DER-34

13W Integrated Digital TV PSU

April 1, 2004

Page 3 of 19

Power Integrations

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1

Introduction

This report describes a multiple output power supply for an integrated digital TV

application. The design uses the advanced integrated features of TOP242P to give a low

cost, minimal component count design.

The report includes a full schematic, bill of materials and transformer design information.

In addition, basic measurements on the prototype unit shown in Figure 1 have been

given.

Figure 1 - 13W IdTV Power Supply Prototype

Measurements include full power efficiency, full power line regulation and output ripple

measurements. When accurate min/max loads and loading combinations are known,

cross-regulation measurements will be taken. Initial conducted EMI measurements have

also been taken both with the output floating and the output grounded to protective Earth

(i.e. chassis).

For the prototype constructed here, only one LC post filter was used on the 5V output

and the current on the 5VA and 5VD circuitry was combined to a single rail. The

proposed schematic splits the 5V rail out with two LC post filters to increase the

separation between 5VA and 5VD outputs.