The LT3420 and LT3420-1 are high efficiency photoflash capacitor chargers that charge a 220µF capacitor to 320V in 3.7 seconds or a 100µF capacitor to 320V in 3.5 seconds. This family uses standard transformers and features automatic refresh.
The LT3420/LT3420-1 are devices designed to charge high voltage photoflash capacitors quickly and efficiently using a flyback topology. They support operation from two AA cells or any supply ranging from 1.8V to 16V, making them suitable for digital and film camera flash units as well as high voltage power supplies.
These controllers feature controlled peak switch current (1.4A for LT3420, 1.0A for LT3420-1) and input current limits. They utilize an output voltage sensing scheme that monitors flyback voltage to regulate the output without requiring a discrete Zener diode or output resistor divider. The devices are available in 10-Lead MSOP and DFN packages.
| Charges 220uF to 320V time (LT3420) | 3.7 Seconds from 5V |
|---|---|
| Charges 100uF to 320V time (LT3420-1) | 3.5 Seconds from 5V |
| Controlled Peak Switch Current (LT3420) | 1.4A |
| Controlled Input Current (LT3420) | 840mA |
| Maximum Operating Voltage (Vcc) | 16 V |
The device achieves efficient flyback operation with a typical efficiency greater than 75%.
No, the design does not require a high voltage Zener diode.
The devices are available in 10-Lead MSOP and a small 10-Lead (3mm x 3mm) DFN package.