www.austriamicrosystems.com/AS3635

1.4-8

16 - 20

AS3635

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

The photoflash capacitor stores the energy for the flash. Its capacitance define the maximum available energy. Using

higher value capacitors as shown in Table 6 is possible, but will increase the charging time.

It is recommended to use low ESR capacitors to avoid loosing power during flash (it is also possible to connect two

capacitors in parallel to reduce ESR):

The rectification diode should have very low parasitic capacitance

5

and has to withstand the operating current and

reverse voltages.

Low ESR capacitors should be used to minimize VBAT 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 possible.

X5R dielectric material is recommended due to their ability to maintain capacitance over wide voltage and temperature

range.

If a different output capacitor is chosen, ensure low ESR values and voltage ratings.

Table 6. Recommended Photoflash Capacitors

Component

Part Number

Capacitor

Voltage

rating

Size

Manufacturer

330FW13A6.3X20

2x13.5µF

1

1. Different capacitor values are possible to be used together with the AS3635. Lower capacitor value will reduce

charging time, lower ESR capacitor will improve light output energy and reduce losses in the capacitor during

the flash pulse.

330V

Cylinder

2 x l=24mm,

d=7mm

Rubycon

www.rubycon.co.jp

5. A low parasitic capacitance improves charging efficiency.

Table 7. Recommended Rectification Diodes

Component

Part Number

Parasitic

Capacitor

Voltage

rating

Size

Manufacturer

FVO2R80

5pF

800V

1.25x2.5mm

Origin

www.origin.co.jp

GSD2004S

5pF / 2

2x240V

SOT-23

2.4x3.0mm

Vishay

www.vishay.com

BAS21

5pF / 2

2x250V

SC-70

2.0x2.1mm

OnSemi

www.onsemi.com

Table 8. Recommended

Component

Part Number

C

TC Code

Rated

Voltage

Size

Manufacturer

GRM155R60J474

470nF

X5R

6.3V

0402

Murata

www.murata.com

GRM155R60J105

GRM155R61A105

1µF

X5R

6.3V

10V

0402

GRM188R60J475

4.7µF

X5R

6.3V

0603