Analog Integrated Circuit Device Data



Freescale Semiconductor

29

34844

TYPICAL APPLICATIONS

COMPONENTS CALCULATION

Slope Compensation

Slope Compensation can be expressed either in terms of Ampers/Second or as Volts/Second, through the use of the transfer

resistance.

The following formula express the Slope Compensation in terms of V/s:

To have this slope compensation, the following resistor should be set.

Variable Definition

D = Boost duty cycle

VOUT = Output voltage

VD = Diode forward voltage

VIN = Input voltage

VSW = VDROP of internal switch

VOUT = Output voltage ripple ratio

IINAVG = Average input current

IOUT = Output current

r = Input current ratio

IINMAX = Maximum input current

IRMSCIN = RMS current for input capacitor

IRMSCOUT = RMS current for output capacitor

L = Inductor

RW = Inductor winding DC resistance

fSW = Boost switching frequency

CSG = Current sense gain = 0.2 V/A

ACSA = Current sense amplifier gain = 9

RSENSE = Current sense resistor = 22 m

COUT = Output capacitor

RCOMP = Compensation resistor

GM = OTA transconductance

ESRCOUT = ESR of output capacitor

fRHPZ = Right half plane zero frequency

fCROSS = Crossover frequency

CCOMP1 = Compensation capacitor

CCOMP2 = Shunt compensation capacitor

VSLOPE = Slope compensation (V/s)

RSLOPE = External resistor for slope compensation

VSLOPE

Vout Vin

–

 CSG



L2



-----------------------------------------------------

=

Where “L” is in

H

RSLOPE

33

3

10

VSLOPE 5



----------------------------------

=