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19 V - 65 W quasi resonant flyback adapter board
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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.

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Data Brief

Key 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


图案 资源


Technical Documentation

Product Specifications

描述 版本 大小
DB1229: 19 V - 65 W quasi resonant flyback adapter board
1.1 123 KB

Hardware Resources

Board Manufacturing Specification

描述 版本 大小
EVL6566B-65W-QR gerber files
1.0.0 236 KB

Bill of Materials

描述 版本 大小
BOM for EVL6566B-65W-QR board
1.0.0 23 KB

Schematic Pack

描述 版本 大小
Board schematics for EVL6566B-65W-QR board
1.0.0 72 KB

样品 & 购买

产品型号 Marketing StatusCore ProductOrder From STUnit Price (US$)*
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
EVL6566B-65W-QRActiveL6566BH-Distributor reported inventory date: 2014-04-18
Distributor NameRegionStockMin. order

(*) 建议零售价格仅用于预算,以美元为单位,每。的报价,以当地货币计算的价格,请联系您当地的 ST 销售办事处 或我们的 分销商
(**) 材料声明表格上提供st.com可以是一般的文件,根据最常用的包,包内的家庭。出于这个原因,他们可能不是100%准确,对于一个特定的设备。请联系我们 销售支持 在特定设备上的信息。
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