ADT7468
TABLE OF CONTENTS
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Typical Performance Characteristics ............................................. 8
Product Description....................................................................... 10
Comparison between ADT7463 and ADT7468..................... 10
Recommended Implementation............................................... 11
Serial Bus Interface......................................................................... 12
Write Operations ........................................................................ 13
Read Operations ......................................................................... 14
SMBus Timeout .......................................................................... 14
VID Code Monitoring ................................................................... 15
VID Code Registers.................................................................... 15
Analog-to-Digital Converter ........................................................ 16
Voltage Measurement Input...................................................... 16
Additional ADC Functions for Voltage Measurements ........ 16
Temperature Measurement ....................................................... 18
PWM Logic State........................................................................ 33
Fan Speed Control...................................................................... 34
Miscellaneous Functions ............................................................... 35
Operating from 3.3 V Standby.................................................. 35
XNOR Tree Test Mode............................................................... 35
Power-On Default ...................................................................... 35
Automatic Fan Control Overview................................................ 37
Dynamic TMIN Control Mode.................................................... 38
Programming the Automatic Fan Speed Control Loop ............ 40
Step 1: Hardware Configuration .............................................. 40
Step 2: Configuring the Mux .................................................... 43
Step 3: TMIN Settings for Thermal Calibration Channels....... 45
Step 4: PWMMIN for Each PWM (Fan) Output ...................... 46
Step 5: PWMMAX for PWM (Fan) Outputs.............................. 46
Step 6: TRANGE for Temperature Channels................................ 47
Step 7: TTHERM for Temperature Channels ............................... 50
Step 8: THYST for Temperature Channels.................................. 51
Step 9: Operating Points for Temperature Channels............. 52
Step 10: High and Low Limits for Temperature Channels ... 53
Step 11: Monitoring THERM ................................................... 56
Step 12: Ramp Rate for Acoustic Enhancement..................... 57
Enhancing System Acoustics......................................................... 59
Acoustic Enhancement Mode Overview ................................ 59
Register Tables................................................................................. 61
ADT7468 Programming Block Diagram .................................... 80
Outline Dimensions....................................................................... 81
Ordering Guide .......................................................................... 81
Additional ADC Functions for
Temperature Measurement ....................................................... 21
Limits, Status Registers, and Interrupts....................................... 22
Limit Values................................................................................. 22
Status Registers ........................................................................... 23
Interrupts..................................................................................... 23
Active Cooling ................................................................................ 28
Driving the Fan Using PWM Control ..................................... 28
Laying Out 2-Wire and 3-Wire Fans ....................................... 30
Fan Speed Measurement............................................................ 31
Fan Spin-Up ................................................................................ 33
REVISION HISTORY
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