LT3420 - Photoflash Capacitor Chargers with Automatic Refresh
The LT3420/LT3420-1 charge high voltage photoflash capacitors quickly and efficiently. Designed for use in both digital and film cameras, these devices use a flyback topology to achieve efficiencies up to four times better than competing flash modules. A unique adaptive off-time control algorithm* maintains current-limited continuous mode transformer operation throughout the entire charge cycle, eliminating the high inrush current often found in modules.
The LT3420/LT3420-1 output voltage sensing scheme* monitors the flyback voltage to indirectly regulate the output voltage, eliminating an output resistor divider or discrete zener diode. This feature allows the capacitor to be held at a fully charged state without excessive power consumption. Automatic refresh (which can be defeated) allows the capacitor to remain charged while consuming an average input current of about 2mA, at a user-defined refresh rate. A logic high on the CHARGE pin initiates charging, while the DONE pin signals that the capacitor is fully charged.
The LT3420/LT3420-1 are available in 10-Lead MSOP and (3mm × 3mm) DFN packages.
*Protected by U.S. Patents including 6518733.
Features
Typical Application  | Applications
Packaging  |
Order Information
| Part Number | Package | Temp | Price(1-99) | Price (1k)* |
|---|---|---|---|---|
| LT3420EDD-1#PBF | 3x3 DFN-10 | E | $3.57 | $2.50 |
| LT3420EDD-1#TRPBF | 3x3 DFN-10 | E | $2.60 | |
| LT3420EDD#PBF | 3x3 DFN-10 | E | $3.57 | $2.50 |
| LT3420EDD#TRPBF | 3x3 DFN-10 | E | $2.60 | |
| LT3420EMS-1#PBF | MS-10 | E | $3.57 | $2.50 |
| LT3420EMS-1#TRPBF | MS-10 | E | $2.56 | |
| LT3420EMS#PBF | MS-10 | E | $3.57 | $2.50 |
| LT3420EMS#TRPBF | MS-10 | E | $2.56 |
Demo Boards
| Part Number | Description | Price |
|---|---|---|
| DC460A | LT3420EMS | Strobe Capacitor Charger, High Voltage Supply, 1.8V to 10V Input, 320Vout | $150.00 |
| DC646A | LT3420EMS | Strobe Capacitor Charger, High Voltage Supply, Input = 1.8V to 16V, Vout = 300V | $150.00 |
| DC690A | LT3420EMS-1 | Strobe Capacitor Charger, High Voltage Supply, Vbatt = 1.8V - 6V, Vcc = 2.3V - 6V, Strobe Cap = 320V | $125.00 |
- LT3420 Package Drawing LT3420
- DN303 - Photoflash Capacitor Charger Has Fast Efficient Charging and Low-Battery Drain
- R324 Reliability Data
- May 2002 LT3420 Charges Photoflash Capacitors Quickly and Efficiently While Using Minimal Board Space
- LT3420 Footprints and Symbols
- LT3420 Demo Circuit - High Charge Rate Strobe Capacitor Charger (2.5-6V to 320V)
