Datasheet

LT3478/LT3478-1
21
34781f
TYPICAL APPLICATIO S
U
LT3478-1
SHDN
V
REF
OUT
LED
CTRL2
CTRL1
OVPSET
PWM SS V
C
R
T
V
IN
V
S
LSW
C2
4.7µF
16V
R1
100k
R4
510Ω
R5
510Ω
R
T
69.8k
f
OSC
= 500kHz
1kHz
R2
34k
PWM
DIMMING RATIO = 200:1
L1: CDRH105R-6R8
D1: B320
Q1: Si2302ADS
Q2: Si2315BDS
LED: LUXEON III (WHITE)
1A
Q1
Q2
D1
3478 TA06a
L1
6.8µH
3.3V
0V
V
IN
3.8V TO 6.5V
NiMH 4×
C1
10µF
10V
C
C
0.1µF
C
SS
1µF
R3
10k
OFFON
35764
V
IN
(V)
EFFICIENCY (%)
80
75
70
50
55
60
65
3478 TA06b
SINGLE LED
LUXEON III (WHITE)
I
LED
= 1A
f
OSC
= 500kHz
PWM DUTY CYCLE = 100%
4W, 1 LED at 1A, Buck-Boost Mode LED Driver
Effi ciency vs V
IN