AAT3152_05 ANALOGICTECH [Advanced Analogic Technologies], AAT3152_05 Datasheet - Page 8

• Manufacturer Part Number: AAT3152_05
• Description: High Efficiency 1X/1.5X/2X Charge Pump For White LED Applications
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

Functional Block Diagram
Functional Description
The AAT3152 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 AAT3152
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
8
EN/SET
VIN
Interface
S
2
Cwire
Reference
Oscillator
Soft-Start
Control
Voltage
1MHz
High Efficiency 1X/1.5X/2X Charge Pump
C1+
6 x 16 bit
6 x 16 bit
ROM
ROM
1X, 1.5X and 2X
Charge Pump
automatically transition to 2X mode. The AAT3152
requires only four external components: two 1µF
ceramic capacitors for the charge pump flying
capacitors (C
capacitor (C
charge pump output capacitor (C
The four constant current sink inputs (D1 to D4)
can drive four individual LEDs with a maximum cur-
rent of 20mA each. The unused sink inputs must be
connected to V
only in 2X charge pump mode. The S
interface enables the AAT3152 and sets the cur-
rent sink magnitudes. S
independent control of two groups of current sink
input: D1-D3 and D4.
C1- C2+
C2-
For White LED Applications
D/A
D/A
D/A
D/A
IN
1
), and one 0.33µF to 1µF ceramic
OUT
and C
, otherwise the part will operate
VOUT
D1
D2
D3
D4
GND
2
), one 1µF ceramic input
2
Cwire addressing allows
OUT
AAT3152
).
3152.2005.08.1.2
2
Cwire serial