Datasheet

LT3755/LT3755-1/LT3755-2
22
37551fd
Typical applicaTions
21W Buck-Boost Mode with 250:1 PWM Dimming and Open LED Protection
V
IN
LT3755-2
GND
SHDN/UVLO
V
REF
INTV
CC
499k
100k
0.1Ω
21.5V
1A
50V
2.2µF
2s
V
IN
8V TO
36V
L1
15µH
M1: VISHAY SILICONIX SI7850DP
M2: VISHAY SILICONIX SI2319DS
Q1: ZETEX FMMT558
Q2: MMBTA42
D1: DIODES INC. PDS560
L1: SUMIDA CDRH127/LD-150
93.1k
392k
1.5k
20.0k
100k
549k
75.0k
0.01µF
4.7µF
CTRL
1k
V
C
4.7k
4700pF
37551 TA07a
OPENLED
SS
FB
ISN
ISP
PWMOUT
PWM PWM
SENSE
RT
GATE
100V
2.2µF
2s
Q2
M2
D1
Q1
28.7k
375kHz
0.02Ω
M1
V
IN
Buck-Boost Mode LED Current vs Low Input VoltageBuck-Boost Mode Efficiency vs Input Voltage
37551 TA07b
EFFICIENCY (%)
INPUT VOLTAGE (V)
0 1510 25 305 20 35 40
80
90
100
85
95
37551 TA07c
LED CURRENT (A)
INPUT VOLTAGE (V)
8 1110 13 149 12 15 16
0.8
1
0.95
1.10
0.85
0.9
1.05