RBE-12 Datasheet, PDF (13/15 Pages) Murata Manufacturing Co., Ltd. – Eighth-Brick 240-Watt Isolated DC/DC Converters

Output OVP (Output Clamped)
The RBE-12/20-D48 module incorporates circuitry to protect the output/load
(Output OVP, Over Voltage Protection) by effectively clamping the output volt-
age to a maximum of 13.5V under certain fault conditions. The initial output
voltage is set at the factory for an accuracy of ±1.5%, and is regulated over
line load and temperature using a closed loop feedback system. In the event
of a failure that causes the module to operate open loop (failure in the control
loop), the output voltage will be determined by the input voltage/duty cycle of
the voltage conversion (Pulse Width Modulation) circuit. For example, when
the input voltage is at 36V, the duty cycle is D1; when the input voltage is at
75V, the maximum duty cycle is D1/2; this change in duty cycle compensates
Vout for Vin changes. As Vin continues to increase above 75V the voltage at
Vout is clamped because maximum duty cycle has been reached. The output
voltage is always proportional to Vin*Duty in a buck derived topology. Figure 4
is the test waveform for the RBE-12/20-D48 module when its feedback loop is
open, simulating a loop failure. Channel 1 is the input voltage and Channel 2 it
the output voltage. When the input voltage climbs from 48Vdc to 100Vdc, the
output voltage remains stable.
RBE-12/20-D48 Series
Eighth-Brick 240-Watt Isolated DC/DC Converters
Figure 4. Test Waveform with Feedback Loop Open
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MDC_RBE-12-20-D48.A02Δ Page 13 of 15