Datasheet Summary
DESIGN SHOWCASE
Supervisor IC indicates fan failure
The brushless DC fans found in many types of equipment can be crucial to the performance and longevity of that equipment. A quick indication of fan failure, moreover, can be essential in preventing major damage. Among the many approaches for identifying and indicating stalled fans, the circuit of Figure 1 is very simple and reliable. The fan’s tachometer output connects to the watchdog input of a µP supervisor (U1). The LED remains off during normal operation. If the tachometer does not change state within a watchdog timeout period, U1 lights the LED by asserting its reset output. As a result, the LED pulses on and off as the supervisor...