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AAT3119 Datasheet, PDF (14/16 Pages) Advanced Analogic Technologies – High Efficiency 2X Charge Pump | |||
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AAT3119
High Efficiency 2X Charge Pump
CFLY
1µF
V
IN
IN
CIN
1µF
OUT
4.5V
COUT
1µF
AAT3119
RF
Enable
EN
GND
Flash LED
Figure 2: Flash LED Application.
If a "light" or "movie" mode is also needed along
with the flash function, this can be accomplished
with the addition of a second ballast resistor with a
flash function gating MOSFET switch as shown in
Figure 3. Refer to the following equations for the
calculation of flash and light resistors, RF and RL.
RL
=
(VOUT -
IF
VF)
Where:
RL =
VOUT =
VF =
IF
=
Light mode ballast resistor value in
ohms (â¦)
Regulated charge pump output voltage
(typically 4.5V)
Flash LED forward voltage at the
desired forward current
Desired flash LED forward current in
the "light" mode
RF
=
(VOUT - VF)
IF
- RDS
Where:
RF =
RDS =
VOUT =
VF =
IF
=
Flash ballast resistor value in ohms (â¦)
Flash gating MOSFET on resistance
Regulated charge pump output voltage
(typically 4.5V)
Flash LED forward voltage at the
desired forward current
Desired flash LED forward current
14
3119.2005.08.1.1
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