ADT7473 Datasheet, PDF (1/76 Pages) Analog Devices – dBCool Remote Thermal Monitor and Fan Controller

dBCool^® Remote Thermal
Monitor and Fan Controller
ADT7473
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
Series resistance cancellation on the remote channel
Extended temperature measurement range, up to 191°C
Dynamic TMIN control mode optimizes system acoustics
intelligently
Automatic fan speed control mode controls system cooling
based on measured temperature
The ADT7473 dBCool controller is a thermal monitor and
multiple PWM fan controller for noise sensitive or power
sensitive applications requiring active system cooling. The
ADT7473 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.
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
The automatic fan speed control loop optimizes fan speed for a
given temperature. A unique dynamic TMIN control mode
enables the system thermals/acoustics to be intelligently
managed. The effectiveness of the system’s thermal solution can
be monitored using the THERM input. The ADT7473 also
3-wire and 4-wire fan speed measurement
Limit comparison of all monitored values
Meets SMBus 2.0 electrical specifications
(fully SMBus 1.1 compliant)
provides critical thermal protection to the system using the
bidirectional THERM pin as an output to prevent system or
component overheating.
Fully ROHS compliant
FUNCTIONAL BLOCK DIAGRAM
SCL SDA SMBALERT
ADT7473
SERIAL BUS
INTERFACE
PWM1
PWM2
PWM3
TACH1
TACH2
TACH3
TACH4
THERM
V_CC
D1+
D1–
D2+
D2–
V_CCP
PWM
REGISTERS
AND
CONTROLLERS
(HF AND LF)
ACOUSTIC
ENHANCEMENT
CONTROL
V_CC TO ADT7473
SRC
BAND GAP
TEMP SENSOR
FAN
SPEED
COUNTER
PERFORMANCE
MONITORING
THERMAL
PROTECTION
INPUT
SIGNAL
CONDITIONING
AND
ANALOG
MULTIPLEXER
AUTOMATIC
FAN SPEED
CONTROL
DYNAMIC
T_MIN
CONTROL
10-BIT
ADC
BAND GAP
REFERENCE
ADDRESS
POINTER
REGISTER
PWM
CONFIGURATION
REGISTERS
INTERRUPT
MASKING
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATORS
VALUE AND
LIMIT
REGISTERS
GND
Figure 1.
Rev. A
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