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Allegro MicroSystems

A8439 Datasheet Preview

A8439 Datasheet

Photoflash Capacitor Charger

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A8439
Photoflash Capacitor Charger
with IGBT Driver and Refresh
Features and Benefits
Power with 1 Li+ or 2 Alkaline/NiMH/NiCAD batteries
Adjustable output voltage
Auto-refresh
>75% efficiency
Eight-level, digitally-programmable current limit
Charge complete indication
Integrated IGBT driver with trigger
No primary-side Schottky diode needed
Low-profile package (0.75 mm nominal height)
Package: 10 pin TDFN/MLP (suffix EJ)
Approximate Scale
Description
The A8439 is a highly integrated IC that charges photoflash
capacitors for digital and film cameras.An integrated MOSFET
switch drives the transformer in a flyback topology. It also
features an integrated IGBT driver that facilitates the flash
discharge function and saves board space.
The CHARGE pin enables the A8439 and starts the charging
of the output capacitor. When the designated output voltage is
reached, the A8439 stops the charging until the CHARGE pin
is toggled again, or when output voltage falls below 90% of
the designated value. Pulling the CHARGE pin low stops the
charging. The D¯¯O¯¯N¯¯E¯¯ pin is an open-drain indicator of when
the designated output voltage is reached.
The peak current limit can be adjusted to eight different levels
between 270 mA and 1.4 A, by clocking the CHARGE pin.
This allows the user to operate the flash even at low battery
voltages.
TheA8439 can be used with twoAlkaline/NiMH/NiCAD or one
single-cell Li+ battery connected to the transformer primary.
Connect the VIN pin to a 3.0 to 5.5 V supply, which can be
either the system rail or the Li+ battery, if used.
The A8439 is available in a very low profile (0.75 mm) 10-
terminal 3×3 mm MLP/TDFN package, making it ideal for
space-constrained applications. It is lead (Pb) free, with 100%
matte-tin leadframe plating.
Applications include the following:
Digital camera flash
Film camera flash
Cell phone flash
Emergency strobe light
Typical Applications
VBIAS 3.0 to 5.5 V
Two Alkaline/NiMH/NiCAD or one Li+ battery
or 1.5 to 5.5 V
VBATT
T1 D1
VOUT
One Li+ battery
VBATT or 3.0 to 5.5 V
T1 D1
R4
100 k7
C1
0.1 μF
C2
4.7 μF
R5
10 k7
VIN
CHARGE
DONE
SW
FB
A8439
TRIGGER
IGBTDRV
R6
10 k7
GND
To IGBT Gate
R1 COUT
R2
R3 C3
R4
100 k7
C1
0.1 μF
C2
4.7 μF
R5
10 k7
VIN
CHARGE
DONE
SW
FB
A8439
TRIGGER
IGBTDRV
R6
10 k7
GND
To IGBT Gate
R1
R2
R3
VOUT
COUT
C3
Figure 1. Typical circuit with separate power supply to transformer
A8439-DS, Rev. 5
Figure 2. Typical circuit with single power supply




Allegro MicroSystems

A8439 Datasheet Preview

A8439 Datasheet

Photoflash Capacitor Charger

No Preview Available !

A8439
Photoflash Capacitor Charger with IGBT Driver and Refresh
Selection Guide
Part Number
A8439EEJTR-T
Package
10-pin TDFN/MLP
*Contact Allegro for additional packing options
Packing*
1500 pieces/ 7-in. reel
Absolute Maximum Ratings
Characteristic
SW pin
IGBTDRV pin
FB pin
All other pins
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
VSW
VIGBTDRV
VFB
VX
TA
TJ(max)
Tstg
Range E
Notes
Rating
–0.3 to 40
–0.3 to VIN + 0.3
–0.3 to VIN
–0.3 to 7
–40 to 85
150
–55 to 150
Units
V
V
V
V
ºC
ºC
ºC
Package Thermal Characteristics
Characteristic
Symbol
Test Conditions*
Package Thermal Resistance
RθJA 4layer PCB, based on JEDEC standard
*Additional information is available on the Allegro website.
Rating Units
45 ºC/W
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com


Part Number A8439
Description Photoflash Capacitor Charger
Maker Allegro MicroSystems
Total Page 14 Pages
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