LT3468_15 Datasheet, PDF (1/12 Pages) Linear Technology – Photoflash Capacitor Chargers in ThinSOT

LT3468/LT3468-1/LT3468-2
Photoflash Capacitor
Chargers in ThinSOT^TM
FEATURES
■ _{Highly Integrated IC Reduces Solution Size}
■ _{Uses Small Transformers:}
5.8mm × 5.8mm × 3mm
■ _{Fast Photoflash Charge Times:}
4.6s for LT3468 (0V to 320V, 100µF, V_IN = 3.6V)
5.7s for LT3468-2 (0V to 320V, 100µF, V_IN = 3.6V)
5.5s for LT3468-1 (0V to 320V, 50µF, V_IN = 3.6V)
■ _{Controlled Input Current:}
500mA (LT3468)
375mA (LT3468-2)
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}
U
APPLICATIO S
■ _{Digital / Film Camera Flash}
■ _{PDA / Cell Phone Flash}
■ _{Emergency Strobe}
DESCRIPTIO
The LT^®3468/LT3468-1/LT3468-2 are highly integrated
ICs designed to charge photoflash capacitors in digital and
film cameras. A patented 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, the LT3468-2 has a 1A
limit, and the LT3468-1 has a 0.7A limit. These different
current limit levels result in well controlled input currents
of 500mA for the LT3468, 375mA for the LT3468-2 and
225mA for the LT3468-1. Aside from the differing current
limit, the three 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 available 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.
All other trademarks are the property of their respective owners.
*Protected by U.S. Patents, including 6518733.
TYPICAL APPLICATIO
LT3468 Photoflash Charger Uses
High Efficiency 4mm Tall Transformer
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE
TRAINED PERSONNEL ONLY
VIN
2.5V TO 8V
4.7µF
1:10.2
1
4
2
5
320V
+
100µF
100k
DONE
V_IN
SW
LT3468
DONE
GND
CHARGE
CHARGE
346812 TA01
LT3468 Charging Waveform
V_IN = 3.6V
C_OUT = 100µF
V_OUT
50V/DIV
AVERAGE
INPUT
CURRENT
1A/DIV
1s/DIV
3468 G01
346812fa
1