HT7466 datasheet(5/9 Pages) HOLTEK

5 / 9 page

Rev. 1.00

September 02, 2011

HT7466

Output Capacitor

TheoutputcapacitorisrequiredtomaintaintheDC

outputvoltage.CeramicorlowESRelectrolytic

capacitorsis the rule to choice of externalload

capacitorisalsocriticalandlowESRvaluecapacitors

mustbeusedtoensurestability.Thiscapacitormust

beconnectedveryclosetotheinductor,withshort

tracesforgoodnoiseperformance.

Schottky Diode

Theoutputdiodeconductswhentheinternalpower

MOSFETisswitchedoff.Therearethreeimportant

electricalparameterstoconsiderwhenchoosingthe

diode:

• Thediodemaximumreversevoltagevaluemustbe

greaterthanthemaximuminputvoltage.

• Shortrecoverytimeandlowforwardvoltage--use

aschottkydiodetype.

• Diodecurrentratingshouldbegreaterthanthe

maximumloadcurrent.

Layout Considerations

Circuitboardlayoutisaveryimportantconsideration

for switching regulators if they are to function

properly.Poorcircuitlayoutmayresultinrelated

noise problems. In order to minimise EMI and

switchingnoise,followtheguidelinesbelow:

• Alltracksshouldbeaswideaspossible.

• Theinputandoutputcapacitors,C1(C8)andC6

(C7),shouldbeplacedclosetotheVIN,VOUT

andGNDpins(C1andC8isparallel;C6andC7is

parallel).

• TheSchottkydiodeDandinductorLmustbe

placedclosetotheSWpin.

• Feedbackresistor,R1(R1-1)andR2,mustbe

placedclosetotheFBandGNDpins(R1andR1-1

isseries).

• Afullgroundplaneisalwayshelpfulforbetter

EMIperformance.

A recommended PCB layout with component

locationsisshownbelow.

Top Layer

Bottom Layer

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