ADT7475 Analog Devices, Inc., ADT7475 Datasheet - Page 9

• Manufacturer Part Number: ADT7475
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

PRODUCT DESCRIPTION
The ADT7475 is a complete thermal monitor and multiple fan
controller for any system requiring thermal monitoring and
cooling. The device communicates with the system via a serial
system management bus. The serial bus controller has a serial
data line for reading and writing addresses and data (Pin 16),
and an input line for the serial clock (Pin 1). All control and
programming functions for the ADT7475 are performed over
the serial bus. In addition, a pin can be reconfigured as an
SMBALERT output to signal out-of-limit conditions.
QUICK COMPARISON BETWEEN ADT7473 AND
ADT7475
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The ADT7475 is similar to the ADT7473 in that it is powered
by a supply no greater than 3.6 V. Exceeding this specification
results in irreversible damage to the ADT7475. Signal pins
(TACH/PWM) should be pulled up or clamped to 3.6 V
maximum. See the Specifications section for more information.
The ADT7473 supports advanced dynamic T
while the ADT7475 does not.
Acoustic smoothing is improved on the ADT7475.
THERM can be selected as an output only on the
ADT7475.
The ADT7475 has two additional configuration registers.
The ADT7475 has other minor register changes.
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
MIN
features
Figure 13. ADT7475 Configuration
TACH2
PWM3
TACH3
D1+
D1–
Rev. B | Page 9 of 68
ADT7475
GND
SMBALERT
THERM
RECOMMENDED IMPLEMENTATION
Configuring the ADT7475 as shown in Figure 13 allows the
system designer to use the following features:
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TACH1
PWM1
SDA
SCL
D2+
D2–
Two PWM outputs for fan control of up to three fans
(the front and rear chassis fans are connected in parallel).
Three TACH fan speed measurement inputs.
V
CPU temperature measured using the Remote 1
temperature channel.
Ambient temperature measured through the Remote 2
temperature channel.
Bidirectional THERM pin. This feature allows Intel
Pentium 4 PROCHOT monitoring and can function as
an overtemperature THERM output. The THERM pin
can alternatively be programmed as an SMBALERT system
interrupt output.
CC
measured internally through Pin 3.
PROCHOT
CPU FAN
ICH
CPU
ADT7475