Output Voltage Programming

The output voltage of the converter can be adjusted or

programmed via fixed resistors, potentiometers or voltage

DACs. See Figures 7 & 8.

Vicor Corporation Tel: 800-735-6200 Fax: 978-475-6715

Data Sheet: V24C28C100A DC-DC Converter Date: 11-00 Rev. 2

Page 5 of 8

CONTROL FUNCTIONS - SC PIN

Figure 8—Output voltage trim up circuit.

Figure 7—Output voltage trim down circuit.

1,000 (Vout-1.23) Vnom

- 1,000

1.23 (Vout-Vnom)

1,000 Vout

Vnom - Vout

Trim Up

Load

Error

Amp

1k

Ω

1.23V

0.033

µF

+Out

SC

–Out

Load

Trim Down

Error

Amp

1k

Ω

1.23V

0.033

µF

+Out

SC

–Out

Trim Down

1. This converter is not a constant power device – it has a

constant current limit. Hence, available output power is

reduced by the same percentage that output voltage is

trimmed down. Do not exceed maximum rated output current.

2. The trim down resistor must be connected to the –Out pin.

Trim Up

1. The converter is rated for a maximum delivered power. To ensure

that maximum rated power is not exceeded, reduce maximum

output current by the same percentage increase in output voltage.

2. The trim up resistor must be connected to the +Out pin.

3. Do not trim the converter above maximum trim range

(typically +10%) or the output over voltage

protection circuitry may be activated.

Trim values calculated automatically:

Resistor trim calculators are available on Vicor’s

web site at URL: www.vicr.com/tools.html

or by requesting a copy of Vicor’s

Applications Manual on a CD ROM.

Resistor values can be calculated for fixed

trim up, fixed trim down and for variable

trim up or down cases for both 1st and

2nd Generation DC-DC converters.

In addition to trimming information, the

web site and the applications manual on

CD ROM also include design tips,

applications circuits, EMC suggestions,

thermal design guidelines and PDF data

sheets for all available Vicor products.

Set your site on VICOR at www.vicr.com