Rev. 1.10

6

July 17, 2013

HT7A6005

GD

VCC

MF

CS

COMP/FB

GND

RT

VREF

2.2kW

0.1mF

470mF/50V

10W

1N4148

20W

0.22W

10kW

IRF540

0.22W

1nF

470kW

33pF

HFB20HJ20C

0.1mF/100V

46mH

2kW

40kW

470mF

/63V

820W

220pF

Vo=55V/75W

Figure 8. Constant Voltage Boost Application (DC-DC Boost)

Multi-Function Pin

AspeciallydesignedMixed-Signal/AnalogInterface

isprovidedintheHT7A6005.Byconnectingthe

Multi-Function(MF)pintodifferentsystemsensing

points,theHT7A6005canbeusedfordifferentcircuit

topologiessuchasIsolationFlybackorNon-Isolation

DC-DCBuck/Boost.TheMFpincanalsobeusedas

anLEDdimmingpinforBuckLEDdriving.Some

applicationcircuitexamplesareintroducedinthe

followingpages.

Constant Voltage Boost Application

AConstantVoltage(CV)Boostapplicationcircuitis

showninFigure8.ThiscircuitcanbeusedwithDC

inputsof16~24VandprovidesaDCoutputof55V±

5%with75Woutputpower.Theoutputpowerlevel

canbechangedbychoosingasuitableinductorvalue

andpowerMOSFET,whiletheoutputvoltagecan

bechangedbychoosingasuitablefeedbackresistor

ratio.

Boost Constant Current (CC) LED Driver

for Back-light

A Boost CC LED Driver shown in Figure 9 is

designed for LED backlight applications. The

topology is similar to Boost topologies, but the

feedbackpointischangedfromtheVoltageOutput

terminaltotheCurrentSenseResistor.Thiscircuit

canbeusedwithaDCinputof16~24Vandprovides

aDCoutputof55Vwith75Woutputpower.This

circuit’sconstantcurrentcapabilityismorethanthat

requiredbybacklightsandalsogoodenoughforLED

lightingapplications.

Buck Constant Current LED Lighting

Driver

AlowcostBuckConstantCurrentLEDLighting

driverisintroducedinFigure10.Unliketheusual

LEDdriveswhichhaveafixed-voltagerangeand

constantcurrentcontrol,thiscircuitcansupportvery

highoutputvoltages,perhapsforhighLEDcount

serialconfigurations, withnomaximumvoltage

limitations.HeretheMFpincanbeusedasaPWM

dimmingpin.

Constant Voltage Buck Application

AConstantVoltage(CV)Buck(High-SideBuck)

applicationcircuitisshowninFigure11.Thiscircuit

canbeusedwithDCinputsof24Vorhighervoltage

andprovidesaConstantDCvoltageoutput.The

outputpowerlevelcanbechangedbychoosinga

suitableinductorvalue,Transformer’sturnratioand

powerMOSFET,whiletheoutputvoltagecanbe

changedbychoosingasuitablefeedbackresistor

ratio.

Primary Side Feedback, Isolation Flyback

AC-DC Converter

ThedevicecanalsocanbeusedforisolationAC-

DCapplications.Atypicalprimarysidefeedback,

isolation FlybackAC-DC converter is shown in

Figure12.