ADT7476ARQH ONSEMI [ON Semiconductor], ADT7476ARQH Datasheet - Page 9

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ADT7476ARQH

Manufacturer Part Number
ADT7476ARQH
Description
dBCOOL Remote Thermal Controller and Voltage Monitor
Manufacturer
ONSEMI [ON Semiconductor]
Datasheet
Product Description
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 ADT7476 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 ADT7476 and ADT7468
The ADT7476 is a complete thermal monitor and multiple
Dynamic T
associated registers are no longer available in the
ADT7476. 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 ADT7476).
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 ADT7476.
High frequency PWM can now be enabled/disabled on
each PWM output individually.
THERM can now be enabled/disabled on each
temperature channel individually.
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
RANGE
Figure 13. ADT7476 Configuration
now
http://onsemi.com
TACH2
PWM3
TACH3
D1+
D1–
V
+5V
+12V
CC
IN
IN
ADT7476
/VID5
VID[0:4]/VID[0:5]
9
GND
SMBALERT
Recommended Implementation
the system designer to use the following features:
Configuring the ADT7476 as shown in Figure 13 allows
THERM
The ADT7476 does not support full shutdown mode.
The ADT7476 offers increased temperature accuracy
on all temperature channels.
The ADT7476 defaults to twos complement
temperature measurement mode.
Some pins have swapped/added functions.
The powerup routine for the ADT7476 is simplified.
The ADT7476 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

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