AN1657 Datasheet, PDF (1/9 Pages) STMicroelectronics – SMPS FOR CRT MONITORS WITH THE L6565

AN1657
APPLICATION NOTE
SMPS FOR CRT MONITORS WITH THE L6565
by Claudio Adragna
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-
gyStar^® requirements on OFF-mode consumption (Pin<2W). The second design is an evolution of the
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.
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
present EnergyStar^® requirements, which envisage less than 2W absorbed from the mains; the second
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
Input Voltage Range (Vin)
Mains Frequency (f_L)
Maximum Output Power (Pout)
Horizontal Deflection
Video Amplifier
Outputs
Vertical Deflection
Heater
Micro
Minimum Switching Frequency in Normal Mode (f_MIN, @ Vin = 100 V_DC, full load)
Target Efficiency (Vin =88 to 264 Vac, full load) (η)
Suspend-Mode Input Power (Vin = 88 to 264 Vac)
OFF-Mode Input Power (@Pout = 125 mW on 5V output, Vin = 88 to 264 Vac)
88 to 264 Vac
50/60 Hz
92 W
Vout = 200V ± 3%
Iout = 0.33A
Full load ripple = 1%
Vout = 80V ± 5%
Iout = 0.13A
Full load ripple = 1%
Vout = ± 15V ± 10%
Iout = 0.33 A
Full load ripple = 1%
Vout = 6.5V ± 10%
Iout = 0.6A
Full load ripple = 2%
Vout = 5.0V ± 2%
Iout = 0.05A
Full load ripple < 1%
25 kHz
> 85%
<15 W
< 2W (EnergyStar^®)
< 1W (IEA, GEEA)
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-
February 2003
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