AAT3153
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Functional Block Diagram
C1+ C1- C2+ C2-
1X, 1.5X, and 2X
VOUT
VIN
Charge Pump
Soft-Start
Control
1MHz
Oscillator
Voltage
Reference
D/A
D1
6 x 16 bit
ROM
D/A
D2
D3
D4
D5
D6
D6
D/A
D/A
D/A
D/A
S2Cwire
Interface
EN/SET
6 x 16 bit
ROM
charge pump is enabled when any of the four cur-
rent sink inputs near dropout. The charge pump ini-
tially starts in 1.5X mode. If the charge pump out-
put drops enough for any current source output to
become close to dropout, the charge pump will
automatically transition to 2X mode. The AAT3153
requires only four external components: two 1µF
ceramic capacitors for the charge pump flying
capacitors (C1 and C2), one 1µF ceramic input
capacitor (CIN), and one 0.33µF to 1µF ceramic
charge pump output capacitor (COUT).
Functional Description
The AAT3153 is a tri-mode load switch (1X) and
high efficiency (1.5X or 2X) charge pump device
intended for white LED backlight applications. To
maximize power conversion efficiency, an internal
sensing circuit monitors the voltage required on
each constant current sink input and sets the load
switch and charge pump modes based on the input
battery voltage and the current sink input voltage.
As the battery discharges over time, the AAT3153
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3153.2005.12.0.93
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
