18

NXP Semiconductors

34845

6.2.5

Variable definition

D = Duty cycle

VOUT = Output voltage

VD = Diode voltage

VIN = Input voltage

VSW = Internal switch voltage drop.

∆VOUT = 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

6.2.6

Component suggestions

The Component Suggestions only apply to the conditions shown. Therefore, adjustments are necessary for different application

conditions.

Table 5. Component Suggestion Table

Application

Case

VIN(min)

VIN(Max)

VO(max)

VOVP

fBOOST

ILED per

channel

ROVP_UPPER

ROVP_LOWER

1

9.0 V

12 V

30 V

35 V

600 kHz

20 mA

680 k

Ω

167 k

Ω

2

6.0 V

12 V

43 V

48 V

300 kHz

23 mA

680 k

Ω

114 k

Ω

Application

Case

L(min)

L(min)

Continuous

mode

CIN(min)

COUT(min)

RCOMP at

VPWM =3.3V

RSHUNT at

VPWM =3.3 V

CCOMP1

CCOMP2

1

22

μH

33

μH

1x10

μF; X7R;

25 V

2 x 4.7

μF;

X7R; 50 V

3.3 k

Ω

10 k

Ω

33 nF

220 pF

2

22

μH

33

μH

1x10

μF; X7R;

25 V

4 x 2.2

μF;

X7R; 100 V

2.0 k

Ω

16 k

Ω

56 nF

220 pF

ISAT min = 2.6 A