EVL6566B-65W-QR Datasheet, PDF (1/5 Pages) STMicroelectronics – 19 V - 65 W quasi resonant flyback adapter board

EVL6566B-65W-QR
19 V - 65 W quasi resonant flyback adapter board
Data brief
Features
■ Universal input mains range: 90 264 Vac -
frequency 45 ÷ 65Hz
■ Output voltage: 19 V @ 3.42 A continuous
operation
■ Mains harmonics: according to EN61000-3-2
Class-D or JEITA-MITI Class-D
■ Stand-by mains consumption: <100 mW @
230 Vac
■ Average efficiency: better than 89% without
synchronous rectification
■ EMI: according to EN55022-Class-B
■ Safety: according to EN60950
■ Dimensions: 58x121 mm, 25 mm components
maximum height
■ PCB: single side, 35 µm, CEM-1, mixed
PTH/SMT
Description
The EVL6566B-65W-QR is a demonstration
board tailored on specification of a typical hi-end
portable computer power supply. The peculiarities
of this design are the very high average efficiency
of about 90% without synchronous rectification
and very low no load consumption of 100mW at
230 Vac. The result is that this converter is
compliant to energy star eligibility criteria. The
flyback stage implements the new ST dedicated
current mode controller L6566B, operating in
quasi-resonant mode and detecting the
transformer demagnetization by pin ZCD.
The resistor on pin OSC sets the maximum
switching frequency at about 165 kHz.
Because the maximum switching frequency is
imposed, the converter operates in discontinuous
conduction mode during light load operation. The
L6566B valley skipping function is capable to
turn-on the MOSFET in valley switching even in
DCM, thus reducing switching losses.
The Power MOSFET is a standard 800 V,
STF7NM80, housed in TO-220FP package,
needing just a small heat sink. The transformer is
layer type, using a standard ferrite size EER28L,
designed according to the EN60950.
The flyback reflected voltage is ~150 V, providing
enough room for the leakage inductance voltage
spike with good margin for the reliability of the
MOSFET.
The output rectifiers are two, dual centre tap
Schottky diode in parallel, STPS20H100CFP,
housed in TO-220FP. They have been selected
according to the maximum reverse voltage,
forward voltage drop and power dissipation. The
snubber damps the oscillation produced by the
diode capacitance and the leakage inductance.
A small LC filter has been added on the output,
filtering the high frequency ripple and spikes.
Thanks to the L6566B valley skipping feature it
has been possible to dimension the power
transformer parameters optimizing efficiency at
different loads achieving an outstanding result
even without synchronous rectification.
February 2011
Doc ID 010004 Rev 1
For further information contact your local STMicroelectronics sales office.
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