AAT3175 Datasheet, PDF (1/12 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X/2X Charge Pump For White LED Flash Applications

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 S²Cwire™ (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+
C2+
C1
1µF
C1-
C2-
2.7V to 5.5V
CIN
1µF
VIN
VOUT
AAT3175
D1
D2
D3
C_OUT
1µF
GND
D1
D2
EN/SET
EN/SET
D3
D4
3175.2006.01.1.2
1