原标题：PowerInt TFS762HG RDR249 300W电源设计方案

　　powerint 公司的TFS762HG是HiperTFS系列成员,集成了两个大功率双开关正向转换器和中功率反激(副)转换器,所提供的主功率高达414W,副转换器提供高达20W功率.器件具有可编程的火线欠压(UV)检测,过压(OV)检测以及精确的延迟热关断(OTP)等保护,满负荷效率大于90%,主要应用在 PC,打印机,LCD TV,视频游戏机,大功率适配器以及工业和电器大功率适配器.本文介绍了TFS762HG产品特性和亮点, 方框图, 主输出12V/25A,待机电源5V/2.5A的电路图以及采用TFS762HG的14.5 W待机和300 W主电源参考设计电路图,材料清单和主副电源变压器电路图.

　　The HiperTFS device family members incorporate both a high-power two-switch-forward converter and a mid-power flyback (standby) converter into a single, low-profile eSIP™ power package. The single chip solution provides the controllers for the two-switch-forward and flyback converters, high- and low-side drivers, all three of the high-voltage power MOSFETs, and eliminates the converter’s need for costly external pulse transformers. The device is ideal for high power applications that require both a main power converter (two-switch forward) up to 414 W, and standby converter (flyback) up to 20 W. HiperTFS includes Power Integrations’ standard set of comprehen- sive protection features, such as integrated soft-start, fault and over-load protection, and hysteretic thermal shutdown. HiperTFS utilizes advanced power packaging technology that simplifies the complexity of two-switch forward layout, mounting and thermal management, while providing very high power capabilities in a single compact package. The devices operate over a wide input voltage range, and can be used following a power-factor correction stage such as HiperPFS.

　　Two-switch-forward power converters are often selected for applications demanding cost-effective efficiency, fast transient response, and accurate tolerance to line voltage fluctuation. The two-switch-forward controller incorporated into HiperTFS devices improves on the classic topology by allowing operation considerably above 60% duty cycle. This improvement reduces RMS currents conduction losses, minimizes the size and cost of the bulk capacitor, and minimizes output diode voltage ratings. The advanced design also includes transformer flux reset control (saturation protection) and charge-recovery switching of the high-side MOSFET, which reduces switching losses. This combination of innovations yields an extremely efficient power supply with smaller MOSFETs, fewer passives and discrete components, and a lower-cost transformer.

　　HiperTFS’s flyback standby controller and MOSFET solution is based on the highly popular TinySwitch™ technology used in billions of power converter ICs due to its simplicity of operation, light load efficiency, and rugged, reliable, performance. This flyback converter can provide up to 20 W of output power and the built in overload power compensation reduces component design margin.

　　TFS762HG产品亮点:

　　Protected Two-Switch Forward and Flyback Combination Solution

　　• Incorporates three high-voltage power MOSFETs, main and standby controllers, and gate drivers

　　• Level shift technology eliminates need for pulse transformer

　　• Programmable line undervoltage (UV) detection prevents turn-off glitches

　　• Programmable line overvoltage (OV) detection; latching and non-latching

　　• Accurate hysteretic thermal shutdown (OTP)

　　• Accurate selectable current limit (main and standby)

　　• Output over-current protection (OCP)

　　• Fully integrated soft-start for minimum start-up stress

　　• Simple fast AC reset

　　• Reduced EMI

　　• Synchronized 66 kHz forward and 132 kHz flyback converters

　　• Frequency jitter

　　• Eliminates up to 30 discrete components for higher reliability and lower cost

　　Asymmetrical Two-Switch Forward Reduces Losses

　　• Allows >50% duty cycle operation

　　• Reduces primary side RMS currents and conduction losses

　　• Minimizes the size and cost of the bulk capacitor

　　• Allows reduced capacitance or longer hold-up time

　　• Allows lower voltage output diodes

　　• Transformer reset control

　　• Prevents transformer saturation under all conditions

　　• Extends duty cycle to satisfy AC cycle drop out ride through

　　• Duty cycle soft-start with 115% current limit boost

　　• Satisfies 2 ms ~ 20 ms start-up with large capacitance at output

　　• Output short circuit protection (SCP) with auto-restart

　　• Remote ON/OFF function

　　• Voltage mode controller with current limit

　　20 W Flyback with Selectable Power Limit

　　• TinySwitch-III based converter

　　• Selectable power limit (10 W, 12.5 W, 15 W, or 20 W)

　　• Built-in overload power compensation

　　• Flat overload power vs. input voltage

　　• Reduces component stress during overload conditions

　　• Reduces required design margin for transformer and output diode

　　• Output overvoltage (OV) protection with fast AC reset

　　• Latching, non-latching, or auto-restart

　　• Auto-restart

　　Advanced Package for High Power Applications

　　• 434 W output power capability in a highly compact package

　　• Up to 550 W peak

　　• Simple clip mounting to heat sink

　　• Can be directly connected to heat sink without insulation pad

　　• Provides thermal impedance equivalent to a TO-220

　　• Heat slug connected to ground potential for low EMI

　　• Staggered pin arrangement for simple routing of board traces and high-voltage creepage requirements

　　• Single power package for two power converters reduces assembly costs layout size

　　TFS762HG主要优势:

　　• Single chip solution for two-switch forward main and flyback standby

　　• High integration allows smaller form factor and higher power density designs

　　• Incorporates control, gate drivers, and three power MOSFETS

　　• Level shift technology eliminates need for pulse transformer

　　• Protection features include: UV, OV, OTP, OCP, and SCP

　　• Transformer reset control

　　• Prevents transformer saturation under all conditions

　　• Allows >50% duty cycle operation

　　• Reduces primary side RMS currents and conduction losses

　　• Standby supply provides built-in overload power compensation

　　• Up to 434 W total output power in a highly compact package

　　• Up to 550 W peak

　　• High efficiency solution easily enables design to meet stringent efficiency specifications

　　• >90% efficiency at full load

　　• No-load regulation and low losses at light-load

　　• Simple clip mounting to heat sink without need for insulation pad

　　• Halogen free and RoHS compliant

　　TFS762HG应用:

　　• PC

　　• Printer

　　• LCD TV

　　• Video game consoles

　　• High-power adapters

　　• Industrial and appliance high-power adapters

　　图1.TFS762HG两开关正向转换器方框图

　　图2.TFS762HG两开关正向和反激(副)转换器简化电路图

　　图3.TFS762HG高效电路图:主输出12V/25A, 副电源5V/2.5A

　　采用TFS762HG的14.5 W副和300 W主电源参考设计

　　参考设计主要特性:

　　High efficiency Main and Standby converters

　　Remote on/off

　　Built-in main and standby undervoltage thresholds protection ensures graceful

　　power supply start-up and shutdown

　　Latching output overvoltage protection

　　Integrated high-side driver

　　Output short-circuit and open loop protection

　　Main transformer reset protection

　　Flat standby overload versus input voltage

　　This document is an engineering report describing a 5 V, 2.9 A Standby and a 12 V, 25 A Main power supply utilizing the TFS762HG device from the HiperTFS family.

　　This example power supply uses a fixed DC input voltage, but in a typical application, it would be connected to a PFC boost input stage, delivering approximately 385 VDC to implement a 300 W power supply with various output voltages. A lab bench DC power supply capable of 400 VDC at 3 A or an AC input rectifier stage is required supply to the input for evaluation. It is also possible to use the power factor circuit RDK-236 to provide the regulated 385 VDC needed to power RDK-249.

　　Typically PC power supplies have a universal AC input power factor corrected (PFC) input stage but as the bias standby supply must operate before the PFC stage is active,the Standby output must operate with the DC equivalent of universal AC input voltages(85 VAC to 265 VAC and 100 VDC to 400 VDC).

　　图4.采用TFS762HG的电源外形图

　　采用TFS762HG的电源指标:

　　图5.采用TFS762HG的参考设计电源电路图

　　采用TFS762HG的参考设计电源材料清单(BOM):

　　Standby Transformer Specification

　　图6. 副电源变压电路图

　　Main Transformer Specification

　　图7.主电源变压电路图