28 V Wide Micro Family

Rev 2.0

vicorpower.com

Page 7 of 11

12/2014

800 927.9474

28 V Wide Input

Module Enable/Disable

The module may be disabled by pulling PC to 0 V (2.3 V

max) with respect to the –Input. This may be done with an

open collector transistor, relay, or optocoupler. Converters

may be disabled with a single transistor or relay either directly

or via “OR’ing” diodes for 2 or more converters. See Figure 2.

Primary Auxiliary Supply

During normal operation only, the PC Pin can source 5.7 V @

1.5 mA. In the example shown in Figure 4, PC powers a mod-

ule 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,

Input Undervoltage) 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 nor-

mal state after the fault has been cleared. See Figures 3 and 5.

PRIMARY CONTROL - PC PIN

Disable

Disable = PC < 2.3 V

+IN

PC

PR

–IN

Figure 2 — Module enable/disable.

Figure 4 — LED on-state indicator.

4 k

Ω

"Module

Enabled"

+IN

PC

PR

–IN

Optocoupler

+IN

PC

PR

–IN

4 k

Alarm

1.00 V

+OUT

SC

–OUT

Comparator

Input Undervoltage

Input Overvoltage [a]

Over Temperature

Module Faults

2-20 ms typ.

Auto

Restart

5.7 Vdc

(0-3 mA)

50

Ω

SW2

SW3

1.23

Vdc

6 K

1 K

SW1

SW1, 2, & 3 shown

in "Fault" position

+OUT

SC

–OUT

+IN

PC

PR

–IN

1 M

Figure 3 — PC/SC module alarm logic.

Figure 6 —Isolated on-state indicator.

2-20 ms typ.

Fault

SC

PC

1.23 V

5.7 V

40 µs typ.

Figure 5 —PC/SC module alarm timing.

Figure 7 — Secondary side on-state indicator.