34845B datasheet(17/21 Pages) FREESCALE

Part #	34845B

Description	Low Cost 6 Channel LED Backlight Driver with Integrated Power Supply

PDF	21 Pages

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Manufacturer	FREESCALE [Freescale Semiconductor, Inc]

Direct Link	http://www.freescale.com

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17 / 21 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

34845

TYPICAL APPLICATIONS

COMPONENTS CALCULATION

Variable definition

D = Duty cycle

VOUT = Output voltage

VD = Diode voltage

VIN = Input voltage

VSW = Internal switch voltage drop.

ΔVOUT = Output voltage ripple

IIN-AVG = Average input current = IL-AVG

IOUT = Output current

IIN-MAX = Maximum input current

r = Current ripple ratio at the inductor =

ΔIL/ IL-AVG

IRMS-CIN= RMS current for the input capacitor

IRMS-COUT= RMS current for output capacitor

L = Inductor.

RINDUCTOR= Inductor winding resistor

FSW= Boost switching frequency

COUT = Output capacitor

RCOMP = Compensation resistor

GM= OTA transconductance

ESRCOUT= ESR of the output capacitor

fRHPZ= Right half plane zero frequency

fCROSS= Crossover frequency

CCOMP1= Compensation capacitor

CCOMP2= Shunt compensation capacitor

34845B Datasheet(PDF) 17 Page - Freescale Semiconductor, Inc