ADT7476
Rev. B | Page 11 of 72
PRODUCT DESCRIPTION
The ADT7476 is a complete thermal monitor and 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 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
•
Dynamic T
MIN
, dynamic operating point, and associated
registers are no longer available on the ADT7476. The
following related registers are not available in the
ADT7476:
•
Calibration Control 1 and Calibration Control 2
(Register 0x36 and Register 0x37)
•
Operating Point (Register 0x33, Register 0x34, and
Register 0x35)
•
Previously, T
RANGE
defined the slope of the automatic fan
control algorithm. For the ADT7476, T
RANGE
now defines a
true temperature range.
•
For the ADT7476, acoustic filtering is now assigned to
temperature zones and not to fans. Smoothing times have
been increased for better acoustic performance.
•
For the ADT7476, temperature measurements are made
with two switching currents instead of three. SRC is not
available in the ADT7476.
•
For the ADT7476, high frequency PWM can now be
enabled/disabled on each PWM output individually.
•
For the ADT7476, THERM can now be enabled/disabled
on each temperature channel individually.
•
The ADT7476 does not support full shutdown mode.
•
The ADT7476 defaults to twos complement temperature
measurement mode.
•
Some pins have swapped/added functions.
•
The power-up routine for the ADT7476 is simplified.
Other minor changes in the ADT7476 include the following:
•
Vcore_low_enable has been reallocated to Bit 7 of
Configuration Register 1 (0x40).
•
Device ID register (0x3D) reads 0x76.
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