Datasheet

LTC3442
16
3442fb
For more information www.linear.com/LTC3442
TYPICAL APPLICATIONS
Multi-Input 3.3V at 600mA Boost Converter for Portable Applications
with Automatic Burst Mode Operation and Average Input Current Limit for USB Powered Devices
SW1
V
IN
SHDN/SS
R
LIM
R
T
SGND
SW2
V
OUT
FB
V
C
BURST
PGND
LTC3442
0.01µF
C
IN
: TAIYO YUDEN JMK212BJ106MG
C
OUT
: TAIYO YUDEN JMK325BJ476MM
L1: TDK RLF7030T-4R7M3R4
2.5V TO 5.5V
Li-Ion
15k
340k
200k
2.2k
0.01µF
220pF
V
OUT
3.3V
600mA
200k
470pF
3442 TA03
64.9k143k
1M
1nF
R
SNUB
**
1Ω
USB/5V
2Ω
D1
MBRM120T3
1nF
A SNUBBER RESISTOR IS REQUIRED TO PREVENT
RINGING IF THERE IS SIGNIFICANT INPUT INDUCTANCE,
SUCH AS FROM A USB CABLE
**
USB
PRESENT
2N7002
143k
C
IN
10µF
L1
4.7µH
C
OUT
22µF
High Efficiency Li-Ion Powered Constant Current LED Driver
with Open-LED Protection LED Driver Efficiency vs LED Current
SW1
V
IN
SHDN/SS
R
LIM
R
T
SGND
SW2
V
OUT
FB
V
C
BURST
PGND
LTC3442
V
IN
2.5V TO
4.2V
LHXL-PW03
4.7µF
V
OUT
1nF
3442 TA04a
3.3µH
47pF
10µF
R5
7.87k
*OFF ON
OPEN LED VOLTAGE LIMIT = (R4 + R5) • 0.95/R4
* NOTE: THE SHDN/SS VOLTAGE MUST BE NO MORE THAN 0.5V BELOW V
IN
WHEN ENABLED.
R2 = R1/1.5
I
LED
= 24 • (R1 + R2 + R3)/(R1 • R3) AMPS
R3
95.3k
R2
200k
R1
301k
57.6k
R4
2k
I
LED
= 500mA
LED CURRENT (A)
0.1
EFFICIENCY (%)
1.0
3442 TA04b
80
84
88
92
96
82
86
90
94
98
100
V
IN
= 3.6V
750kHz