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ADT7470

Data Sheet

Rev. E | Page 2 of 40

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Serial Bus Timing Specifications................................................ 4

Absolute Maximum Ratings............................................................ 5

Thermal Characteristics .............................................................. 5

ESD Caution.................................................................................. 5

Pin Configuration and Function Descriptions............................. 6

Functional Description.................................................................... 7

General Description..................................................................... 7

Configuration Register 1 (Address 0x40).................................. 7

Configuration Register 2 (Address 0x74).................................. 7

ID Registers ................................................................................... 7

General-Purpose I/O Pins (Open Drain)...................................... 8

SMBus/I2C Serial Interface.............................................................. 9

Address Selection ......................................................................... 9

Serial Bus Protocol ....................................................................... 9

Write Operations ........................................................................ 11

Read Operations ......................................................................... 12

SMBus Timeout .......................................................................... 12

Temperature Measurement Using TMP05/TMP06 ................... 13

Measuring Temperature ............................................................ 13

Temperature ReadBack By the Host ........................................ 14

Temperature Data Format......................................................... 14

Temperature Measurement Limits........................................... 15

Thermal Zones for Automatic Fan Control............................ 15

Limit and Status Registers ............................................................. 16

Limit Values ................................................................................ 16

Temperature Limits.................................................................... 16

Fan Speed Limits ........................................................................ 16

Out-of-Limit Comparisons....................................................... 16

Status Registers ........................................................................... 17

SMBALERT Interrupt................................................................ 18

Fan Drive Using PWM Control.................................................... 20

High Frequency Fan Drive........................................................ 20

Low Frequency Fan Drive ......................................................... 20

Setting the Fan Drive Frequency.............................................. 21

Inverted PWM Output .............................................................. 21

Fan Full Speed Function............................................................ 21

Fan Speed Measurement................................................................ 22

Tach Inputs.................................................................................. 22

Fan Speed Measurement ........................................................... 23

Manual Fan Speed Control ........................................................... 25

Setting the PWM Duty Cycle ................................................... 25

Automatic Fan Speed Control ...................................................... 26

Detailed Register Descriptions ..................................................... 29

Outline Dimensions....................................................................... 39

Ordering Guide .......................................................................... 39

REVISION HISTORY

4/13—Rev. D to Rev. E

Changed Input Low Voltage, VIL from 0.4 V to 1.0 V and Added

Test Conditions/Comments; Table 1.............................................. 3

3/13—Rev. C to Rev. D

Changes to Calculating Fan Speed and Tachometer Limits

Section.............................................................................................. 24

Changes to Bit 3, Table 43.............................................................. 35

Updated Outline Dimensions....................................................... 39

7/09—Rev. B to Rev. C

Changes to Functional Description Section ................................. 7

Added Temperature Data Format Section .................................. 14

Additions to Fan Drive Using PWM Control Section............... 20

Additions to Manual Fan Speed Control Section ...................... 25

Additions to Automatic Fan Speed Control Section ................. 26

7/05—Rev. A to Rev. B

References to PWM_IN changed to TMP_IN ...............Universal

Changes to TMIN Registers Section ..................................................7

Added Address Selection Section....................................................7

Added Thermal Zones Section..................................................... 12

Added Temperature Reading Section.......................................... 13

Added Note to Table 39 ................................................................. 32

2/05—Rev. 0 to Rev. A

Added General-Purpose I/O Pins (Open Drain) Section......... 11

11/04—Revision 0: Initial Version

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