Connecting the demo board

AN1246

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Connecting the demo board

This demo board has two connectors. Connect a DC voltage source capable of delivering up

to 400 volts DC to connector J1. Be sure to connect the positive source to the + terminal of

J1 and the negative to the terminal before turning on the input power. The minimum voltage

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Layout considerations

Some simple rules to improve performance and minimize noise should be followed:

1.

Minimize power loops. The switched power current paths inner loop area must be as

small as possible. This can be accomplished by careful layout of the printed circuit

board and the use of surface mount components. This avoids radiated and conducted

EMI noise, and improves the efficiency by eliminating parasitic inductance, thus

reducing or eliminating the need for snubbers and EMI filtering.

2.

Use separate tracks for low level signal and power traces carrying fast switching pulses.

This can be seen on the VIPer20ADIP-E pin 3 on the printed circuit lay out. When

signal paths share the same trace as a power path, instabilities may result. The

compensation components, CS6, RS3, and CS4 are on a separate trace connected

directly to the source of the device.

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Burst mode

When the output current is too low, the burst mode operation takes over automatically. This

As can be seen, there is one pulse out of ten pulses to reduce power consumption. The

output ripple is negligible.