AV45C datasheet(20/25 Pages) ASTEC

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Output Over-Current Protection

AV45C quarter-brick series DC/DC converters

feature foldback current limiting as part of their

Overcurrent Protection (OCP) circuits. When

output current exceeds 110 to 140% of rated

current, such as during a short circuit condition,

the output will shutdown immediately, and can

tolerate short circuit conditions indefinitely.

When the overcurrent condition is removed, the

converter will automatically restart.

Output Filters

When the load is sensitive to ripple and noise,

an output filter can be added to minimize the

effects. A simple output filter to reduce output

ripple and noise can be made by connecting a

capacitor across the output as shown in Figure

15. The recommended value for the output

capacitor C1 is 2200

µF/10V (refer to page 3).

Extra care should be taken when long leads or

traces are used to provide power to the load.

Long lead lengths increase the chance for

noise to appear on the lines. Under these con-

ditions C2 can be added across the load as

shown in Figure 16. The recommended compo-

nent for C2 is 2200

µF/10V capacitor and con-

necting a 0.1

µF ceramic capacitor C1 in paral-

lel generally.

Decoupling

Noise on the power distribution system is not

always created by the converter. High speed

analog or digital loads with dynamic power

demands can cause noise to cross the power

inductor back onto the input lines. Noise can be

reduced by decoupling the load. In most cases,

connecting a 10

µF tantalum capacitor in paral-

lel with a 0.1

µF ceramic capacitor across the

load will decouple it. The capacitors should be

connected as close to the load as possible.

Ground Loops

Ground loops occur when different circuits are

given multiple paths to common or earth

ground, as shown in Figure 17. Multiple ground

points can slightly different potential and cause

current flow through the circuit from one point to

another. This can result in additional noise in all

the circuits. To eliminate the problem, circuits

should be designed with a single ground con-

nection as shown in Figure 18.

+Vout

-Vout

Load

Fig.16 Output Ripple Filter For a Distant

Load

+Vout

-Vout

Load

Fig.15 Output Ripple Filter

+Vout

-Vout

Load

RLine

Ground

Loop

Fig.17 Ground Loops

Fig.18 Single Point Ground

+Vout

-Vout

Load

RLine

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