AMC6821 Datasheet, PDF (18/47 Pages) Burr-Brown (TI) – Analog Monitor and Control Circuit

AMC6821
SBAS386A – MAY 2006 – REVISED MAY 2006
www.ti.com
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 11 shows the operation
of a FANS interrupt.
PWM_OUT
2s
2s
2s
Full-Speed
TACH/AIN
INT
FAN_FAULT
Third TACH Failure
Fourth TACH Failure
Status Register Read to Clear Interrupt
Fifth TACH
Failure
Continuing
TACH Failure
Figure 11. Operation of the FAN-FAULT Pin with a Spin-Up Time = 2 Seconds
(INT is a Fan-Slow (FANS) Interrupt Through the SMBALERT Pin)
FAN-FAULT PIN
The FAN-FAULT pin is an open-drain output pin, as shown in Figure 12. When the FAN-FAULT-EN bit of
Configuration Register 1 is cleared ('1'), 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.
+V
Fan Failure
(below minimum speed
after fifth spin-up)
AMC6821
FAN-FAULT
10kW
Pin is Enabled
(FAN-FAULT-EN bit = 1)
Figure 12. FAN-FAULT Pin
18
Submit Documentation Feedback