LT3485-0 Datasheet, PDF (1/20 Pages) Linear Technology – Photoflash Capacitor Chargers with Output Voltage Monitor and Integrated IGBT Drive

LT3485-0/LT3485-1/
LT3485-2/LT3485-3
Photoflash Capacitor
Chargers with Output Voltage
Monitor and Integrated IGBT Drive
FEATURES
■ _{Integrated IGBT Driver}
■ _{Voltage Output Monitor}
■ _{Uses Small Transformers: 5.8mm × 5.8mm × 3mm}
■ _{Operates from Two AA Batteries, Single Cell Li-Ion}
or Any Supply from 1.8V up to 10V
■ _{No Output Voltage Divider Needed}
■ _{No External Schottky Diode Required}
■ _{Charges Any Size Photoflash Capacitor}
■ _{Available in 10-Lead (3mm × 3mm) DFN}
Fast Charge Time
VERSION
INPUT CURRENT (mA)
LT3485-3
750
LT3485-0
500
LT3485-2
350
LT3485-1
225
V_IN = V_BAT = 3.6V
U ^{100µF capacitor, 320V. *50µF capacitor}
APPLICATIO S
CHARGE TIME (sec)
2.5
3.7
5.5
4.0*
■ _{Digital Camera and Cell Phone Flash Charger}
DESCRIPTIO
The LT^®3485 family of photoflash chargers are highly inte-
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
microcontroller from the monitor pin. Each device contains an
on-chip high voltage NPN power switch, which can withstand
negative voltages on the switch pin without an external
Schottky diode. The device features a V_BAT pin, which allows
the use of two AA cells to charge the capacitor. The internal
circuitry operates from the V_IN pin. The LT3485-0 has a
primary current limit of 1.4A, whereas the LT3485-3, 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.
, 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.
TYPICAL APPLICATIO
LT3485-0 Photoflash Charger Uses High Efficiency 3mm Tall Transformers
DANGER HIGH VOLTAGE – OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
V_BAT
2 AA OR
1 TO 2 Li-Ion
4.7µF
1:10.2
1• 4
2 _•5
V_BAT
SW
DONE
CHARGE
GND
LT3485-0
V_CC
5V
V_IN
V_MONT
0.22µF
IGBTPWR
TO
MICRO
320V
150µF
PHOTOFLASH
CAPACITOR
1M
2.2µF
600V
TRIGGER T
1
3
2
A
FLASHLAMP
C
IGBTIN IGBTOUT
IGBT
3485 TA01
LT3485-0 Charging Waveform
V_OUT
50V/DIV
AVERAGE
INPUT CURRENT
0.5A/DIV _{VIN = 3.6V}
C_OUT = 100µF
1s/DIV
3485 TA02
34850123fb
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