PRM48JH480X250A00 Datasheet, PDF (41/44 Pages) Vicor Corporation – Pin selectable operating mode

Line Dropout Operation
The PRM48JH480x250A00 is optimized for post PFC operation
where holdup capacitance is located on the 48 V bus.
The PRM48JH480x250A00 is capable of operating down as low as
30.0 V_IN for up to 200 ms in order to provide extended holdup
capacity during an AC line dropout.
During an AC line dropout, once the input voltage crosses 38.0 V, a
200 ms timer t_DROPOUT is enabled.
If the input recovers above the recovery threshold within 200 ms,
then the timer is disabled and normal operation resumes. Otherwise
if the input voltage fails to reach the recovery threshold, or if the
undervoltage lockout threshold is crossed, powertrain
shutdown is initiated.
Figure 43 illustrates 3 line dropout conditions.
a) The input recovers above the recovery threshold before t_DROPOUT
expires, and normal operation resumes
b) t_DROPOUT expires before the input reaches the recovery
threshold, and the powertrain shuts down
c) V_IN crosses the V_{IN_UVLO} threshold and the powertrain shuts down
During Line Dropout Operation, output current and power are
linearly de-rated to 75% between 38.0 V and 30.0 V as specified
in Figure 42.
PRM48JH480x250A00
Rated Power and Current vs. Line Voltage
120
100
80
60
Line Dropout Operation
200msec, 10% Duty
Sustained Operation
Cycle Max
40
20
0
25
30
35
40
45
50
55
60
PRM Input Voltage
Figure 42 — Line Dropout Derating
48V
38V
VIN_UVLO
INPUT
VOLTAGE
ENABLE
OUTPUT
VOLTAGE
(a)
Drop-out time < 200 ms
Figure 43 — Line Dropout Operation Timing Diagram
200ms
(b)
Drop-out time > 200 ms
(c)
Input Undervoltage
PRM^TM Regulator
Page 41 of 44
Rev 1.2
11/2015
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