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PDF A8437 Data sheet ( Hoja de datos )
| Número de pieza | A8437 | |
| Descripción | Mobile Phone Xenon Photoflash Capacitor Charger | |
| Fabricantes | Allegro MicroSystems | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de A8437 (archivo pdf) en la parte inferior de esta página. Total 22 Páginas | ||
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A8437
Mobile Phone Xenon Photoflash Capacitor Charger
with IGBT Driver
Discontinued Product
This device is no longer in production. The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: March 4, 2013
Recommended Substitutions:
For existing customer transition, and for new customers or new appli-
cations, contact Allegro Sales.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan
for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The
information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no respon-
sibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
1 page  
A8437
Mobile Phone Xenon Photoflash Capacitor Charger
with IGBT Driver
CG Package
A1 A2 A3 A4
B1 B2 B3 B4
C1 C2 C3 C4
Orientation mark
on ball side
Pin-out Diagrams
(Contacts Down Views)
EJ Package
ISET 1
10 REG
GATE 2
VIN 3
EP
9 DONE
8 TRIGGER1
GND 4
7 SW
CHARGE 5
6 TRIGGER2
Terminal List Table
Name
Number
CG EJ
ISET C4 1
GATE
GSOURCE
GSINK
VIN
GND
CHARGE
TRIGGER2
SW
TRIGGER1
–
B3
C3
C2
C1
B1
B2
A1
A2
2
–
–
3
4
5
6
7
8
¯D¯¯O¯¯N¯¯E¯
A3
9
TLIM
A4
–
REG
B4 10
EP n.a. –
Function
Sets the maximum switch current; connect an external resistor to GND to set the
desired peak current
IGBT gate drive – sink/source
IGBT gate drive – source
IGBT gate drive – sink
Input voltage; connect to a 2.3 to 5.5 V bias supply
Ground connection
Pull high to initiate charging; pull low to enter low-power standby mode
IGBT input trigger 2
Drain connection of internal power MOSFET switch; connect to transformer
IGBT input trigger 1
Pulls low when output reaches target value and CHARGE pin is high; goes high dur-
ing charging or whenever CHARGE pin is low
For production test only; connect to GND on PCB
Output voltage regulation pin; connect to external resistor and capacitor to regulate
output voltage, or connect to VIN pin to disable regulation (see Output Regulation
section for details)
Exposed pad for enhanced thermal dissipation; not connected electrically
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
5 Page 
A8437
Mobile Phone Xenon Photoflash Capacitor Charger
with IGBT Driver
by selecting the value of an external resistor RSET,
connected from the ISET pin to GND, which deter-
mines the ISET bias current, and therefore the switch-
ing current limit, ISWlim.
To the first order approximation, ISWlim is related to
ISET and RSET according to the following equations:
ISWlim = ISET × K = VSET / RSET × K ,
(3)
where K = 28000 when battery voltage is 3.6 V.
In real applications, the actual switching current
limit is affected by input battery voltage, and also the
transformer primary inductance, Lp. If necessary, the
following expressions can be used to determine ISWlim
more accurately:
ISET = VSET / (RSET + RSET(INT) – K × RGND(INT) ), (4)
where:
RSET(INT) is the internal resistance of the ISET pin
(1 kΩ typical),
RGND(INT) is the internal resistance of the bonding
wire for the GND pin (27 mΩ typical), and
K = (K′ + VIN × K″), with K′ = 24350 and K″ ≈
1040 at TA = 25°C. Then,
ISWlim = ISET × K + VBAT / LP × tD ,
(5)
where tD is the delay in SW turn-off (0.1 μs typical).
The chart at the bottom of the page can be used to
determine the relationship between RSET and ISWlim at
various battery voltages.
Peak Current Limit versus ISET Resistance
VIN = VBAT, XFM Lp = 8 μH, TA=25°C
1.3
1.2
1.1
VIN = 5.5 V
1.0 VIN = 4.5 V
0.9
VIN = 3.6 V
VIN = 3.0 V
0.8 VIN = 2.3 V
0.7
0.6
0.5
0.4
25 30 35 40 45 50 55 60 65 70 75 80 85 90
RSET (kΩ)
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet A8437.PDF ] | |
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