
The AS3642 can be directly connected to an (existing) I C bus (e.g. from the baseband or camera processor). All func-
of the flash is programmed by the I C interface, but the exact starting time is defined by this input- see External Strobe
AS3642
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
2
tions are accessible by this interface. An strobe input can be done by adding a diode (with an optional resistor in
series) to the LED_OUT pin. Setting the register bit external_strobe =1 enable this input as a strobe input. The duration
2
Input on page 10 .
External Components
Input Capacitor C VIN
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Ceramic
capacitors are required for input decoupling and should be located as close to the device as is practical.
Table 10. Recommended Input Capacitor
Part Number
CL05A395MQ5NQKL
C
4.7μF +/-10%
>1.6μF @ V VIN
TC Code
X5R
ESR
<20m ?
Rated
Voltage
6V3
Size
0402
Manufacturer
Samsung Electro-
Mechancs
www.sem.samsung.co.kr
If a different input capacitor is chosen, ensure similar ESR value and at least 1.6 μ F capacitance at the maximum input
supply voltage. Larger capacitor values (C) may be used without limitations.
Output Capacitor C VOUT
Low ESR capacitors should be used to minimize VOUT ripple. Multi-layer ceramic capacitors are recommended since
they have extremely low ESR and are available in small footprints. The capacitor should be located as close to the
device as is practical.
X5R dielectric material is recommended due to their ability to maintain capacitance over wide voltage and temperature
range.
Table 11. Recommended Output Capacitor
Part Number
ECJUNBPJ155K
C
2x1.5μF +/-15%
TC Code
X5R
ESR
<10m ?
Rated
Voltage
6V3
Size
0405
2-array
Manufacturer
Panasonic
www.panasonic.com
CL14A185MQ8SAKL
Samsung Electro-
Mechancs
www.sem.samsung.co.kr
inductor should have low DC resistance (DCR) to reduce the I R power losses - high DCR values will reduce effi-
If a different output capacitor is chosen, ensure similar ESR values and at least 1.0μF capacitance at maximum output
voltage.
Inductor L DCDC
The fast switching frequency (4MHz) of the AS3642 allows for the use of small SMDs for the external inductor. The
2
ciency.
Table 12. Recommended Inductor
Part Number
LQM21PN1R0NGC
ELGTEA1R0SN
L
1.1μH
1.0μH
DCR
100m ?
L @ 0.9A
>0.7μH
>0.7μH
Size
2x1.25x0.9mm
2x1.25x0.9mm
Manufacturer
Murata
www.murata.com
Panasonic
www.panasonic.com
www.austriamicrosystems.com/AS3642
1.2-2
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