a8735 Allegro MicroSystems, Inc., a8735 Datasheet - Page 8

• Manufacturer Part Number: a8735
• Description: Ultra Small Mobile Phone Xenon Photoflash Capacitor Charger With Igbt Driver
• Manufacturer: Allegro MicroSystems, Inc.

A8735
Note: Output voltage is sensed from the primary side winding when the switch turns off. This duration, t
to be long enough (>200 ns) in order to obtain an accurate measurement. The value of t
primary inductance, L
Transformer L
Transformer L
0.50
0.45
0.40
0.35
0.30
0.25
0.20
328
327
326
325
324
323
322
321
320
1.5
1.5
Average Input Current versus Battery Voltage
Final Output Voltage versus Battery Voltage
Primary
2.0
2.0
Ultra Small Mobile Phone Xenon Photoflash
PRIMARY
PRIMARY
, and the turns ratio, N, as given by: t
2.5
2.5
= 12.8 μH, N =10.25, V
= 12.8 μH, N =10.25, V
3.0
3.0
Battery Voltage (V)
Battery Voltage (V)
Capacitor Charger with IGBT Driver
3.5
3.5
4.0
4.0
IN
IN
=3.6 V, at room temperature
=3.6 V, at room temperature
4.5
4.5
off
= (I
5.0
5.0
SWlim
× L
5.5
5.5
PRIMARY
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
off
× N) / V
depends on I
OUT
.
off
SWlim
, has
,
8