Final Electrical Specifications
LT3468/LT3468-1
Photoflash Capacitor
Charger in ThinSOT
TM
October 2003
FEATURES
s
s
DESCRIPTIO
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s
s
s
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s
Highly Integrated IC Reduces Solution Size
Uses Small Transformers:
5.8mm
脳
5.8mm
脳
3mm
Fast Photoflash Charge Times:
4.6s for LT3468 (0V to 320V, 100碌F, V
IN
= 3.6V)
5.5s for LT3468-1 (0V to 320V, 50碌F, V
IN
= 3.6V)
Controlled Input Current:
500mA (LT3468)
225mA (LT3468-1)
Supports Operation from Single Li-Ion Cell, or Any
Supply from 2.5V up to 16V
Adjustable Output Voltage
No Output Voltage Divider Needed
Charges Any Size Photoflash Capacitor
Low Profile (1mm) SOT-23 Package
The LT
廬
3468/LT3468-1 are highly integrated ICs designed
to charge photoflash capacitors in digital and film cam-
eras. A new control technique* allows for the use of
extremely small transformers. Each device contains an
on-chip high voltage NPN power switch. Output voltage
detection* is completely contained within the device,
eliminating the need for any discrete zener diodes or
resistors. The output voltage can be adjusted by simply
changing the turns ratio of the transformer. The LT3468
has a primary current limit of 1.4A while the LT3468-1 has
a 0.7A limit. These different current limit levels result in
well controlled input currents of 500mA for the LT3468
and 225mA for the LT3468-1. Aside from the differing
current limit, the two devices are otherwise equivalent.
The CHARGE pin gives full control of the part to the user.
Driving CHARGE low puts the part in shutdown. The DONE
pin indicates when the part has completed charging. The
LT3468 series of parts are housed in tiny low profile
(1mm) SOT-23 packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation. *U.S. Patent # 6, 518, 733
APPLICATIO S
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Digital / Film Camera Flash
PDA / Cell Phone Flash
Emergency Strobe
TYPICAL APPLICATIO S
DANGER HIGH VOLTAGE 鈥?OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
VIN
2.5V TO 8V
T1
1:10.2
C1
4.7碌F
1
2
4
5
D1
320V
VIN
2.5V TO 8V
C1
4.7碌F
+
R1
100k
DONE
CHARGE
V
IN
LT3468
DONE
CHARGE
GND
SW
D2
COUT
PHOTOFLASH
CAPACITOR
R1
100k
DONE
CHARGE
V
IN
LT3468-1
DONE
GND
CHARGE
C1: 4.7碌F, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6-1, L
PRI
= 10碌H, N = 10.2
D1: VISHAY GSD2004S DUAL DIODE CONNECTED IN SERIES
D2: ZETEX ZHCS400 OR EQUIVALENT
R1: PULL UP RESISTOR NEEDED IF DONE PIN USED
3468 TA01
C1: 4.7碌F, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6S-1, L
PRI
= 24碌H, N = 10.2
D1: VISHAY GSD2004S DUAL DIODE CONNECTED IN SERIES
D2: ZETEX ZHCS400 OR EQUIVALENT
R1: PULL UP RESISTOR NEEDED IF DONE PIN USED
Figure 1. LT3468 Photoflash Charger Uses
High Efficiency 4mm Tall Transformer
Figure 2. LT3468-1 Photoflash Charger Uses
High Efficiency 3mm Tall Transformer
34681i
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
T1
1:10.2
4
3
5
6
D1
320V
U
U
+
SW
D2
COUT
PHOTOFLASH
CAPACITOR
3468 TA02
1
1
2
3
4
5
6
7
8
9
10
11
12
