LT3468 Datasheet, PDF (1/12 Pages) Linear Technology – Photoflash Capacitor Charger in ThinSOT

FEATURES
s _{Highly Integrated IC Reduces Solution Size}
s _{Uses Small Transformers:}
5.8mm × 5.8mm × 3mm
s _{Fast Photoflash Charge Times:}
4.6s for LT3468 (0V to 320V, 100µF, V_IN = 3.6V)
5.5s for LT3468-1 (0V to 320V, 50µF, V_IN = 3.6V)
s _{Controlled Input Current:}
500mA (LT3468)
225mA (LT3468-1)
s _{Supports Operation from Single Li-Ion Cell, or Any}
Supply from 2.5V up to 16V
s _{Adjustable Output Voltage}
s _{No Output Voltage Divider Needed}
s _{Charges Any Size Photoflash Capacitor}
s _{Low Profile (1mm) SOT-23 Package}
U
APPLICATIO S
s _{Digital / Film Camera Flash}
s _{PDA / Cell Phone Flash}
s _{Emergency Strobe}
Final Electrical Specifications
LT3468/LT3468-1
Photoflash Capacitor
Charger in ThinSOT^TM
October 2003
DESCRIPTIO
The LT^®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
TYPICAL APPLICATIO S
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
VIN
2.5V TO 8V
C1
4.7µF
T1
1:10.2
D1
1
4
2
5
+
R1
V_IN
SW
D2
100k
LT3468
DONE
DONE
GND
320V
COUT
PHOTOFLASH
CAPACITOR
VIN
2.5V TO 8V
C1
4.7µF
T1
1:10.2
D1
4
5
3
6
+
R1
V_IN
SW
D2
100k
LT3468-1
DONE
DONE
GND
320V
COUT
PHOTOFLASH
CAPACITOR
CHARGE
CHARGE
CHARGE
CHARGE
C1: 4.7µF, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6-1, L_PRI = 10µH, 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
3468 TA01
C1: 4.7µF, X5R OR X7R, 10V
T1: KIJIMA MUSEN PART# SBL-5.6S-1, L_PRI = 24µH, 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 2. LT3468-1 Photoflash Charger Uses
High Efficiency 3mm Tall Transformer
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.
3468 TA02
34681i
1