AMC6821-Q1 Datasheet, PDF (15/54 Pages) Texas Instruments – INTELLIGENT TEMPERATURE MONITOR AND PWM FAN CONTROLLER

AMC6821-Q1
www.ti.com ...................................................................................................................................................................................................... SBAS475 – JUNE 2009
4. THERM Limit: This limit is an additional fail-safe threshold. When the local or remote temperature is equal to
or above this limit, the corresponding L-THERM or R-THERM bit is set ('1'), and the THERM pin is asserted
low, which can be used to throttle the CPU clock. Furthermore, the THERM interrupt is generated on the
SMBALERT pin if enabled (THERMOVIE = 1). Reading Status Register 1 clears the R-THERM and
L-THERM bits. Once cleared, these bits are not reasserted until the temperature falls 5°C below the THERM
limit, even if the THERM condition persists. If the THERM-FAN-EN bit of Configuration Register 3 is set ('1'),
L-THERM = 1 or R-THERM = 1 forces the fan to run at full speed. When THERM-FAN-EN = 0, the status of
the L-THERM and R-THERM bits do not affect the fan speed directly. Note that the THERM limit can be
lower or higher than other temperature limits. For example, if the THERM limit is lower than the PSV
temperature limit, then the CPU clock can be throttled while the cooling fan is off.
Local-High-Temp-Limit
Local Temperature
Local-Low-Temp-Limit
LTH
LTO
LTL
LTOIE
LTO Interrupt
SMBALERT Pin Low
Remote-High-Temp-Limit
Remote Temperature
Remote-Low-Temp-Limit
Local-Critical-Temp
Local Temperature
RTH
RTL
RTO
RTOIE
LTC Bit in Status Register 2
RTO Interrupt
SMBALERT Pin Low
OVR Pin Low
SMBALERT Pin Low
Remote-Critical-Temp
Remote Temperature
RTC Bit in Status Register 2
OVR Pin Low
SMBALERT Pin Low
Active Control Temperature
PSV-Temp
LPSV Bit in Status Register 2
PSVIE
PSV Interrupt
SMBALERT Pin Low
L-THERM Limit
Local Temperature
THERM-FAN-EN
L-THERM Bit in Status Register 2
THERMOVIE
Assert THERM Pin Low
Force Fan to Full Speed
Local Therm Interrupt
SMBALERT Pin Low
R-THERM Limit
Assert THERM Pin Low
Remote Temperature
THERM-FAN-EN
R-THERM Bit in Status Register 1
THERMOVIE
Force Fan to Full Speed
Remote Therm Interrupt
SMBALERT Pin Low
Figure 14. Temperature Out-of-Range Detection
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