Preliminary Datasheet
BOOST CONTROLLER
AP3039
Application Information (Continued)
Soft Start
AP3039 has a soft start circuit to limit the inrush
current during startup. The time of soft start is
controlled by an internal 12μA current source and an
external soft start capacitor C connected from SS pin
SS
to GND (see Figure 21). The effective C voltage for
SS
Soft Start is from 0 to 2.3V, the time of Soft Start is:
t
= C *2.3V/12μA
SS
SS
Typical Application
VIN : 6V to 27V
VOUT
L
D1
CIN
R1
R2
COUT
VIN
R3
R4
UVLO
Q1
OUT
CS
VCC
R5
CV
RCS
EN
OFF ON
OV
FB
RT
RT
SS
OFF ON
CSS
RC
R6
SHDN
COMP
GND
CC
U1 AP3039
Figure 21. AP3039 Application Circuit
May 2008 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
13
BCDSEMI [ BCD SEMICONDUCTOR MANUFACTURING LIMITED ]
