CONTROL FUNCTIONS - PC PIN
Module Enable/Disable
The module may be disabled by pulling PC below 2.3V with
respect to the –Input. This may be done with an open collector
transistor, relay, or optocoupler. Multiple converters may be
disabled with a single transistor or relay either directly or via
“OR’ing” diodes. See Figure 1.
Primary Auxiliary Supply
At 5.7V, PC can source up to 1.5mA. In the example shown in
Figure 3, PC powers a module enabled LED.
Module Alarm
The module contains “watchdog” circuitry which monitors
input voltage, operating temperature and internal operating
parameters. In the event that any of these parameters are
outside of their allowable operating range, the module will shut
down and PC will go low. PC will periodically go high and the
module will check to see if the fault (as an example,
overtemperature) has cleared. If the fault has not been cleared,
PC will go low again and the cycle will restart. The SC pin will
go low in the event of a fault and return to its normal state after
the fault has been cleared. See Figures 2 and 4.
+In
PC
+In
SW1
Auto
Restart
2-20ms typ.
f (VIN)
Input Undervoltage
Input Overvoltage
Overtemperature
Module Faults
50Ω
SW2
SW3
1K
+Out
+S
SC
–S
PC
SW1, 2, & 3
shown in
"Fault" position
Disable
PR
–In
PR
–In
5.7Vdc
(0-3mA)
1.23
Vdc
6K
–Out
Disable = PC <2.3V
Figure 1—Module
enable/disable.
Figure 2—PC/SC
module alarm logic.
+In
Fault
PC
40µs typ.
5.7V
PC
"Module
Enabled"
4kΩ
PR
–In
SC
1.23V
2-20ms typ.
Figure 3—LED
on-state indicator.
Figure 4—PC/SC
module alarm timing.
Optocoupler
+In
PC
4kΩ
PR
–In
+Out
+S
SC
–S
–Out
1.00V
Alarm
Figure 5—Isolated
on-state indicator.
Vicor Corp.
Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
Figure 6—Secondary
side on-state indicator.
V300A3V3C264A DC-DC Converter
Rev. 5.2
Page 4 of 8
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