Temperature Sensor Hub and Fan Controller

Preliminary Technical Data

ADT7470

Rev. PrA

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FEATURES

Monitors up to 10 remote temperature sensors

Monitors and controls speed of up to 4 fans independently

PWM outputs drive each fan under software control

FULL_SPEED input allows fans to be blasted 100% by

external hardware

SMBALERT interrupt signals failures to system controller

Tristate ADDR pin allows up to 3 devices on a single bus

Temperature decoder interprets TMP05/TMP06 temperature

Limit comparison of all monitored values

Meets SMBus 2.0 electrical specifications

(fully SMBus 1.1 compliant)

Footprint compatible with ADT7460

APPLICATIONS

Servers

Networking and telecommunications equipment

Desktops

GENERAL DESCRIPTION

The ADT7470 controller is a multichannel temperature sensor

and PWM fan controller and fan speed monitor for noise-

sensitive systems requiring active system cooling. It is designed

using a service processor. The aim is to quickly develop systems

that are modular and can easily be expanded depending on the

system’s cooling requirements. The device can monitor up to ten

temperature sensors. It can also monitor and control the speed

of four fans so that they operate at the lowest possible speed for

minimum acoustic noise. A FULL_SPEED input is provided to

allow the fans to be “blasted” to 100% via external hardware

control, under extreme thermal conditions or on system startup.

An SMBALERT interrupt communicates error conditions such

as fan underspeed, fan failure to the system service processor.

Individual error conditions can then be read from status registers

all PWM outputs can be programmed to automatically adjust to

100% to provide failsafe cooling.

FUNCTIONAL BLOCK DIAGRAM

FULL_SPEED

PWM1

PWM2

PWM3

PWM4

TACH1

TACH2

TACH3

TACH4

TMP_START

TMP_IN

ADDR

SDA SCL SMBALERT

ADDRESS

POINTER

REGISTER

PWM

CONFIG

REGISTERS

INTERRUPT

MASKING

INTERRUPT

STATUS

REGISTERS

LIMIT

COMPARATORS

VALUE AND

LIMIT

REGISTERS

SERIAL BUS

INTERFACE

SMBus

ADDRESS

SELECTION

AUTOMATIC

FAN SPEED

CONTROL

PWM

REGISTERS

AND

CONTROLLERS

FAN SPEED

COUNTERS

TEMPERATURE

DECODER

ADT7470

Figure 1.

Protected by Patent Numbers US6,188,189, US6,169,442, US6,097,239, US5,982,221, US5,867,012. Other patents pending.