Power Integrations

5245 Hellyer Avenue, San Jose, CA 95138 USA.

Tel: +1 408 414 9200 Fax: +1 408 414 9201

www.powerint.com

Design Example Report

Title

10 W Power Supply using DPA423P

Specification

Input: 37-57 VDC

Output: 3.3V/2.0A, 5V/200mA, 12V/200mA

Application

VoIP phone

Author

Power Integrations Applications Department

Document

Number

DER-96

Date

September 12, 2005

Revision

1.0

Summary and Features

This document is an engineering prototype report describing a VoIP power supply

utilizing DPA423P.

• Eliminates LM78xx linear-regulators on 5 V

• Low-cost 12 V linear-reg. with short circuit protection provided by main supply

• High Efficiency (> 70% at 48 VDC)

• Low EMI signature (both radiated and conducted emissions)

• Low Parts Count

• Built-in input short circuit protection on all outputs

• Carefully designed for low EMI

The products and applications illustrated herein (including circuits external to the products and transformer

construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign

patent applications assigned to Power Integrations. A complete list of Power Integrations’ patents may be found at

www.powerint.com.