28 V Wide Maxi Family

Rev 2.8

vicorpower.com

Page 8 of 12

02/2016

800 927.9474

28 V Input

Module Enable / Disable

The module may be disabled by pulling PC below 2.3 V 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 2.

Primary Auxiliary Supply

At 5.7 V, PC can source up to 1.5 mA. In the example shown

in Figure 4, 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 3 and 5.

+IN

PC

PR

–IN

Disable

Disable = PC <2.3 V

Figure 2 — Module enable / disable.

Figure 4 — LED on-state indicator.

+IN

PC

PR

–IN

4 kΩ

"Module

Enabled"

+IN

PC

PR

–IN

Optocoupler

4 kΩ

Alarm

1.00V

+OUT

+S

SC

–S

–OUT

Comparator

+OUT

+S

SC

–S

– OUT

+IN

PC

PR

–IN

Input Undervoltage

2-20 ms typ.

f (VIN)

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

Overtemperature

Module Faults

1 Not applicable for 300 Vdc input family

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.

PRIMARY CONTROL - PC PIN