A5219 Datasheet, PDF (1/1 Pages) List of Unclassifed Manufacturers – Supervisor IC indicates fan failure

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
goes through its watchdog/reset cycle. The LED in
this example has a 200ms on-time and flashes with a
period of 1.6s, which is suitable for most purposes.
A similar article appeared in the November, 2003
issue of EET.
+5V
D1 _R2
300Ω ₁
RES
2
GND
3
MR
U1
MAX6316
5
VCC
4
WDI
R1
20kΩ
TACH
Figure 1. The MAX6316 µP supervisor monitors a fan’s tachometer output.
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