ADT7475 Datasheet, PDF (1/68 Pages) Analog Devices – dBCool Remote Thermal Monitor and Fan Controller

dBCool^® Remote Thermal
Monitor and Fan Controller
ADT7475
FEATURES
GENERAL DESCRIPTION
Controls and monitors up to 4 fans
High and low frequency fan drive signal
1 on-chip and 2 remote temperature sensors
Extended temperature measurement range, up to 191°C
Automatic fan speed control mode controls system cooling
based on measured temperature
Enhanced acoustic mode dramatically reduces user
perception of changing fan speeds
Thermal protection feature via THERM output
The ADT7475 dBCool controller is a thermal monitor and
multiple PWM fan controller for noise-sensitive or power-
sensitive applications requiring active system cooling. The
ADT7475 can drive a fan using either a low or high frequency
drive signal, monitor the temperature of up to two remote
sensor diodes plus its own internal temperature, and measure
and control the speed of up to four fans, so they operate at the
lowest possible speed for minimum acoustic noise.
Monitors performance impact of Intel® Pentium® 4 processor
Thermal control circuit via THERM input
3-wire and 4-wire fan speed measurement
The automatic fan speed control loop optimizes fan speed
for a given temperature. The effectiveness of the system’s
thermal solution can be monitored using the THERM input.
Limit comparison of all monitored values
Meets SMBus 2.0 electrical specifications
(fully SMBus 1.1 compliant)
Fully RoHS compliant
The ADT7475 also provides critical thermal protection to the
system using the bidirectional THERM pin as an output to
prevent system or component overheating.
FUNCTIONAL BLOCK DIAGRAM
SCL SDA SMBALERT
PWM1
PWM2
PWM3
TACH1
TACH2
TACH3
TACH4
THERM
V_CC
D1+
D1–
D2+
D2–
V_CCP
ADT7475
SERIAL BUS
INTERFACE
PWM
REGISTERS
AND
CONTROLLERS
(HF AND LF)
ACOUSTIC
ENHANCEMENT
CONTROL
AUTOMATIC
FAN SPEED
CONTROL
V_CC TO ADT7475
FAN
SPEED
COUNTER
PERFORMANCE
MONITORING
THERMAL
PROTECTION
ADDRESS
POINTER
REGISTER
PWM
CONFIGURATION
REGISTERS
INTERRUPT
MASKING
INTERRUPT
STATUS
REGISTERS
BAND GAP
TEMPERATURE
SENSOR
INPUT
SIGNAL
CONDITIONING
AND
ANALOG
MULTIPLEXER
10-BIT
ADC
BAND GAP
REFERENCE
GND
Figure 1.
LIMIT
COMPARATORS
VALUE AND
LIMIT
REGISTERS
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
www.analog.com
Fax: [phone]
©2006 Analog Devices, Inc. All rights reserved.