ADT7476A Datasheet, PDF (1/72 Pages) Analog Devices – dBCool Remote Thermal Controller and Voltage Monitor

dBCool^™ Remote Thermal
Controller and Voltage Monitor
ADT7476A
FEATURES
Monitors up to five voltages
Improved TACH and PWM performance
Controls and monitors up to four fans
High and low frequency fan drive signal
One on-chip and two 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
Monitors performance impact of Intel® Pentium® 4 processor
Thermal control circuit via THERM input
3-wire and 4-wire fan speed measurement
Limit comparison of all monitored values
5 V support on all TACH and PWM channels
Meets SMBus 2.0 electrical specifications
GENERAL DESCRIPTION
The ADT7476A dBCOOL controller is a thermal monitor
and multiple PWM fan controller for noise-sensitive or power-
sensitive applications requiring active system cooling. The
ADT7476A can drive a fan using either a low or high frequency
drive signal and can monitor the temperature of up to two
remote sensor diodes plus its own internal temperature. The
part also measures and controls the speed of up to four fans, so
the fans operate at the lowest possible speed for minimum
acoustic noise.
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.
The ADT7476A also provides critical thermal protection to
the system using the bidirectional THERM pin as an output
to prevent system or component overheating.
VID5/GPIO5
VID4/GPIO4
VID3/GPIO3
VID2/GPIO2
VID1/GPIO1
VID0/GPIO0
GPIO6
PWM1
PWM2
PWM3
TACH1
TACH2
TACH3
TACH4
THERM
V_CC
D1+
D1–
D2+
D2–
+5V_IN
+12V_IN
+2.5V_IN
V_CCP
FUNCTIONAL BLOCK DIAGRAM
ADDR
ADDREN SELECT SCL SDA SMBALERT
PWM
REGISTERS
AND
CONTROLLERS
(HF AND LF)
V_CC TO ADT7476A
BAND GAP
TEMP. SENSOR
VID/GPIO
REGISTER
AUTOMATIC
FAN SPEED
CONTROL
FAN
SPEED
COUNTER
PERFORMANCE
MONITORING
THERMAL
PROTECTION
INPUT
SIGNAL
CONDITIONING
AND
ANALOG
MULTIPLEXER
SMBus
ADDRESS
SELECTION
SERIAL BUS
INTERFACE
ADT7476A
ADDRESS
POINTER
REGISTER
PWM
CONFIGURATION
REGISTERS
INTERRUPT
MASKING
ACOUSTIC
ENHANCEMENT
CONTROL
10-BIT
ADC
BAND GAP
REFERENCE
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATORS
VALUE AND
LIMIT
REGISTERS
GND
Figure 1.
Rev. 0
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.