LT3485-0/LT3485-1/

LT3485-2/LT3485-3

1

34850123fb

FEATURES

DESCRIPTIO

Photoflash Capacitor

Chargers with Output Voltage

Monitor and Integrated IGBT Drive

TYPICAL APPLICATIO

■

Integrated IGBT Driver

× 5.8mm × 3mm

■

Operates from Two AA Batteries, Single Cell Li-Ion

or Any Supply from 1.8V up to 10V

■

No External Schottky Diode Required

× 3mm) DFN

APPLICATIO S

The LT

grated ICs containing complete charger and IGBT drive

functions. The patented control technique of the LT3485-x

allows it to use extremely small transformers. Output voltage

detection requires no external circuitry. The turns ratio of the

transformer controls the final charge voltage. While charging,

the output voltage on the capacitor may be monitored by a

microcontrollerfromthemonitorpin.Eachdevicecontainsan

on-chip high voltage NPN power switch, which can withstand

negative voltages on the switch pin without an external

the use of two AA cells to charge the capacitor. The internal

primarycurrentlimitof1.4A,whereastheLT3485-3,LT3485-2,

and LT3485-1 have current limits of 2A, 1A and 0.7A respec-

tively. These different current limits result in tightly controlled

input currents.

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 LT3485

series of parts are housed in a leadless (3mm

× 3mm) DFN

package.

Fast Charge Time

VERSION

INPUT CURRENT (mA)

CHARGE TIME (sec)

LT3485-3

750

2.5

LT3485-0

500

3.7

LT3485-2

350

5.5

LT3485-1

225

4.0*

100

µF capacitor, 320V. *50µF capacitor

LT3485-0

IGBTOUT

IGBTIN

IGBTPWR

GND

SW

4.7

µF

1:10.2

•

•

2 AA OR

1 TO 2 Li-Ion

0.22

µF

5V

320V

TO

MICRO

1

T

C

A

2

3

1

2

4

5

3485 TA01

150

µF

PHOTOFLASH

CAPACITOR

2.2

µF

600V

1M

CHARGE

DONE

TRIGGER

FLASHLAMP

IGBT

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Protected by U.S. Patents including 6636021.

LT3485-0 Charging Waveform

LT3485-0 Photoflash Charger Uses High Efficiency 3mm Tall Transformers

DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY

50V/DIV

AVERAGE

INPUT CURRENT

0.5A/DIV

1s/DIV

3485 TA02