AN1842 Datasheet, PDF (1/17 Pages) STMicroelectronics – 60W WIDE-RANGE POWER SUPPLY

AN1842
APPLICATION NOTE
60W WIDE-RANGE POWER SUPPLY
FOR LCD MONITOR OR TV, USING THE L5991
by Claudio Spini
This document describes a reference design for a 60W Switch Mode Power Supply dedicated to LCD
TV sets or monitors. The board accepts full range input voltage (90 to 265Vrms) and delivers 5V and
12V. It has good efficiency and very good standby performance, able to meet the most stringent
standby rules.
Introduction
The LCD monitors and TVs are growing very fast, so to support this kind of applications, a dedicated ref-
erence design has been developed, taking into account all the requirements that are needed.
The proposed reference design can supply an LCD monitor or an LCD-TV as well, up to 22" panels, to-
gether with multimedia functions like audio. The SMPS accepts a full range input voltage and delivers 2
output voltages, a 5V dedicated to the scaler and µP, and a 12V dedicated to the backlight and audio. The
required standby power consumption is 0.8W at 230Vac, in order to satisfy the worldwide power saving
rules. The circuit is also fully protected against faults like output short circuit or over voltage. The market
cost pressure has requested a design approach with particular attention to the solution cost. The board
technology used is the standard thru-hole, but it can be changed very easily in SMT because most of com-
ponents are available also in this technology. The circuit has been tested deeply in all the most salient
aspects with positive results and it has been integrated with a 22" LCD-TV application without showing
any problem.
Main characteristics
INPUT VOLTAGE:
OUTPUT VOLTAGES:
STANDBY
FAULT PROTECTIONS:
Safety&EMC:
PCB TYPE & SIZE:
90 ÷ 265 Vrms - 45-66 Hz
5.1V±2% - @2A Dedicated to panel and digital circuitry for scaling
12V±10% - @4A Dedicated to backlight lamp inverters, audio and SCART
Input power less than 0.8W @230Vac, delivering 30mA on 5.1V
Short circuit on each output with auto-restart at short removal, Open loop
Safety: Acc. to EN60950, creepage and clearance minimum distance 6.4mm
EMC: According to EN50022 Class-B
Cu Single Side 70 µm, CEM-1, 180 x 89 mm
January 2004
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