ADT7475
TABLE OF CONTENTS
Features .............................................................................................. 1
Temperature Measurement Method........................................ 15
Factors Affecting Diode Accuracy........................................... 17
Additional ADC Functions for Temperature Measurement 18
Limits, Status Registers, and Interrupts....................................... 20
Limit Values ................................................................................ 20
Interrupt Status Registers.......................................................... 21
General Description......................................................................... 1
Functional Block Diagram .............................................................. 1
Specifications..................................................................................... 3
Timing Diagram ........................................................................... 4
Absolute Maximum Ratings............................................................ 5
Thermal Characteristics .............................................................. 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Typical Performance Characteristics ............................................. 7
Product Description......................................................................... 9
Quick Comparison Between ADT7473 and ADT7475 .......... 9
Recommended Implementation................................................. 9
Serial Bus Interface......................................................................... 10
Write Operations ........................................................................ 11
Read Operations......................................................................... 12
Alert Response Address............................................................. 12
SMBus Timeout .......................................................................... 12
Virus Protection.......................................................................... 12
Voltage Measurement Input...................................................... 12
Analog-to-Digital Converter .................................................... 12
Input Circuitry............................................................................ 13
Voltage Measurement Registers................................................ 13
VCCP Limit Registers ................................................................... 13
Extended Resolution Registers ................................................. 13
Additional ADC Functions for Voltage Measurements ........ 13
Timer ........................................................................... 23
THERM
Fan Drive Using PWM Control ............................................... 26
Operating from 3.3 V Standby ................................................. 31
Standby Mode ............................................................................. 31
XNOR Tree Test Mode .............................................................. 31
Power-On Default ...................................................................... 32
Programming the Automatic Fan Speed Control Loop............ 33
Automatic Fan Control Overview............................................ 33
Step 1: Hardware Configuration .............................................. 34
Step 2: Configuring the Mux .................................................... 37
Step 3: TMIN Settings for Thermal Calibration Channels ...... 39
Step 4: PWMMIN for Each PWM (Fan) Output ...................... 40
Step 5: PWMMAX for PWM (Fan) Outputs.............................. 40
Step 6: TRANGE for Temperature Channels................................ 41
Step 7: TTHERM for Temperature Channels ............................... 44
Step 8: THYST for Temperature Channels.................................. 45
Register Tables ................................................................................ 48
Outline Dimensions....................................................................... 65
Ordering Guide .......................................................................... 65
REVISION HISTORY
2/06—Rev. 0 to Rev. A
Changes to Power-On Default Section........................................ 32
Changes to Step 5: PMWMAX For PWM (Fan)
Outputs Section .............................................................................. 40
Changes to Table 14 ....................................................................... 48
Changes to Table 23 ....................................................................... 53
Changes to Table 43 ....................................................................... 60
Changes to Table 1............................................................................ 3
Changes to Quick Comparison Between ADT7473 and
ADT7475 Section ............................................................................. 9
Changes to Analog-to-Digital Converter section ...................... 13
Changes to TACH Inputs Section ................................................ 27
Changes to Fan Speed Measurement Section ............................. 28
Inserted Figure 42........................................................................... 32
7/05—Revision 0: Initial Version
Rev. A | Page 2 of 68