ADT7476AARQZ-REEL7 ON Semiconductor, ADT7476AARQZ-REEL7 Datasheet - Page 9

• Manufacturer Part Number: ADT7476AARQZ-REEL7
• Description: IC REMOTE THERMAL CTRLR 24-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7476AARQZ-REEL7

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 24-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Product Description
multiple fan controller for any system requiring thermal
monitoring and cooling. The device communicates with the
system via a serial system management bus. The serial bus
controller has a serial data line for reading and writing
addresses and data (Pin 1), and an input line for the serial
clock (Pin 2). All control and programming functions for the
ADT7476A are performed over the serial bus. In addition,
a pin can be reconfigured as an SMBALERT output to signal
out-of-limit conditions.
Feature Comparisons Between ADT7476A
and ADT7468
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The ADT7476A is a complete thermal monitor and
Dynamic T
associated registers are no longer available in the
ADT7476A. The following related registers are gone:
Previously (in the ADT7468), T
of the automatic fan control algorithm. T
defines a true temperature range (in the ADT7476A).
Acoustic filtering is now assigned to temperature zones,
not to fans. Available smoothing times have been
increased for better acoustic performance.
Temperature measurements are now made with two
switching currents instead of three. SRC is not available
in the ADT7476A.
High frequency PWM can now be enabled/disabled on
each PWM output individually.
THERM can now be enabled/disabled on each
temperature channel individually.
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Calibration Control 1 (0x36)
Calibration Control 2 (0x37)
Operating Point (0x33, 0x34, and 0x35)
MIN
, dynamic operating point, and
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
RANGE
defined the slope
Figure 13. ADT7476A Configuration
RANGE
now
http://onsemi.com
TACH2
PWM3
TACH3
D1+
D1–
V
+5V
+12V
CC
IN
IN
ADT7476A
/VID5
VID[0:4]/VID[0:5]
9
GND
SMBALERT
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Recommended Implementation
the system designer to use the following features:
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Configuring the ADT7476A as shown in Figure 13 allows
THERM
The ADT7476A does not support full shutdown mode.
The ADT7476A offers increased temperature accuracy
on all temperature channels.
The ADT7476A defaults to twos complement
temperature measurement mode.
Some pins have swapped/added functions.
The powerup routine for the ADT7476A is simplified.
The ADT7476A has a higher maximum input voltage
TACH/PWM spec, supporting a wider range of fans.
V
Configuration Register 1 (0x40).
Two PWM outputs for fan control of up to three fans
(the front and rear chassis fans are connected in
parallel).
Three TACH fan speed measurement inputs.
V
CPU temperature measured using Remote 1
temperature channel.
Remote temperature zone measured through Remote 2
temperature channel.
Local temperature zone measured through the internal
temperature channel.
Bidirectional THERM pin. This feature allows Intel
Pentium 4 PROCHOT monitoring and can function as
an overtemperature THERM output. It can alternatively
be programmed as an SMBALERT system interrupt
output.
TACH1
PWM1
CORE_LOW_ENABLE
CC
SDA
SCL
D2+
D2–
measured internally through Pin 4.
5(VRM9)/6(VRM10)
PROCHOT
has been reallocated to Bit 7 of