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AN1657

APPLICATION NOTE

February 2003

Design Specification

The typical electrical specification of an SMPS of a 17" CRT monitor for PC is summarized in table 1. Two

goals concerning the off-mode consumption of the SMPS have been set: the first one is to meet the

more ambitious goal is to comply with IEA's "1W initiative" as well as to be eligible for GEEA label. Both

voluntary standards require to achieve a power consumption below 1W.

Table 1. 90W SMPS for CRT monitor: electrical specification

QR approach and the L6565

The SMPS will be realized with a Quasi-resonant (QR) flyback converter based on the L6565, a control

IC specifically designed to handle such kind of converters. Referring to [1] and [2] for a detailed description

of the device and the topology, it is here worthwhile reminding that QR operation implies that the trans-

Input Voltage Range (Vin)

88 to 264 Vac

50/60 Hz

Maximum Output Power (Pout)

92 W

Outputs

Horizontal Deflection

Vout = 200V

± 3%

Iout = 0.33A

Full load ripple = 1%

Video Amplifier

Vout = 80V

± 5%

Iout = 0.13A

Full load ripple = 1%

Vertical Deflection

Vout = ± 15V

± 10%

Iout = 0.33 A

Full load ripple = 1%

Heater

Vout = 6.5V

± 10%

Iout = 0.6A

Full load ripple = 2%

Micro

Vout = 5.0V

± 2%

Iout = 0.05A

Full load ripple < 1%

25 kHz

Target Efficiency (Vin =88 to 264 Vac, full load) (

η)> 85%

Suspend-Mode Input Power (Vin = 88 to 264 Vac)

<15 W

OFF-Mode Input Power (@Pout = 125 mW on 5V output, Vin = 88 to 264 Vac)

< 1W (IEA, GEEA)

by Claudio Adragna

SMPS FOR CRT MONITORS WITH THE L6565

This note shows and discusses a couple of designs of a 90W wide-range-mains SMPS for CRT monitor

based on the QR controller L6565. The first design refers to a low-cost SMPS that meets current Ener-

first one so as to be compliant with IEA's "1W initiative". Both have been realized and tested on the

bench. The result of their evaluation is presented along with some significant waveforms.