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. Applications * Digital Camera Flash Unit * Film Camera Flash Unit * High Voltage Power Supplies * 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 https://elecena.pl/product/246505/photoflash-capacitor-chargers-with-automatic-refresh 2007-03-01 https://elecena.pl/product/246505/photoflash-capacitor-chargers-with-automatic-refresh 2014-06-12 https://elecena.pl/product/246505/photoflash-capacitor-chargers-with-automatic-refresh 2025-01-20