6
Input module operation
Start-up and shut-down
The RCB600 and MCB600 input modules operate from a universal input voltage range and start automatically upon application
of adequate AC mains voltage (>84 V
RMS
). After a short delay, the global “+5V bias” supply starts and the “ACOK” signal
goes high to indicate that the mains voltage is present and input stage is operating correctly. Once the “ACOK” signal is high,
the output modules turn on and deliver power to the application loads. The “Power Good” signals will indicate that the output
voltages are within specification. The diagram below shows the normal start-up/shut-down sequence and gives typical timings.
Typical timing values:
t
1
= 300 ms, t
2
= 50 ms, t
3
=
25 ms, t
4
= 15 ms, t
5
= 5 ms (minimum), t
6
= 100 ms
When the AC mains voltage is removed, the internal hold-up capacitors will supply power to the load for typically 20 ms (t
4
+t
5
)
at maximum power. The “ACOK” signal will go low at least 5 ms before the output voltages fall below the power good
threshold level. This allows the application to prepare for the impending loss of power. The “+5V bias” supply will remain on
for typically 100 ms, after the output modules have turned off.
Hold-up
For short line disturbances (<20 ms), the output voltages will not be affected*. However, the “ACOK” signal may still go low to
warn that there is an impending loss of output power. The “ACOK” signal will return to the high state once the unit has
recovered from the disturbance.
*
Outputs that are adjusted above the hold-up voltage as detailed in their respective datasheets, may experience a dip in voltage but never
below the hold-up voltage specified.
Idle power
The idle power of the RCB/MCB PSU is extremely low when compared to similar power supplies.
With the output modules enabled the unit typically only requires 28 W with no output load. To reduce the idle power further
the outputs can be disabled using the global inhibit (GINH) pin. With the outputs disabled the unit typically requires less than
21 W.
Over temperature protection (OTP)
The input module is protected from excessive temperatures by means of various internal sensors. If temperature thresholds
are exceeded the entire unit may latch off, with no “ACOK” warning. To re-enable the unit, the AC mains must be disconnected
for approximately 2 minutes.
I
NPUT
M
ODULE
O
PERATION
