a8837 Allegro MicroSystems, Inc., a8837 Datasheet - Page 5

• Manufacturer Part Number: a8837
• Description: Photoflash Capacitor Charger With Igbt Driver
• Manufacturer: Allegro MicroSystems, Inc.

A8837
TRIGGER
IGBTDRV
CHARGE
Explanation of Events:
A.
B.
C. Start a new charging process with a low-to-high transition at the CHARGE pin.
D. Pull CHARGE to low, to put the controller in low-power standby mode.
E.
F.
DONE
V
SW
VIN
OUT
Start charging by pulling CHARGE to high, provided that V
Charging stops when V
completion of the charging process.
Charging does not start, because V
After V
required to start charging.
Target V
V
UVLO
OUT
IN
goes above V
A
TRIGGER
IGBTDRV
B
IGBT Drive Timing Definition
Operation Timing Diagram
UVLO
OUT
Photoflash Capacitor Charger with IGBT Driver
reaches the target voltage. ¯ D ¯ ¯ O ¯ ¯ N ¯ ¯ E ¯ goes low, to signal the
, another low-to-high transition at the CHARGE pin is
50%
t
10%
Dr
IN
C
90%
is below V
t
r
50%
UVLO
D
90%
t
Df
level when CHARGE goes high.
10%
t
f
IN
E
is above the V
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
F
UVLO
level.
5