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Maxim > Design Support > Technical Documents > Application Notes > Power-Supply Circuits > APP 819
Keywords: isolated power supply, supplies, telecom datacom applications, telecom buck flyback
converters, 50W, high frequency, forward converter, DC-DC converter, isolated supply, design software,
current mode
APPLICATION NOTE 819
Isolated Power Supply Is Suitable For
Telecom/Datacom Applications
Sep 20, 2002
Abstract: A 50W switching supply suitable for telecom applications is described. The supply, a high-
frequency forward converter, provides an isolated 5V @ 10A with 1% line and load regulation. A buck
converter topology is selected after considering flyback and buck converters. The MAX5003 control IC is
selected; its features and circuit are described. Important waveforms are shown and discussed; the power
transformer is detailed; input, output, and feedback circuits are discussed. Performance is detailed and
preferred PCB layout is provided.
Also see:
MAX5003 QuickView Data Sheet
MAX5003-50WEVKIT
MAX5003EVKIT
Design and simulate isolated power supplies with free MAX5003 Isolated Power Supply Design
Software.
This 50W, isolated power-supply design can be used to replace purchased supplies with minimal
additional engineering effort. The advantages of such an approach also include the accommodation of
custom footprint and substantially lower cost.
The Challenge
Power supplies are often an afterthought. Purchased power-supply "bricks" are a quick solution, but with
significant disadvantages, such as size, heat-sink and airflow requirements, long lead times, limited
configurations, and higher overall costs. An in-house design usually fits product requirements better, but
may not seem possible without a dedicated group of power-supply design engineers.
"Off-the-Shelf" Design
A few semiconductor companies are providing reference designs that can greatly streamline power-
supply design and bring custom supply designs within reach. An "off-the-shelf design" makes it possible
to quickly produce a supply that is smaller and simpler to integrate, performs better, and delivers much
lower cost and superior time-to-market.
Telecom/Datacom/Server Power Supplies
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