ADT7476 Datasheet, PDF (1/72 Pages) Analog Devices – dBCool Remote Thermal Controller and Voltage Monitor

dBCool^™ Remote Thermal
Controller and Voltage Monitor
ADT7476
FEATURES
Monitors up to 5 voltages
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
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
Meets SMBus 2.0 electrical specifications
GENERAL DESCRIPTION
The ADT7476 dBCool controller is a thermal monitor
and multiple PWM fan controller for noise-sensitive or power-
sensitive applications requiring active system cooling. The
ADT7476 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.
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 ADT7476 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
ADDR
ADDREN SELECT SCL SDA SMBALERT
VID5
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
PWM
REGISTERS
AND
CONTROLLERS
(HF AND LF)
V_CC TO ADT7476
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
ADT7476
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. A
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