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CUI Inc

│ SERIES: PQA50-T │ DESCRIPTION: DC-DC CONVERTER

date 07/15/2015

│ page 6 of 7

1. Requirement on output load

Toensurethismodulecanoperateefficientlyandreliably,theminimumoutputloadcannotbelessthan5%ofthefullloadduring

operation. If the actual output power is small, please connect a resistor at the output end in parallel to increase the load.

2. Recommended circuit

This series has been tested according to the following recommended testing circuit before leaving the factory. This series should be

testedunderload(seeFigure3).Ifyouwanttofurtherdecreasetheinput/outputripple,youcanincreasecapacitanceproperlyor

choose capacitors with low ESR (see table 3). However, the capacitance must not exceed the maximum capacitive load or a start-up

problem might arise (see table 4).

3. Output Voltage Trimming

Leave open if not used.

FormulaforTrimResistor

Application Circuit for Trim Pin

(part in broken line is the interior of models)

Note: Value for R1, R2, R3, and Vref (see Table 5)

R

a:User-definedparameter,noactualmeanings

Vo': The trim up/down voltage

up:

a=

Vref

Vo’-Vref

R=

R-a

2

down:

a=

Vref

Vo’-Vref

R=

T

T

R-a

1

APPLICATION NOTES

Figure 3

Table 3

Table 4

Table 5

Figure 4

Vout

(Vdc)

Cin

(µF)

Cout

(µF)

3.3

100

220

5

100

220

12

100

100

15

100

100

24

100

47

Notes:

1. Minimum load shouldn't be less than 5%, otherwise ripple may increase dramatically. Operation under minimum load will not damage the converter, however, they may

notmeetallspecificationslisted.

2. Maximum capacitive load is tested at input voltage range and full load.

3.AllspecificationsaremeasuredatTa=25°C,humidity<75%,nominalinputvoltageandratedoutputloadunlessotherwisespecified.

+Vo

0V

Trim

0V

Trim

+Vo

Trim up

Trim down

DC

DC

Vin

GND

+Vout

0V

Cin

Vout

(Vdc)

Max.

Capacitive Load

(μF)

3.3

27000

5

18900

12

3700

15

2000

24

1000

Vout

(Vdc)

R1

(kΩ)

R2

(kΩ)

R3

(kΩ)

Vref

(V)

3.3

4.788

2.87

15

1.24

5

2.87

2.87

12.1

2.5

12

11

2.87

22

2.5

15

15

3

22

2.5

24

20

2.308

15

2.5

For more information, please visit the product page.