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 turn-on the MOSFET in valley switching even in DCM, thus reducing switching losses. Safety: according to EN60950 Dimensions: 58x121 mm, 25 mm components The Power MOSFET is a standard 800 V, maximum height STF7NM80, housed in TO-220FP package, needing just a small heat sink. The transformer is PCB: single side, 35 m, CEM-1, mixed layer type, using a standard ferrite size EER28L, PTH/SMT designed according to the EN60950. The flyback reflected voltage is ~150 V, providing Description enough room for the leakage inductance voltage The EVL6566B-65W-QR is a demonstration spike with good margin for the reliability of the board tailored on specification of a typical hi-end MOSFET. portable computer power supply. The peculiarities The output rectifiers are two, dual centre tap of this design are the very high average efficiency Schottky diode in parallel, STPS20H100CFP, of about 90% without synchronous rectification housed in TO-220FP. They have been selected and very low no load consumption of 100mW at according to the maximum reverse voltage, 230 Vac. The result is that this converter is forward voltage drop and power dissipation. The compliant to energy star eligibility criteria. The snubber damps the oscillation produced by the flyback stage implements the new ST dedicated diode capacitance and the leakage inductance. current mode controller L6566B, operating in quasi-resonant mode and detecting the A small LC filter has been added on the output, transformer demagnetization by pin ZCD. filtering the high frequency ripple and spikes. The resistor on pin OSC sets the maximum Thanks to the L6566B valley skipping feature it switching frequency at about 165 kHz. has been possible to dimension the power transformer parameters optimizing efficiency at Because the maximum switching frequency is different loads achieving an outstanding result imposed, the converter operates in discontinuous even without synchronous rectification. conduction mode during light load operation. The L6566B valley skipping function is capable to February 2011 Doc ID 010004 Rev 1 1/5 For further information contact your local STMicroelectronics sales office. www.st.com 5Electrical diagram and efficiency EVL6566B-65W-QR 1 Electrical diagram and efficiency Figure 1. Electrical diagram * * -+ 3 -+ 3 2 2 2 2 6 U 6 U 6 6 . 2 2 2 2 6 /54 , , /54 5 5 + + 2 2 43- )3443- )34 6 2%& 6 2 2 + + 1 1 2 2 + + 2 2 1 1 + + :6 :6 2 2 + + 2 2 + + U 6 U 6 2 2 + + U 6 U 6 2 2 2 2 2 2 + + 2 2 + + 2 2 + + 2 2 2 2 (3 (3 (% (% 2 2 + + 44 3).+ 3).+ 2 2 + + 3403 ( &03403 ( &0 3403 ( &03403 ( &0 2 2 + + 2 2 + + 4 4 5 5 3&( 3&( +% +% 2 2 + + 2 2 + + 3 -3 - 2 2 2 2 P& K6 P& K6 (3 (3 (% 3).+44 3).+(% P& P& 1 1 34& .- 34& .- 2 2 2 2 2 2 + + 344( 344( 2 2 + + 2 2 + + P& P& U 6 U 6 2 2 2 2 ,, ,, ,, ,, 2 2 2 2 U& 6 U& 6 2 2 + + 2 2 + + + + 2 2 2 2 + + 5 *5 * 33 6&& : /3 62%& /-0 /+ 3 -3 - 1 1 -/ % 3 2 2 + + 5 5 , , 2 2 - - 2 2 - - 2 2 + + (6 6 &-/ 3 )3 2 2 - - 3 -3 - 2 2 .-.- , , (& 9 2 4 (& 9 2 4 2 2 + + P& P& & & 4% 4% U 6 U 6 2 2 .4 2 3 .4 2 3 * * -+ 3 -+ 3 6AC - 6 2/5 Doc ID 010004 Rev 1