cui.com

CUI Inc

│ SERIES: VGDS2-SIP │ DESCRIPTION: DC-DC CONVERTER

date

09/10/2012 │ page 4 of 5

APPLICATION NOTES

1.

Requirement on output load

To ensure that this module can operate efficiently and reliably, a minimum load is specified in addition to a maximum load. During

operation, make sure that the specified range of input voltage is not exceeded and that the minimum output load is not less than 10%

of the full load. This product should never be operated under no load. If the output of the power supply is small, please connect a

resistor with proper resistance at the output end in parallel to increase the load.

2.

Recommended testing and application circuit

An output capacitor is needed to meet output ripple requirements as shown in Table 2. Output capacitance may be increased for ad-

ditional filtering, but should not exeed 10μF or expanded to an LC network as in Figure 1.

It should also be noted that the inductance and the frequency of the “LC” filtering network should be staggered with the dc-dc fre-

quency to avoid mutual interference. However, the capacitance of the output filter capacitor must be correct. If the capacitance is too

large then a startup problem may arise. For every channel of output, provided that safe and reliable operation is ensured, the recom-

mended capacitance of its filter capacitor should be as seen in Table 1.

It is not recommended to connect any external capacitor in the application field with less than a 0.5 W output.

3.

Output voltage regulation and over-voltage protection circuit

The simplest device for output voltage regulation, over-voltage and over-current protection is a linear voltage regulator with overheat

protection that is connected to the output end in series. (Figure 2)

4.

Overload protection

Under normal operating conditions, the output circuit of these dc-dc converters has no protection against overload. The simplest

method is to connect a self-recovery fuse in series at the input end or add a circuit breaker to the circuit.

Vin

GND

+Vo

0V

DC

Cin

L

L

DC

L Cout

Cout

-Vo

Figure 1

Vin

(Vdc)

Cin

(μF)

Dual Vout

(Vdc)

Cout

(μF)

5

10

±5

4.7

12

4.7

±9

2.2

--

--

±12

1.0

24

2.2

±15

0.47

Table 1

Vin

GND

0V

+Vo

DC DC

-Vo

REG

REG

REG

Figure 2