FEATURES
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LT3585-0/LT3585-1
LT3585-2/LT3585-3
Photoflash Chargers with
Adjustable Input Current
and IGBT Drivers
DESCRIPTIO
The LT
®
3585 series are highly integrated ICs designed to
charge photoflash capacitors in digital and film cameras.
A new control technique allows for the use of extremely
small transformers. Each part contains an on-chip high
voltage NPN power switch. Output voltage detection is
completely contained within the part, eliminating the need
for any discrete zener diodes or resistors. The output volt-
age can be adjusted by simply changing the turns ratio
of the transformer.
The CHRG/IADJ pin gives full control of the part to the
user. Driving CHRG/IADJ low puts the part in low power
shutdown. The CHRG/IADJ pin can also be used to reduce
the input current of the charger, useful in extending battery
life. The DONE pin indicates when the part has completed
charging.
The LT3585 series of parts are housed in tiny 3mm
×
2mm DFN packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Adjustable Input Current
Integrated IGBT Driver
No Output Voltage Divider Needed
Uses Small Transformers: 5.8mm
×
5.8mm
×
3mm
Fast Photoflash Charge Times
Charges Any Size Photoflash Capacitor
Supports Operation from Single Li-Ion Cell, Two AA
Cells or any Supply from 1.5V Up to 16V
Small 10-Lead (3mm
×
2mm) DFN Package
REDUCED MODE
CHARGE TIME
(Sec)
6.6
9.2
12.6
14.6
Fast Charge Time
NORMAL MODE
INPUT
CHARGE TIME
VERSION
CURRENT (mA)
(Sec)
LT3585-3
800/400
3.3
LT3585-0
550/275
4.6
LT3585-2
400/200
5.8
LT3585-1*
250/115
5.0
100µF capacitor, 320V, V
IN
= V
BAT
= 3.6V
*50µF capacitor, 320V, V
IN
= V
BAT
= 3.6V
APPLICATIO S
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Digital/Film Camera Flash
PDA/Cell Phone Flash
Emergency Strobe
TYPICAL APPLICATIO
LT3585-1 Photoflash Charger Uses High Efficiency
2mm Tall Transformers with Tunable IGBT Gate Drive
DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
V
BAT
2 AA OR
1 TO 2 Li-Ion
1:10:2
4.7µF
1
320V
4
1M
•
2
V
BAT
DONE
V
IN
5V
0.22µF
CHRG/IADJ
LT3585-1
V
IN
IGBTPWR
IGBTIN
IGBTPU
IGBTPD
SW
GND
•
5
+
50µF
PHOTOFLASH
CAPACITOR
2.2µF
600V
TRIGGER T
1
3
2
A
V
OUT
50V/DIV
FLASHLAMP
C
I
IN
500mA/DIV
TO GATE OF IGBT
20Ω TO
160Ω
3585 TA01a
U
U
U
LT3585-1 Charging Waveform
Normal Input Current Mode
V
BAT
= 3.6V
C
OUT
= 50µF
1sec/DIV
3585 TA01b
3585f
1
LINER [ LINEAR TECHNOLOGY ]
