Linear Technology LT3956 Series, Manual, Page: 16 / 20

LT3956
3956f
94% Efficient 25W White LED Headlamp Driver
Typical applicaTions
PWM Waveforms for 25W Headlamp Driver
V
IN
SW
LT3956
L1
22µH
D1
GND V
C
INTV
CC
EN/UVLO
PGND
V
REF
ISP
332k
100k
INTV
CC
R1
332k
C
VIN
2.2µF
s
2
C
OUT
2.2µF
s
5
C
C
4.7nF
V
IN
6V TO 60V
(80V TRANSIENT)
C
SS
47nF
R2
100k
R
C
20k
R
T
28.7k
375kHz
C
VCC
4.7µF
40.2k
CTRL
R4
16.2k
R3
1M
R
S
0.68Ω
370mA
M1
INTV
CC
3956 TA02a
VMODE
PWM
SS
RT
ISN
FB
PWMOUT
M1: VISHAY SILICONIX Si2328DS
D1: DIODES INC PDS5100
L1: COILTRONICS DR125-220
C1, C2: MURATA GRM42-2x7R225
SEE SUGGESTED LAYOUT (FIGURE 5)
25W LED STRING
(CURRENT DERATED
FOR V
IN
< 11V)
5µs/DIV
PWM
I
LED
200mA/DIV
I
LI
1A/DIV
3956 TA02b
V
OUT
= 68V
V
IN
= 15V