the error condition has subsided. R1T Read−only A 1 indicates that the Remote 1 Low or High temperature limit has been exceeded. This bit is cleared on a read of the status register only if the error condition has subsided. LT Read−only A 1 indicates the Local Low or High temperature limit has been exceeded. This bit is cleared on a read of the Status Register only if the error condition has subsided. R2T Read−only A 1 indicates that the Remote 2 Low or High temperature limit has been exceeded. This bit is cleared on a read of the status register only if the error condition has subsided. OOL Read−only A 1 indicates that an out−of−limit event has been latched in Status Register 2. This bit is a logical OR of all status bits in Status Register 2. Software can test this bit in isolation to determine whether any of the voltage, temperature, or fan speed readings represented by Status Register 2 are out−of−limit. This saves the need to read Status Register 2 every interrupt or polling cycle. http://onsemi.com 39 ADT7463 Table 55. REGISTER 0X42 − INTERRUPT STATUS REGISTER 2 (POWER−ON DEFAULT = 0X00) Bit Name R/W Description 12V/VC Read−only A one indicates the 12 V high or low limit has been exceeded. This bit gets cleared on a read of the status register only if the error condition has subsided. If Pin 21 is configured as VID5, this bit is the VID change bit. This bit gets set when the levels on VID0 to VID5 are different than they were 11 ms previously. This can be used to generate an SMBALERT whenever the VID code changes. OVT Read−only A 1 indicates that one of the THERM overtemperature limits has been exceeded. This bit is cleared on a read of the status register when the temperature drops below THERM − THYST. FAN1 Read−only A 1 indicates that Fan 1 has dropped below minimum speed or has stalled. This bit is NOT set when the PWM1 output is off. FAN2 Read−only A 1 indicates that Fan 2 has dropped below minimum speed or has stalled. This bit is NOT set when the PWM2 output is off. FAN3 Read−only A 1 indicates that Fan 3 has dropped below minimum speed or has stalled. This bit is NOT set when the PWM3 output is off. F4P Read−only A 1 indicates that Fan 4 has dropped below minimum speed or has stalled. This bit is NOT set when the PWM3 output is off. If Pin 14 or Pin 20 is configured as the THERM timer input for THERM monitoring, this bit is set when the THERM assertion time exceeds the limit programmed in the THERM Limit Register (Reg. 0x7A). D1 Read−only A 1 indicates either an open or short circuit on the Thermal Diode 1 inputs. D2 Read−only A 1 indicates either an open or short circuit on the Thermal Diode 2 inputs. Table 56. REGISTER 0X43 − VID REGISTER (POWER−ON DEFAULT = 0X00) Bit Name R/W VID[4:0] Read−only The VID[4:0] inputs from the CPU to indicate the expected processor core voltage. On power−up, these bits reflect the state of the VID pins even if monitoring is not enabled. Description VID5 Read−only Reads VID5 from the CPU when Bit 7 = 1. If Bit 7 = 0, then the VID5 bit always reads back 0 (power−on default). THLD R/W This selects the input switching threshold for the VID inputs. THLD = 0 selects a threshold of 1 V (VOL < 0.8 V, VIH > 1.7 V). THLD = 1 lowers the switching threshold to 0.6 V (VOL < 0.4 V, VIH > 0.8 V). VIDSEL R/W VIDSEL = 0 configures Pin 21 as the 12 V measurement input (default). VIDSEL = 1 configures Pin 21 as the VID5 input. This also allows VID code changes to be detected. Table 57. VOLTAGE LIMIT REGISTERS (Note 1) Register Address R/W 0x44 R/W 2.5 V Low Limit 0x00 0x45 R/W 2.5 V High Limit 0xFF 0x46 R/W VCCP Low Limit 0x00 0x47 R/W VCCP High Limit 0xFF 0x48 R/W VCC Low Limit 0x00 0x49 R/W VCC High Limit 0xFF 0x4A R/W 5 V Low Limit 0x00 0x4B R/W 5 V High Limit 0xFF 0x4C R/W 12 V Low Limit 0x00 0x4D R/W 12 V High Limit 0xFF Description (Note 2) Power−On Default 1. Setting the Configuration Register 1 Lock bit has no effect on these registers. 2. High limits: an interrupt is generated when a value exceeds its high limit (> comparison); Low limits: an interrupt is generated when a value is equal to or below its low limit (≤ comparison). http://onsemi.com 40 ADT7463 Table 58. TEMPERATURE LIMIT REGISTERS (Note 1) Register Address R/W 0x4E R/W Remote 1 Temperature Low Limit 0x81 0x4F R/W Remote 1 Temperature High Limit 0x7F 0x50 R/W Local Temperature Low Limit 0x81 0x51 R/W Local Temperature High Limit 0x7F 0x52 R/W Remote 2 Temperature Low Limit 0x81 0x53 R/W Remote 2 Temperature High Limit 0x7F Description (Note 2) Power−On Default 1. Exceeding any of these temperature limits by 1°C causes the appropriate status bit to be set in the Interrupt Status Register. Setting the Configuration Register 1 Lock bit has no effect on these registers. 2. High limits: an interrupt is generated when a value exceeds its high limit (> comparison); Low limits: an interrupt is generated when a value is equal to or below its low limit (≤ comparison). Table 59. FAN TACHOMETER LIMIT REGISTERS (POWER−ON DEFAULT = 0XFF) (Note 1) Register Address R/W Description 0x54 R/W TACH1 Minimum Low Byte 0x55 R/W TACH1 Minimum High Byte 0x56 R/W TACH2 Minimum Low Byte 0x57 R/W TACH2 Minimum High Byte 0x58 R/W TACH3 Minimum Low Byte 0x59 R/W TACH3 Minimum High Byte 0x5A R/W TACH4 Minimum Low Byte 0x5B R/W TACH4 Minimum High Byte 1. Exceeding any of the TACH limit registers by 1 indicates that the fan is running too slowly or has stalled. The appropriate status bit is set in Interrupt Status Register 2 to indicate the fan failure. Setting the Configuration Register 1 Lock bit has no effect on these registers. Table 60. PWM CONFIGURATION REGISTERS (POWER−ON DEFAULT = 0X62) (Note 1) Register Address R/W Description 0x5C R/W PWM1 Configuration 0x5D R/W PWM2 Configuration 0x5E R/W PWM3 Configuration 1. These registers become read−only when the Configuration Register 1 Lock bit is set to 1. Any subsequent attempts to write to these registers fail. http://onsemi.com 41 ADT7463 Table 61. PWM CONFIGURATION REGISTER BITS Bit Name R/W SPIN R/W These bits control the start−up timeout for PWMx. The PWM output stays high until two valid TACH rising edges are seen from the fan. If there is not a valid TACH signal during the fan TACH measurement directly after the fan start−up timeout period, the TACH measurement reads 0xFFFF and Status Register 2 reflects the fan fault. If the TACH Minimum High and Low Byte contains 0xFFFF or 0x0000, the Status Register 2 Bit is not set, even if the fan has not started. 000 = No Start−up Timeout 001 = 100 ms 010 = 250 ms (Default) 011 = 400 ms 100 = 667 ms 101 = 1 s 110 = 2 s 111 = 4 s Description SLOW R/W SLOW = 1 makes the ramp rates for acoustic enhancement four times longer. INV R/W This bit inverts the PWM output. The default is 0, which corresponds to a logic high output for 100% duty cycle. Setting this bit to 1 inverts the PWM output, so 100% duty cycle corresponds to a logic low output. BHVR R/W These bits assign each fan to a particular temperature sensor for localized cooling. 000 = Remote 1 Temperature controls PWMx (Automatic Fan Control Mode). 001 = Local Temperature controls PWMx (Automatic Fan Control Mode). 010 = Remote 2 Temperature controls PWMx (Automatic Fan Control Mode). 011 = PWMx runs full speed (Default). 100 = PWMx is disabled. 101 = Fastest speed calculated by Local and Remote 2 Temperature Control PWMx. 110 = Fastest speed calculated by all three Temperature Channels Control PWMx. 111 = Manual Mode. PWM duty cycle registers (Reg. 0x30–0x32) become writable. Table 62. TEMP TRANGE/PWM FREQUENCY REGISTERS (POWER−ON DEFAULT = 0XC4) (Note 1) Register Address R/W Description 0x5F R/W Remote 1 TRANGE/PWM1 Frequency 0x60 R/W Local Temp TRANGE/PWM2 Frequency 0x61 R/W Remote 2 TRANGE/PWM3 Frequency 1. These registers become read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to the is register have no effect. Table 63. TEMP TRANGE/PWM FREQUENCY REGISTER BITS Bit Name R/W Description FREQ R/W These bits control the PWMx frequency. 000 = 11.0 Hz 001 = 14.7 Hz 010 = 22.1 Hz 011 = 29.4 Hz 100 = 35.3 Hz (Default) 101 = 44.1 Hz 110 = 58.8 Hz 111 = 88.2 Hz THRM R/W THRM = 1 causes the THERM pin (Pin 14 or Pin 20) to assert low as an output when this temperature channel’s THERM limit is exceeded by 0.25°C. The THERM pin remains asserted until the temperature is equal to or below the THERM limit. The minimum time that THERM asserts for is one monitoring cycle. This allows clock modulation of devices that incorporate this feature. THRM = 0 makes the THERM pin act as an input only, for example, for Pentium® 4 PROCHOT monitoring, when Pin 14 or Pin 20 is configured as THERM. RANGE R/W These bits determine the PWM duty cycle vs. temperature slope for automatic fan control. 0000 = 2°C 0001 = 2.5°C 0010 = 3.33°C 0011 = 4°C 0100 = 5°C 0101 = 6.67°C 0110 = 8°C 0111 = 10°C 1000 = 13.33°C 1001 = 16°C 1010 = 20°C 1011 = 26.67°C 1100 = 32°C (Default) 1101 = 40°C 1110 = 53.33°C 1111 = 80°C http://onsemi.com 42 ADT7463 Table 64. REGISTER 0X62 − ENHANCED ACOUSTICS REGISTER 1 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W Description ACOU R/W These bits select the ramp rate applied to the PWM1 output. Instead of PWM1 jumping instantaneously to its newly calculated speed, PWM1 ramps gracefully at the rate determined by these bits. This feature enhances the acoustics of the fan being driven by the PWM1 output. Time Slot Increase 000 = 1 001 = 2 010 = 3 011 = 4 100 = 8 101 = 12 110 = 24 111 = 48 Time for 33% to 100% 35 sec 17.6 sec 11.8 sec 7 sec 4.4 sec 3 sec 1.6 sec 0.8 sec EN1 R/W When this bit is 1, acoustic enhancement is enabled on PWM1 output. SYNC R/W SYNC = 1 synchronizes fan speed measurements on TACH2, TACH3, and TACH4 to PWM3. This allows up to three fans to be driven from PWM3 output and their speeds to be measured. SYNC = 0, only TACH3 and TACH4 are synchronized to PWM3 output. MIN1 R/W When the ADT7463 is in automatic fan control mode, this bit defines whether PWM1 is off (0% duty cycle) or at PWM1 minimum duty cycle when the controlling temperature is below its TMIN − Hysteresis value. 0 = 0% Duty Cycle below TMIN − Hysteresis 1 = PWM1 Minimum Duty Cycle below TMIN − Hysteresis MIN2 R/W When the ADT7463 is in automatic fan speed control mode, this bit defines whether PWM2 is off (0% duty cycle) or at PWM2 minimum duty cycle when the controlling temperature is below its TMIN − Hysteresis value. 0 = 0% Duty Cycle below TMIN − Hysteresis 1 = PWM2 Minimum Duty Cycle below TMIN − Hysteresis MIN3 R/W When the ADT7463 is in automatic fan speed control mode, this bit defines whether PWM3 is off (0% duty cycle) or at PWM3 minimum duty cycle when the controlling temperature is below its TMIN− Hysteresis value. 0 = 0% Duty Cycle below TMIN − Hysteresis 1 = PWM3 Minimum Duty Cycle below TMIN − Hysteresis 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 65. REGISTER 0X63 − ENHANCED ACOUSTICS REGISTER 2 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W ACOU3 R/W Description These bits select the ramp rate applied to the PWM3 output. Instead of PWM3 jumping instantaneously to its newly calculated speed, PWM3 ramps gracefully at the rate determined by these bits. This effect enhances the acoustics of the fan being driven by the PWM3 output. Time Slot Increase 000 = 1 001 = 2 010 = 3 011 = 4 100 = 8 101 = 12 110 = 24 111 = 48 Time for 33% to 100% 35 sec 17.6 sec 11.8 sec 7 sec 4.4 sec 3 sec 1.6 sec 0.8 sec EN3 R/W When this bit is 1, acoustic enhancement is enabled on PWM3 output. ACOU2 R/W These bits select the ramp rate applied to the PWM2 output. Instead of PWM2 jumping instantaneously to its newly calculated speed, PWM2 ramps gracefully at the rate determined by these bits. This effect enhances the acoustics of the fans being driven by the PWM2 output. Time Slot Increase 000 = 1 001 = 2 010 = 3 011 = 4 100 = 8 101 = 12 110 = 24 111 = 48 EN2 R/W Time for 33% to 100% 35 sec 17.6 sec 11.8 sec 7 sec 4.4 sec 3 sec 1.6 sec 0.8 sec When this bit is 1, acoustic enhancement is enabled on PWM2 output. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. http://onsemi.com 43 ADT7463 Table 66. PWM MIN DUTY CYCLE REGISTERS (Note 1) Register Address R/W 0x64 R/W PWM1 Min Duty Cycle Description 0x80 (50% Duty Cycle) Power−On Default 0x65 R/W PWM2 Min Duty Cycle 0x80 (50% Duty Cycle) 0x66 R/W PWM3 Min Duty Cycle 0x80 (50% Duty Cycle) 1. These registers become read−only when the ADT7463 is in automatic fan control mode. Table 67. PWM MIN DUTY CYCLE REGISTER BITS Bit Name R/W PWM Duty Cycle R/W Description These bits define the PWMMIN duty cycle for PWMx. 0x00 = 0% Duty Cycle (Fan Off) 0x40 = 25% Duty Cycle 0x80 = 50% Duty Cycle 0xFF = 100% Duty Cycle (Fan Full Speed) Table 68. TMIN REGISTERS (Note 1) Register Address R/W 0x67 R/W Remote 1 Temperature TMIN 0x5A (90°C) 0x68 R/W Local Temperature TMIN 0x5A (90°C) 0x69 R/W Remote 2 Temperature TMIN 0x5A (90°C) Description (Note 2) Power−On Default 1. These registers become read−only when the Configuration Register 1 Lock bit is set. Further attempts to write to these registers have no effect. 2. These are the TMIN registers for each temperature channel. When the temperature measured exceeds TMIN, the appropriate fan runs at minimum speed and increase with temperature according to TRANGE. Table 69. THERM LIMIT REGISTERS (Note 1) Register Address R/W 0x6A R/W Remote 1 THERM Limit 0x64 (100°C) 0x6B R/W Local THERM Limit 0x64 (100°C) 0x6C R/W Remote 2 THERM Limit 0x64 (100°C) Description (Note 2) Power−On Default 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. 2. If any temperature measured exceeds its THERM limit, all PWM outputs drive their fans at 100% duty cycle. This is a fail−safe mechanism incorporated to cool the system in the event of a critical overtemperature. It also ensures some level of cooling in the event that software or hardware locks up. If set to 0x80, this feature is disabled. The PWM output remains at 100% until the temperature drops below THERM Limit – Hysteresis. If the THERM pin is programmed as an output, exceeding these limits by 0.25°C can cause the THERM pin to assert low as an output. Table 70. TEMPERATURE HYSTERESIS REGISTERS (Note 1) Register Address R/W 0x6D R/W Remote 1 Local Temperature Hysteresis 0x44 0x6E R/W Remote 2 Temperature Hysteresis 0x40 Description (Note 2) Power−On Default 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. 2. Each 4−bit value controls the amount of temperature hysteresis applied to a particular temperature channel. Once the temperature for that channel falls below its TMIN value, the fan remains running at PWMMIN duty cycle until the temperature = TMIN – Hysteresis. Up to 15°C of hysteresis may be assigned to any temperature channel. The hysteresis value chosen also applies to that temperature channel if its THERM limit is exceeded. The PWM output being controlled goes to 100% if the THERM limit is exceeded and remains at 100% until the temperature drops below THERM – Hysteresis. For acoustic reasons, it is recommended that the hysteresis value not be programmed less than 4°C. Setting the hysteresis value lower than 4°C causes the fan to switch on and off regularly when the temperature is close to TMIN. http://onsemi.com 44 ADT7463 Table 71. XOR TREE TEST ENABLE REGISTER (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W 0x6F R/W Description XNOR Tree Test Enable Bit Name XEN If the XEN bit is set to 1, the device enters the XOR tree test mode. Clearing the bit removes the device from the XOR test mode. Description RES Unused. Do not write to these bits. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 72. REMOTE 1 TEMPERATURE OFFSET REGISTER (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W Description 0x70 R/W Remote 1 Temperature Offset R/W Allows a twos complement offset value to be automatically added to or subtracted from the Remote 1 Temperature reading. This is to compensate for any inherent system offsets such as PCB trace resistance. LSB value = 0.25°C. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 73. LOCAL TEMPERATURE OFFSET REGISTER (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W 0x71 R/W Local Temperature Offset Description R/W Allows a twos complement offset value to be automatically added to or subtracted from the local temperature reading. LSB value = 0.25°C. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 74. REMOTE 2 TEMPERATURE OFFSET REGISTER (POWER−ON DEFAULT = 0X00) (Note 1) Register Address R/W Description 0x72 R/W Remote 2 Temperature Offset R/W Allows a twos complement offset value to be automatically added to or subtracted from the Remote 2 temperature reading. This is to compensate for any inherent system offsets such as PCB trace resistance. LSB value = 0.25°C. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. http://onsemi.com 45 ADT7463 Table 75. REGISTER 0X73 − CONFIGURATION REGISTER 2 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W Description 0 AIN1 R/W AIN1 = 0, Speed of 3−wire fans measured using the TACH output from the fan. AIN1 = 1, Pin 11 is reconfigured to measure the speed of 2−wire fans using an external sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration Register 4 (Reg. 0x7D). 1 AIN2 R/W AIN2 = 0, Speed of 3−wire fans measured using the TACH output from the fan. AIN2 = 1, Pin 12 is reconfigured to measure the speed of 2−wire fans using an external sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration Register 4 (Reg. 0x7D). 2 AIN3 R/W AIN3 = 0, Speed of 3−wire fans measured using the TACH output from the fan. AIN3 = 1, Pin 9 is reconfigured to measure the speed of 2−wire fans using an external sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration Register 4 (Reg. 0x7D). 3 AIN4 R/W AIN4 = 0, Speed of 3−wire fans measured using the TACH output from the fan. AIN4 = 1, Pin 14 is reconfigured to measure the speed of 2−wire fans using an external sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration Register 4 (Reg. 0x7D). 4 AVG R/W AVG = 1, Averaging on the temperature and voltage measurements is turned off. This allows measurements on each channel to be made much faster. 5 ATTN R/W ATTN = 1, the ADT7463 removes the attenuators from the 2.5 V, VCCP, 5 V, and 12 V inputs. The inputs can be used for other functions such as connecting up external sensors. 6 CONV R/W CONV = 1, the ADT7463 is put into a single−channel ADC conversion mode. In this mode, the ADT7463 can be made to read continuously from one input only, for example, Remote 1 temperature. It is also possible to start ADC conversions using an external clock on Pin 11 by setting Bit 2 of Test Register 2 (Reg. 0x7F). This mode could be useful if, for example, users wanted to characterize/profile CPU temperature quickly. The appropriate ADC channel is selected by writing to Bits of TACH1 min high byte register (Reg. 0x55). Bits Reg. 0x55 000 001 010 011 100 101 110 111 7 SHDN R/W Channel Selected 2.5V VCCP VCC (3.3V) 5V 12V Remote 1 Temp Local Temp Remote 2 Temp SHDN = 1, ADT7463 goes into shutdown mode. All PWM outputs assert low (or high depending, on state of INV bit) to switch off all fans. The PWM current duty cycle registers read 0x00 to indicate that the fans are not being driven. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 76. REGISTER 0X74 − INTERRUPT MASK REGISTER 1 (POWER−ON DEFAULT = 0X00) Bit Name R/W Description 0 2.5V R/W A 1 masks SMBALERT for out−of−limit conditions on the 2.5 V channel. 1 VCCP R/W A 1 masks SMBALERT for out−of−limit conditions on the VCCP channel. 2 VCC R/W A 1 masks SMBALERT for out−of−limit conditions on the VCC channel. 3 5V R/W A 1 masks SMBALERT for out−of−limit conditions on the 5 V channel. 4 R1T R/W A 1 masks SMBALERT for out−of−limit conditions on the Remote 1 Temperature channel. 5 LT R/W A 1 masks SMBALERT for out−of−limit conditions on the Local Temperature channel. 6 R2T R/W A 1 masks SMBALERT for out−of−limit conditions on the Remote 2 Temperature channel. 7 OOL R/W A 1 masks SMBALERT for any out−of−limit condition in Status Register 2. http://onsemi.com 46 ADT7463 Table 77. REGISTER 0X75 − INTERRUPT MASK REGISTER 2 (POWER−ON DEFAULT = 0X00) Bit Name R/W 0 12V/VC R/W Description 1 OVT Read−only 2 FAN1 R/W A 1 masks SMBALERT for a Fan 1 fault. 3 FAN2 R/W A 1 masks SMBALERT for a Fan 2 fault. 4 FAN3 R/W A 1 masks SMBALERT for a Fan 3 fault. 5 F4P R/W A 1 masks SMBALERT for a Fan 4 fault. If the TACH4 pin is being used as the THERM input, this bit masks SMBALERT for a THERM timer event. 6 D1 R/W A 1 masks SMBALERT for a diode open or short on Remote 1 channel. 7 D2 R/W A 1 masks SMBALERT for a diode open or short on Remote 2 channel. A 1 masks SMBALERT for out−of−limit conditions on the 12 V channel. A 1 masks SMBALERT for overtemperature THERM conditions. Table 78. REGISTER 0X76 − EXTENDED RESOLUTION REGISTER 1 Bit Name R/W Description 12V Read−only 2.5 V LSBs. Holds the 2 LSBs of the 10−bit 2.5 V measurement. VCCP Read−only VCCP LSBs. Holds the 2 LSBs of the 10−bit VCCP measurement. VCC Read−only VCC LSBs. Holds the 2 LSBs of the 10−bit VCC measurement. 5V Read−only 5 V LSBs. Holds the 2 LSBs of the 10−bit 5 V measurement. 1. If this register is read, this register and the registers holding the MSB of each reading are frozen until read. Table 79. REGISTER 0X77 − EXTENDED RESOLUTION REGISTER 2 (Note 1) Name R/W 12V Read−only 12 V LSBs. Holds the 2 LSBs of the 10−bit 12 V measurement. TDM1 Read−only Remote 1 Temperature LSBs. Holds the 2 LSBs of the 10−bit Remote 1 temperature measurement. LTMP Read−only Local Temperature LSBs. Holds the 2 LSBs of the 10−bit local temperature measurement. TDM2 Read−only Remote 2 Temperature LSBs. Holds the 2 LSBs of the 10−bit Remote 2 temperature measurement. Bit Description 1. If this register is read, this register and the registers holding the MSB of each reading are frozen until read. Table 80. REGISTER 0X78 − CONFIGURATION REGISTER 3 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W Description ALERT R/W ALERT = 1, Pin 10 (PWM2/ SMBALERT) is configured as an SMBALERT interrupt output to indicate out−of−limit error conditions. THERM ENABLE R/W THERM ENABLE = 1 enables THERM monitoring functionality on the pin determined by Bit 1 (TH5V) of Configuration Register 4. When THERM is asserted, fans can be run at full speed (if the BOOST bit is set), or a timer can be triggered to time how long THERM has been asserted for. BOOST R/W BOOST = 1, assertion of THERM causes all fans to run at 100% duty cycle for fail−safe cooling. FAST R/W FAST = 1 enables fast TACH measurements on all channels. This increases the TACH measurement rate from once per second, to once every 250 ms (4×). DC1 R/W DC1 = 1 enables TACH measurements to be continuously made on TACH1. DC2 R/W DC2 = 2 enables TACH measurements to be continuously made on TACH2. DC3 R/W DC3 = 1 enables TACH measurements to be continuously made on TACH3. DC4 R/W DC4 = 1 enables TACH measurements to be continuously made on TACH4. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. http://onsemi.com 47 ADT7463 Table 81. REGISTER 0X79 − THERM STATUS REGISTER (POWER−ON DEFAULT = 0X00) Bit Name R/W Description TMR Read−only Times how long THERM input is asserted. These seven bits read 0 until the THERM assertion time exceeds 45.52 ms. ASRT/TMR0 Read−only Is set high on the assertion of the THERM input. Cleared on read. If the THERM assertion time exceeds 45.52 ms, this bit is set and becomes the LSB of the 8−bit TMR reading. This allows THERM assertion times from 45.52 ms to 5.82 s to be reported back with a resolution of 22.76 ms. Table 82. REGISTER 0X7A − THERM LIMIT REGISTER (POWER−ON DEFAULT = 0X00) Bit Name R/W LIMT R/W Description Sets maximum THERM assertion length allowed before an interrupt is generated. This is an 8−bit limit with a resolution of 22.76 ms allowing THERM assertion limits of 45.52 ms to 5.82 s to be programmed. If the THERM assertion time exceeds this limit, Bit 5 (F4P) of Interrupt Status Register 2 (Reg. 0x42) is set. If the limit value is 0x00, an interrupt is generated immediately upon the assertion of the THERM input. Table 83. REGISTER 0X7B − FAN PULSES PER REVOLUTION REGISTER (POWER−ON DEFAULT = 0X55) Bit Mnemonic R/W FAN1 R/W Sets number of pulses to be counted when measuring Fan1 speed. Can be used to determine fan’s pulses per revolution for unknown fan type. Pulses Counted 00 = 1 01 = 2 (Default) 10 = 3 11 = 4 Description FAN2 R/W Sets number of pulses to be counted when measuring FAN2 speed. Can be used to determine fan’s pulses per revolution for unknown fan type. Pulses Counted 00 = 1 01 = 2 (Default) 10 = 3 11 = 4 FAN3 R/W Sets number of pulses to be counted when measuring FAN3 speed. Can be used to determine fan’s pulses per revolution for unknown fan type. Pulses Counted 00 = 1 01 = 2 (Default) 10 = 3 11 = 4 FAN4 R/W Sets number of pulses to be counted when measuring FAN4 speed. Can be used to determine fan’s pulses per revolution for unknown fan type. Pulses Counted 00 = 1 01 = 2 (Default) 10 = 3 11 = 4 http://onsemi.com 48 ADT7463 Table 84. REGISTER 0X7D − CONFIGURATION REGISTER 4 (POWER−ON DEFAULT = 0X00) (Note 1) Bit Name R/W AL2.5V R/W AL2.5V = 1, Pin 14 (2.5 V/SMBALERT) is configured as an SMBALERT interrupt output to indicate out−of−limit error conditions. AL2.5V = 0, Pin 14 (2.5 V/SMBALERT) is configured as a 2.5 V measurement input. Description TH5V R/W TH5V = 1, Pin 20 (5V/THERM) is configured as THERM pin. For THERM Monitoring, Bit 1 (THERM Timer) of Configuration Register 3 must also be set. TH5V = 0, Pin 20 (5V/THERM) is configured as 5 V measurement input. AINL R/W These two bits define the input threshold for 2−wire fan speed measurements: 00 = ±20 mV 01 = ±40 mV 10 = ±80 mV 11 = ±130 mV RES Unused. 1. This register becomes read−only when the Configuration Register 1 Lock bit is set to 1. Further attempts to write to this register have no effect. Table 85. REGISTER 0X7E − MANUFACTURER’S TEST REGISTER 1 (POWER−ON DEFAULT = 0X00) Bit Name R/W RES Read−only Description Manufacturer’s Test Register. These bits are reserved for manufacturer’s test purposes and should NOT be written to under normal operation. Table 86. REGISTER 0X7F − MANUFACTURER’S TEST REGISTER 2 (POWER−ON DEFAULT = 0X00) Bit Name R/W RES Read−only Description Manufacturer’s Test Register. These bits are reserved for manufacturer’s test purposes and should NOT be written to under normal operation. Table 87. ORDERING INFORMATION Device Number Temperature Range Package Type Package Option Shipping† ADT7463ARQZ−REEL −40°C to +120°C 24−lead QSOP RQ−24 2,500 Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. *The “Z’’ suffix indicates Pb−Free part. Pentium is a registered trademark of Intel Corporation. http://onsemi.com 49 MECHANICAL CASE OUTLINE PACKAGE DIMENSIONS QSOP24 NB CASE 492B−01 ISSUE A DATE 06 MAY 2008 2X SCALE 2:1 NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b DOES NOT INCLUDE DAMBAR PROTRUSION. 4. DIMENSION D DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. MOLD FLASH, PROTRUSIONS, OR GATE BURRS SHALL NOT EX­ CEED 0.15 PER SIDE. DIMENSION E1 DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. IN­ TERLEAD FLASH OR PROTRUSION SHALL NOT EX­ CEED 0.15 PER SIDE. D AND E1 ARE DETERMINED AT DATUM H. 5. DATUMS A AND B ARE DETERMINED AT DATUM H. 0.20 C D D A 24 D C 13 GAUGE PLANE L2 E E1 C L DETAIL A 2X 2X 12 TIPS 0.20 C D 1 12 24X e B b 0.25 0.25 C D M C A-B D A 0.10 C 0.10 C A1 24X C SEATING PLANE 24X 0.42 1.12 24 h x 45 _ H SOLDERING FOOTPRINT 24X DIM A A1 b C D E E1 e h L L2 M DETAIL A M MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.20 0.30 0.19 0.25 8.65 BSC 6.00 BSC 3.90 BSC 0.635 BSC 0.22 0.50 0.40 1.27 0.25 BSC 0_ 8_ GENERIC MARKING DIAGRAM* 13 xxxxxxxxx AWLYWW 6.40 1 12 0.635 PITCH DOCUMENT NUMBER: DESCRIPTION: DIMENSIONS: MILLIMETERS 98AON04474D QSOP24 NB xxx A WL Y WW = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week *This information is generic. Please refer to device data sheet for actual part marking. Pb−Free indicator, “G”, may or not be present. Electronic versions are uncontrolled except when accessed directly from the Document Repository. Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red. PAGE 1 OF 1 ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. 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