page

date

DESCRIPTION: half-brick dc-dc converter

8 of 9

08/2009

20050

phone

phone 503.612.2300 fax

www.v-infinity.com

fax 503.612.2383

PART NUMBER: VHB150W

14. OUTPUT SERIES CONNECTIONS

Two or more converters can be connected in series to obtain a higher output voltage. To prevent output reverse biasing each other in

case of a short, add a Schottky diode on each output in reverse polarity, as shown in the diagram. In the event of a short, the con-

verters will forward-bias the diodes and the output reversal will be limited to one diode drop (about 0.5V) only, so as not to damage

the converters. The forward current will cause each converter to go into short-circuit protection.

For proper diode selection, make

sure that: 1) the diodes voltage rating is higher than each converter output; 2) the rated diode current can carry the short-circuit cur-

rent; 3) the diodes do not overheat before the short is removed.

15. REMOTE OUTPUT ON/OFF CONTROL

The converter output can be enabled or disabled through the On/Off pin. The control logic is shown in this table. A common control

circuit is shown below. The standard version defaults to positive logic. For negative logic, indicate the selection when ordering.

16. ISOLATION

The input and output of the converter are electrically isolated. If needed, an output terminal can be connected to an input terminal,

resulting in the converter non-isolated.

Logic Table

Negative logic

Positive logic

SW Closed (V

<0.8 V) Output on

Output off

SW Open (V

>2.4 V)

Output off

Output on

REM

REM

SW

High signal here

disable output

-Vin (pin 4)

REM (pin 2)

REM

-Vin

SW

REM

-Vin

-Vo

+Vo

FIGURE 8. REMOTE ON/OFF CONTROL

FIGURE 9. REMOTE ON/OFF CONTROL

WITH TRANSISTOR SWITCH

+Vin

-Vin

+Vo

-Vo

+Vin

-Vin

+Vo

-Vo

FIGURE 7. OUTPUT

SERIES CONNECTIONS