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Semiconductor Components Industries, LLC, 2012
July, 2012 − Rev. 5
1 Publication Order Number:
ADT7490/D
ADT7490
Remote Thermal Monitor
and Fan Controller with
PECI Interface
The ADT7490 is a thermal monitor and multiple PWM fan
controller for noise-sensitive or power-sensitive applications requiring
active system cooling. The ADT7490 includes a local temperature
sensor, two remote temperature sensors including series resistance
cancellation, and monitors CPU temperature with a PECI interface.
The ADT7490 can drive a fan using either a low or high frequency
drive signal, and measure and control the speed of up to four fans so
they operate at the lowest possible speed for minimum acoustic noise.
The automatic fan speed control loop optimizes fan speed
for a given temperature using the PECI, remote, or local temperature
information. The effectiveness of the system’s thermal solution can be
monitored using the THERM
input. The ADT7490 also provides
critical thermal protection to the system using the bidirectional
THERM
/SMBALERT pin as an output to prevent system or
component overheating.
Features
Temperature Measurement
1 Local On-Chip Temperature Sensor
2 Remote Temperature Sensors
3 Current External Temperature Sensors with Series Resistance
Cancellation (SRC)
PECI Interface for CPU Thermal Information and Support of Up
to 4 PECI Inputs on 1 Pin
Fan Drive and Fan Speed Control
3 High Frequency or Low Frequency PWM Outputs for Use with
3-wire or 4-wire Fans
4 TACH Inputs to Measure Fan Speed
OS Independent Automatic Fan Speed Control Based on Thermal
Information
Dynamic T
MIN
Control Mode to Optimize System Acoustics
Default Startup at 100% PWM for All Fans for Robust Operation
Bidirectional THERM/SMBALERT Pin to Flag Out-of-Limit and
Overtemperature Conditions
GPIO Functionality to Support Extra Features
Can be Used for Loadline Setting for Voltage Regulation, LED
Control, or Other Functions
I
MON
Monitoring for CPU Current and Power Information
Footprint and Register Compatible with ADT7473/ADT7475/
ADT7476/ADT7476A Family of Fan Controllers
SMBus Interface with Addressing Capability for Up to 3 Devices
Applications
Personal Computers
Servers
http://onsemi.com
PIN ASSIGNMENT
QSOP−24 NB
CASE 492B
# = Pb-Free Package
See detailed ordering and shipping information in the package
dimensions section on page 74 of this data sheet.
ORDERING INFORMATION
MARKING DIAGRAMS
ADT7490
ARQZ
#DateCode
TOP MARKING
Assembly Lot
BOTTOM MARKING
1
+2.5V
IN
/THERM
PWM1/XTO
V
CCP
+12V
IN
+5V
IN
D1+
*TACH4/THERM
/SMBALERT/ADDR SELECT
I
MON
SDA
SCL
GND
V
CC
GPIO1
GPIO2
PECI
PWM2/
SMBALERT
24
23
22
21
20
19
18
17
8
7
6
5
4
3
2
1
ADT7490
16
9
15
10
14
11
13
12
V
TT
TACH3
TACH1
TACH2
D1−
D2+
D2−
PWM3/ADDREN
*
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