PRD15 Datasheet, PDF (13/14 Pages) CUI INC – DC-DC CONVERTER

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CUI Inc │ SERIES: PRD15 │ DESCRIPTION: DC-DC CONVERTER
date 03/28/2016 │ page 13 of 14
APPLICATION NOTES
Output Voltage Trimming
The output voltage can be adjusted by using the trim pin and the use of either an external trimpot of the use of a single
fixed resistor (See Figures 3~5 below).Trimming resistors should have a low temperature coefficient (± 100 ppm/°C or
less) and be mounted close to the converter. For input voltage < 20 Vdc, PRD15-Q48-S5 can only be trimmed down. If
the trim function is not needed, leave the trim pin open.
Figure 3 Trim Adjustments Using
A Trimpot
Figure 4 Trim Adjustments To Decrease
Output Voltage Using A Fixed Resistor
Figure 5 Trim Adjustments To Increase
Output Voltage Using A Fixed Resistor
−VIN
+VOUT
−VIN
+VOUT
−VIN
+VOUT
ON/OFF
CONTROL
TRIM
75-22
TURNS
LOAD
ON/OFF
CONTROL
TRIM
RTRIM DOWN
LOAD
ON/OFF
CONTROL
TRIM
R TRIM UP
LOAD
+VIN
−VOUT
+VIN
−VOUT
+VIN
−VOUT
Rtrim - up =
A
Vo - Vo, nom
-B
Note: R_trim-up is the external resistor in Ω
R_trim-down is the external resistor in Ω
V_{O, nom} is the nominal output voltage
V_O is the desired output voltage
Vout
A
B
C
Rtrim
-
down
=
C(Vo -
Vo, nom
2.5)
- Vo
-
B
3.3 12775 2050 5110
5 12775 2050 5110
12 25000 5110 10000
15 25000 5110 10000
Remote On/Off Control
The DC-DC converter can be ordered with either positive or negative logic.See page 2 for enable/disable details for both
positive and negative logic options. Dynamic control of the On/Off function should be able to sink appropriate signal
current when brought low and withstand appropriate voltage when brought high.Be aware that there is a finite time in
milliseconds between the the time of On/Off control activation and stable, regulated output.This time will vary slightly
with output load type and current and input conditions.
Cautions when using the On/Off control:
1. To retain full output circuit isolation, control the On/Off from the input side only.
2. While it is possible to control the On/Off with external logic if you carefully observe the voltage levels, the
preferred circuit is either an open drain/open collector transistor, a switch, or a relay.
3. Do not apply voltages to the On/Off pin when there is no input power voltage, otherwise the converter may be
permanently damaged.
Figure 6. Driving The On/Off Control Pin
(Suggested Circuit)
ON/OFF CONTROL
+ Vcc
CONTROL
-VIN
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