LTC3202 Datasheet, PDF (1/12 Pages) Linear Technology – Low Noise, High Efficiency Charge Pump for White LEDs

LTC3202
Low Noise, High Efficiency
Charge Pump for White LEDs
FEATURES
s _{Low Noise Constant Frequency Operation}
s _{25% Less Input Current Than Doubler Charge Pump}
s _{High Output Current: Up To 125mA}
s _{Small Application Circuit}
s _{Regulated Output Voltage or Current}
s _{Automatic Soft-Start}
s _{VIN Range: 2.7V to 4.5V}
s _{No Inductors}
s _{1.5MHz Switching Frequency}
s _{ICC < 1µA in Shutdown}
s _{Available in 10-Pin MSOP and 3mm × 3mm}
DFN Packages _U
APPLICATIO S
s _{White LED Backlighting}
s _{Programmable Boost Current Source}
DESCRIPTIO
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.
TYPICAL APPLICATIO
Programmable White LED Power Supply
C2
C3
1µF
1µF
8 79 6
C1⁺
10 _D0
CURRENT
C1^–
C2⁺
C2^–
0mA TO 125mA
3 ^{TOTAL CURRENT}
V_OUT
PROGRAMMING 1 _{D1 LTC3202}
V_IN
3V TO 4.5V
C1
1µF
4 _VIN
2
FB
GND
5, 11
C4
1µF
36Ω
36Ω
36Ω
36Ω
36Ω 36Ω
C1, C2, C3, C4 = MURATA GRM 39X5R105K6.3 OR TAIYO YUDEN JMK107BJ105MA
3202 TA01
Input and Output Ripple
V_IN
(AC COUPLED)
20mV/DIV
V_OUT
(AC COUPLED)
20mV/DIV
V_IN = 3.6V
500ns/DIV
C_IN = C_OUT = 1µF
I_OUT = 60mA
3202 G09
3202fa
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