AAT3132 Datasheet, PDF (7/14 Pages) Advanced Analogic Technologies – High Efficiency 1.5X Fractional Charge Pump for White LED Applications

AAT3132/32A
High Efficiency 1.5X Fractional Charge
Pump for White LED Applications
Functional Block Diagram
VIN
Soft-Start
Control
1MHz
Oscillator
Voltage
Reference
1.5X
Charge
Pump
C1+
C1-
C2+
C2-
OUT
EN/SET
S²Cwire
Interface
Current
Reference
32x16 bit
ROM
32x16 bit
ROM
D1
Quad
D2
Output
DAC
D3
Single
D4
Output
DAC
GND
Functional Description
The AAT3132/32A is a high efficiency (1.5X) frac-
tional charge pump device intended for white LED
backlight applications. It consists of a 1.5X charge
pump with multiple current source outputs. To max-
imize power conversion efficiency, an internal feed-
back control sensing circuit monitors the voltage
required on the constant current source outputs.
The AAT3132/32A requires only four external
components: two 1µF ceramic capacitors for the
charge pump flying capacitors (C₁ and C₂), one
1µF ceramic input capacitor (C_IN), and one
0.33µF to 1µF ceramic output capacitor (C_OUT).
The 1.5X charge pump output is converted into
three (D1 to D3) constant current outputs to drive
three individual LEDs with a maximum current of
20mA each, and one (D4) constant current output
with a maximum current of 25 or 30mA. The cur-
3132.2005.12.1.4
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