CONTROL FUNCTIONS - SC PIN
Output Voltage Programming
The output voltage of the converter can be adjusted or
programmed via fixed resistors, potentiometers or voltage
DACs. See Figures 7 and 8.
+Out
+S
Error
Amp
1kΩ
0.033
µF
1.23V
+Out
+S
SC
–S
–Out
R
D
Trim Down
Load
Error
Amp
1kΩ
0.033
µF
1.23V
SC
–S
–Out
R
U
Trim Up
Load
R
D
(ohms) =
1,000 Vout
Vnom - Vout
R
U
(ohms) =
1,000
(Vout-1.23)
Vnom
1.23
(Vout-Vnom)
–1,000
Figure 7—Output
voltage trim down circuit.
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 –Sense pin.
Figure 8—Output
voltage trim up circuit.
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 +Sense pin.
3. Do not trim the converter above maximum trim range
(typically +10%) or the output over voltage
protection circuitry may be activated.
Trim resistor values calculated automatically:
On-line calculators for trim resistor values are available
on the vicor website at: vicorpower.com/tools.html.
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 also include design tips, applications
circuits, EMC suggestions, thermal design guidelines and
PDF data sheets for all available Vicor products.
Vicor Corp.
Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
V375B24C300A DC-DC Converter
Rev. 5.2
Page 5 of 8
Set your site on VICOR at www.vicorpower.com
VICOR [ VICOR CORPORATION ]
