CM4 App Note 260424 issue 2.1.docx
Document No. 260424
Page 4 of 29
2. Input Module Operation
Startup & Shut Down
The CM input module operates from a universal input voltage range and starts automatically upon application of adequate AC mains voltage
(>84Vrms). 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
≤2000 ms, t
2
≤400 ms, t
3
≤600 ms, t
4
≥15 ms, t
5
≥5ms (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.
Standby control
The unit may be completely shut down by shorting (<10
Ω) the terminals of J2. The unit will restart once the short is released.
The control uses transformer coupled pluses to detect the short and is fully isolated to 2xMOPP. The voltage present on J2 ranges from +3.3V to
-0.8V with a peak current of 15mA. In active mode, the control is pulsed every 1.3 ms while in standby mode the control is pulsed every 400 ms.
A signal MOSFET or switch may be used to activate this control. This shutdown will not generate the ACOK warning signal.
Programmable start-up state
The start-up and standby control logic can be inverted by shorting J11 with a jumper. The functionality is shown in the table below.
J11
J2
Operational mode
Comments
Open
Open
NORMAL
Default. Unit will start into NORMAL mode
Open
Closed
STANDBY
<1W power consumption
Closed
Open
STANDBY
Unit will start into STANDBY mode. <1W power consumption
Closed
Closed
NORMAL
J11 LOCATION
J2 LOCATION
- +
J11
J12
