AAT3175
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Flash Applications
General Description
The AAT3175 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-mode
load switch (1X), fractional (1.5X), and doubling
(2X) conversion to maximize efficiency for white
LED flash applications. The AAT3175 is capable of
driving up to three flash LEDs at 300mA total cur-
rent from a 2.7V to 5.5V input. A low external parts
count (two 1µF flying capacitors and two small 1µF
capacitors at V
IN
and V
OUT
) make this part ideally
suited for small battery-powered applications.
AnalogicTech's S
2
Cwire™ (Simple Serial Control™)
serial digital input is used to enable, disable, and
set current for all LEDs with 16 level settings down
to 0.
The AAT3175 is equipped with built-in protection
for V
OUT
short-circuit condition and auto-disable for
load short-circuit condition on any one of the chan-
nels. Built-in soft-start circuitry prevents excessive
inrush current during start-up. A low-current shut-
down feature disconnects the load from V
IN
and
reduces quiescent current to less than 1µA.
The AAT3175 is available in a Pb-free, space-saving,
thermally-enhanced 12-pin 3x3mm TDFN package.
Features
•
•
•
•
•
•
•
•
•
•
•
•
ChargePump
™
V
IN
Range: 2.7V to 5.5V
Up to 300mA Total Flash Current
Fully Programmable Current with Single Wire
— 16 Logarithmic Current Levels
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives 3-in-1 or 2-in-1 Flash LEDs
— 0.5% Current Matching
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Automatic Soft-Start
I
Q
<1µA in Shutdown
TDFN33-12 Package
Applications
•
•
•
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Mobile Phones
Typical Application
C1+
C1
1µF
C2+
C1-
2.7V to 5.5V
C
IN
1µF
C2-
VOUT
VIN
AAT3175
GND
D1
D2
D1
D2
D3
C
OUT
1µF
EN/SET
EN/SET
D3
D4
3175.2006.01.1.2
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
