11

LR8

1235 Bordeaux Drive, Sunnyvale, CA 94089

TEL: (408) 744-0100 • FAX: (408) 222-4895

www.supertex.com

11/30/01rev.1

Ct

II

V

OUT

BOOT

PWM

LIM

HYS

>

−

The minimum capacitance required for given boot-up time is

given by the following equation:

Remember that this equation is valid only when PWM current

exceeds the LR8’s current limit.

where

C

OUT

= Capacitor at LR8 output

t

I

PWM

= Current used by PWM controller

I

LIM

= LR8 current limit (10mA min)

V

HYS

= PWM controller UVL hysteresis