LTC3442 Datasheet, PDF (17/20 Pages) Linear Integrated Systems – Micropower Synchronous Buck-Boost DC/DC Converter with Automatic Burst Mode Operation

TYPICAL APPLICATIO S
High Efficiency Li-Ion Powered Constant Current LED Driver
with Open-LED Protection
V_IN
2.5V TO
4.2V
10µF
R5
7.87k
OFF ON
3.3µH
SW1
SW2
V_IN
V_OUT
LTC3442
SD/SS
FB
R_LIM
V_C
R_T
SGND
R4
2k
57.6k
BURST
PGND
V_OUT
1nF
R2
200k
4.7µF
R3
95.3k
47pF _R1
301k
I_LED = 500mA
LHXL-PW03
OPEN LED VOLTAGE LIMIT = (R4+R5)*0.95/R4
R2 = R1/1.5
I_LED = 24 • (R1+R2+R3)/(R1 • R3) AMPS
3442 TA04a
LTC3442
LED Driver Efficiency
vs LED Current
100
V_IN = 3.6V
98 _750kHz
96
94
92
90
88
86
84
82
80
0.1
LED CURRENT (A)
1.0
3442 TA04b
3442f
17