AMC6821SDBQG4 Datasheet, PDF (22/56 Pages) Texas Instruments – Intelligent Temperature Monitor and PWM Fan Controller

AMC6821
SBAS386C – MAY 2006 – REVISED JULY 2007
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FAN CONTROL
THERM Pin and External Hardware Control
The THERM pin is a bi-directional I/O, as shown in Figure 22.
THERM Pin As An Output
As an open-drain output, the THERM pin is the indicator of temperature over the THERM limit. When the remote
temperature exceeds the Remote-THERM-Limit, or when the local temperature is greater than the
Local-THERM-Limit, the THERM pin goes low and remains low until the measured temperature falls 5°C below
the exceeded THERM limit.
Drive Fan at Full Speed
THERM-FAN-EN
L-THERM Bit
(Set to ‘1’ when the local temperature is
greater than the Local-THERM-Limit.)
Local temperature is less than (Local-THERM-Limit - 5°C)
R-THERM Bit
(Set to ‘1’ when the remote temperature is
greater than the Remote-THERM-Limit.)
Remote temperature is less than (Remote-THERM-Limit - 5°C)
Latch
Set
Output
Reset
Latch
Set
Output
Reset
THERM
THERM-IN bit
(Drive fan at full speed when THERM-IN = 1)
Figure 22. Structure of the THERM Pin
22
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