Typical Applications - Linear Technology LT3956 Series Manual

LT3956

Typical applicaTions

V
IN
6V TO 60V
(80V TRANSIENT)
C
VIN
2.2µF

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