LT3420-1

U U LT3420/LT3420-1 Photoflash Capacitor Chargers with Automatic Refresh FEATURES DESCRIPTIO ■ Charges 220µF to 320V in 3.7 Seconds from 5V (LT3420) ■ Charges 100µF to 320V in 3.5 Seconds from 5V (LT3420-1) ■ Charges Any Size Photoflash Capacitor ■ Supports Operation from Two AA Cells or Any Supply from 1.8V to 16V ■ Controlled Peak Switch Current: 1.4A (LT3420) 1.0A (LT3420-1) ■ Controlled Input Current: 840mA (LT3420) 450mA (LT3420-1) ■ Uses Standard Transformers ■ Efficient Flyback Operation (>75% Typical) ■ Adjustable Output ■ Automatic Refresh ■ Charge Complete Indicator ■ No High Voltage Zener Diode Required ■ No Output Voltage Divider Required ■ Small 10-Lead MSOP Package ■ Small 10-Lead (3mm × 3mm) DFN Package U APPLICATIO S ■ Digital Camera Flash Unit ■ Film Camera Flash Unit ■ High Voltage Power Supplies The LT®3420/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 t...