AAT3122_05 ANALOGICTECH [Advanced Analogic Technologies], AAT3122_05 Datasheet - Page 11

• Manufacturer Part Number: AAT3122_05
• Description: High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

Additional Application Circuit
*In some applications, white LED forward voltages (V
recommended for balancing the forward voltage differences. The ballast resistor value may be approxiamted by the following equation:
V
datasheet for maximum V
I
V
R
3122.2005.11.1.3
F(MAX)
F(MAX)
IN(MIN)
B
= Ballast resistor value in ohms.
= Maximum forward current used to drive an individual LED.
= Maximum expected LED forward voltage at the given maximum forward current level. Refer to the LED manufacturers’
= Minimum input supply voltage for the application.
V
BATTERY
F
specifications.
C
1µF
IN
EN/SET
C
1µF
OUT
VIN
VOUT
EN/SET
R
AAT3122
B
F
=
) can vary significantly. Ballast resistors between the LED cathodes and ground are
GND
(V
IN(MIN)
High Efficiency 1X/1.5X Fractional Charge
C1+
C1-
C2+
C2-
D1
)1.5 - (V
I
F(MAX)
F(MAX)
C1
1µF
C2
1µF
Pump for White LED Applications
+ 250mV)
R
D1
B
*
R
D2
B
*
R
D3
B
*
R
D4
B
*
R
AAT3122
D5
B
*
R
D6
B
*
11