AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
VIN
C1+
C1
1µF
D1
RB1
D2
RB2
D3
RB3
D4
RB4
C1-
C2+
VOUT
CIN
COUT
C2
VBATTERY
AAT3124
1µF
1µF
1µF
C2-
Resistor R is optional
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
D5
D6
GND
RB5
RB6
Resistor R is optional
AAT3124 Driving Two Groups of Paralleled White LEDs (e.g., main and sub-LCD backlights).
VIN
C1+
C1
1µF
C1-
VOUT
C2+
CIN
COUT
C2
1µF
VBATTERY
AAT3124
1µF
1µF
C2-
D1
D2
D3
D4
D5
D6
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
GND
RB1
*
RB2
*
RB3
*
RB4
*
RB5
*
RB6*
Photo-Flash LED
Resistor R is optional
*In some applications, white LED forward voltages (VF) can vary significantly. Ballast resistors between the LED cathodes and ground are recommended
for balancing the forward voltage differences. The ballast resistor value may be approximated by the following equation:
VSOURCE - VF
=
RB
IF
AAT3124 Driving a High-Current Photo-Flash LED.
14
3123.2005.12.1.4
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
