LTC3202
Low Noise, High Efficiency
Charge Pump for White LEDs
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Low Noise Constant Frequency Operation
25% Less Input Current Than Doubler Charge Pump
High Output Current: Up To 125mA
Small Application Circuit
Regulated Output Voltage or Current
Automatic Soft-Start
V
IN
Range: 2.7V to 4.5V
No Inductors
1.5MHz Switching Frequency
I
CC
< 1µA in Shutdown
Available in 10-Pin MSOP and 3mm
×
3mm
DFN Packages
The LTC
®
3202 is a low noise, constant frequency charge
pump DC/DC converter that uses fractional conversion to
increase efficiency in white LED applications. The part can
be used to produce a regulated voltage or current of up to
125mA from a 2.7V to 4.5V input. Low external parts count
(two flying capacitors and two small bypass capacitors at
V
IN
and V
OUT
) make the LTC3202 ideally suited for small,
battery-powered applications.
An internal 2-bit DAC allows LED current to be adjusted for
LED brightness control. The LTC3202 also has thermal
shutdown protection and can survive a continuous short-
circuit from V
OUT
to GND. Built-in soft-start circuitry
prevents excessive inrush current during start-up. High
switching frequency enables the use of small external
capacitors. A low current shutdown feature disconnects
the load from V
IN
and reduces quiescent current to less
than1µA.
The LTC3202 is available in the 10-pin MSOP and 3mm
×
3mm DFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
White LED Backlighting
Programmable Boost Current Source
TYPICAL APPLICATIO
C2
1µF
C3
1µF
Programmable White LED Power Supply
Input and Output Ripple
V
IN
(AC COUPLED)
20mV/DIV
8
C1
+
10
CURRENT
PROGRAMMING
V
IN
3V TO 4.5V
C1
1µF
1
4
D0
D1
V
IN
7
C1
–
9
C2
+
6
C2
–
V
OUT
0mA TO 125mA
TOTAL CURRENT
3
LTC3202
FB
GND
5, 11
2
C4
1µF
36Ω
36Ω
36Ω
36Ω
36Ω
36Ω
V
OUT
(AC COUPLED)
20mV/DIV
500ns/DIV
V
IN
= 3.6V
C
IN
= C
OUT
= 1µF
I
OUT
= 60mA
3202 G09
C1, C2, C3, C4 = MURATA GRM 39X5R105K6.3 OR TAIYO YUDEN JMK107BJ105MA
3202 TA01
U
3202fa
U
U
1
LINER [ LINEAR TECHNOLOGY ]
