AN2544 Datasheet, PDF (1/17 Pages) STMicroelectronics – Designing a low cost power supply using

AN2544
Application note
Designing a low cost power supply using a
VIPer12/22A-E in a buck configuration
Introduction
Many appliances today use nonisolated power supply to furnish low output power required
to run a micro, LED display, and a few relays or AC switches. This type of power supply has
a single rectifier so as to reference the neutral to output ground in order to fire TRIACs or AC
switches. This article describes the use of the VIPer12A-E and the VIPer22A-E which are
pin-for-pin compatible and can supply power for many applications. This paper provides an
off-line, nonisolated power supply evaluation board based on the VIPer12/22A-E. Four
different examples are covered. The VIPer12A-E is used for 12 V at 200 mA and 16 V at 200
mA. The VIPer22A-E is used for 12 V at 350 mA and 16 V at 350 mA. The same board can
be used for any output voltage from 10 V to 35 V. For outputs less than 16 V, D6 and C4 are
populated and W1 is omitted. For outputs greater than 16 V, D6 and C4 are omitted and W1
is populated. For more design detail, see AN1357 "VIPower: low cost power sullies using
the VIPer12A-E in nonisolated application." The objective of this application note is to
familiarize the end user with this reference design and to quickly modify it for different
voltage output. This design gives:
■ Lowest possible component count
■ Integrated thermal overload protection
■ About 200 mW at no-load consumption
■ Efficiency measured between 70% to 80% at full load
■ Integrated Short circuit protection
Figure 1. Evaluation board (STEVAL-ISA035V1)
Table 1. Operating conditions for the four samples
Board version (with changes)
Output voltage and current
Input voltage range
Input voltage frequency range
85 V_ac to 264 V_ac
50/60 Hz
Output version 1 VIPer22ADIP-E
12 V at 350 mA 4.2 W
Output version 2
Output version 3
VIPer12ADIP-E
VIPer22ADIP-E
12 V at 200 mA 2.4 W
16 V at 350 mA 5.6 W
Output version 4 VIPer12ADIP-E
16 V at 200 mA 3.2 W
November 2007
Rev 4
1/17
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