ADT7470 Datasheet, PDF (1/40 Pages) Analog Devices – Temperature Sensor Hub and Fan Controller

Temperature Sensor Hub and Fan Controller
Preliminary Technical Data
ADT7470
FEATURES
GENERAL DESCRIPTION
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
sensors and communicates values over I²C bus
Limit comparison of all monitored values
Supports fast I²C standard (400 kHz max)
Meets SMBus 2.0 electrical specifications
(fully SMBus 1.1 compliant)
Footprint compatible with ADT7460
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
to interface directly to an I²C bus and control/monitor the fans
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.
APPLICATIONS
Servers
Networking and telecommunications equipment
Desktops
Individual error conditions can then be read from status registers
over the I²C bus. In the event of a fan failure condition, any or
all PWM outputs can be programmed to automatically adjust to
100% to provide failsafe cooling.
FUNCTIONAL BLOCK DIAGRAM
ADDR
SDA SCL SMBALERT
ADT7470
FULL_SPEED
SMBus
ADDRESS
SELECTION
SERIAL BUS
INTERFACE
ADDRESS
POINTER
REGISTER
PWM1
PWM2
PWM3
PWM4
TACH1
TACH2
TACH3
TACH4
TMP_START
TMP_IN
PWM
REGISTERS
AND
CONTROLLERS
AUTOMATIC
FAN SPEED
CONTROL
FAN SPEED
COUNTERS
TEMPERATURE
DECODER
PWM
CONFIG
REGISTERS
INTERRUPT
MASKING
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATORS
VALUE AND
LIMIT
REGISTERS
Figure 1.
Protected by Patent Numbers US6,188,189, US6,169,442, US6,097,239, US5,982,221, US5,867,012. Other patents pending.
Rev. PrA
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