QM range App Note, document number 260283, rev 15
Page 7 of 48
AC Fail
An isolated opto-coupler transistor output. Pin 7 is the collector and pin 8 the emitter. This signal provides a
warning that the AC is not present (or out of range) and the outputs will be losing regulation after 5ms. The
transistor is “on” when the AC is good. It is recommended that the AC Fail is connected to the 5V standby 1
supply with a 5.1k
Ω series resistor to limit the current.
Option Code P5H
Standby
An isolated 5V 2A output and is always present provided AC is applied to the QM.
The Fan Fail signal
Provided by an internal FET which is referenced to pin 12 of the option connector. Pin 4 is the FET drain (+)
and pin 12 the source (-). This signal provides a warning that the QM fan has stopped or the fan speed is
slowing and should be replaced. The FET will be on when the fan is running less than 50% of the expected fan
speed for the ambient tempera
ture and “off” if the fan speed is above 50%. It is recommended that the Fan Fail
is connected to the 5V standby supply with a 5.1k
Ω series resistor to limit the current.
J5-1 5V Standby positive
J5-2 5V Standby negative
J5-3
J5-4 Fan Fail positive
J5-5
J5-6
J5-7
J5-8
J5-9
J5-10
J5-11
J5-12 Fan Fail negative (GND)
5.1k
Ω
Fan Fail Output
Low on Fail