Datasheet

PWM_OUT
2s 2s 2s
TACH
INT
FAN_FAULT
Full-Speed
Continuing
TACHFailure
StatusRegisterReadtoClearInterrupt
FourthTACHFailure
FifthTACH
Failure
ThirdTACHFailure
FAN-FAULT PIN
FAN-FAULT
+V
10kW
AMC6821
FanFailure
(belowminimumspeed
afterfifthspin-up)
PinisEnabled
(F AUL -ENbit=1)AN-F T
AMC6821-Q1
www.ti.com ...................................................................................................................................................................................................... SBAS475 – JUNE 2009
The SMBALERT pin continues to generate interrupts after the assertion of the FAN-FAULT pin because the tach
measurement continues even after a fan failure. Should the fan recover from the failure condition, the
FAN-FAULT pin signal is negated and the fan returns to normal operating speed. Figure 20 shows the operation
of a FANS interrupt.
INT is a Fan-Slow (FANS) Interrupt Through the SMBALERT Pin
Figure 20. Operation of the FAN-FAULT Pin with a Spin-Up Time = 2 Seconds
The FAN-FAULT pin is an open-drain output pin, as shown in Figure 21 . When the FAN-FAULT-EN bit of
Configuration Register 1 is cleared ('0'), this pin is disabled and is always in a high-impedance status. When
FAN-FAULT-EN = 1, the pin is enabled and the status indicates a fan-failure. The pin asserts low when a fan
failure occurs. FAN-FAULT is negated when the fan returns to normal speed.
Figure 21. FAN-FAULT Pin
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