A8426EESTR-T Datasheet, PDF (1/16 Pages) Allegro MicroSystems – High Performance Photoflash Capacitor Charger with IGBT Driver

A8426
High Performance Photoflash Capacitor Charger
with IGBT Driver
Features and Benefits
▪ Wide battery voltage range: 1.5 to 11 V
▪ Integrated 55 V DMOS switch with 3.2 A current capability
▪ User-adjustable peak current limit, from 1 to 3.2 A
▪ Secondary-side voltage sensing for easily-adjustable
output voltage
▪ >75% efficiency
▪ Fast charging time
▪ Charge complete indication
▪ Flexible, high current IGBT driver
▫ Independent IGBT driver supply
▫ Separate sink and source pins with 6 Ω pull-up and
20 Ω pull-down
▫ Interlocked trigger pins improve noise immunity
▪ No primary-side Schottky diode needed
Package: 16-contact TQFN (suffix ES)
Description
The A8426 is a highly integrated IC that rapidly charges
photoflash capacitors for SLR cameras, digital cameras, and
camcorders with integrated digital cameras. A flexible IGBT
driver is integrated to save board space.
TheA8426 integrates a 3.2A-capable, 55V-rated DMOS switch
that drives the transformer in flyback configuration, allowing
optimized design with tight coupling and high efficiency. The
peak switch current is user-adjustable between 1 and 3.2 A,
using a resistor to ground. A proprietary control scheme
optimizes the capacitor charging time. Low quiescent current
and low-power Standby mode current further improve system
efficiency and extend battery life.
The A8426 is available in a 16-contact 3 mm × 3 mm TQFN
package with exposed pad for enhanced thermal performance.
This small, very thin profile (0.75 mm nominal overall height)
package is ideal for space-constrained applications. It is lead
(Pb) free, with 100% matte-tin leadframe plating.
Applications include:
▪ SLR camera flash
▪ Digital camcorder/DSC combo flash
▪ 2 Li+ input strobe
Approximate Scale 1:1
A8426-DS, Rev. 1
Typical Application
Bias Input
3.0 to 5.5 V
C2
Battery Input
1.5 to 11 V
VBAT
+
C1
1 : 10
VIN
TLIM
SW
ISET
RSET
Control
Block
I_SW sense
FB
COUT
100 μF
330 V
R1
150 k7
R2
150 k7
CHARGE
DONE
VPULLUP
100 kΩ
R3
1.20 k7
TRIGGER1
VDRV
IGBT Driver
DONE
GSOURCE
IGBT Gate
TRIGGER2
GND
GSINK
Figure 1. Typical application circuit with resistor bridge control of feedback.