LT3420

VCC Voltage ........................................................... 16V
VBAT Voltage ............................................................ 16V
SW Voltage (Note 2)
LT3420 .................................................................... 38V
LT3420-1.................................................................. 50V
SEC Current ...................................................... ±200mA
RFB Current ........................................................... ±3mA
RREF Voltage ........................................................... 2.5V
CHARGE Voltage...................................................... 16V
CT Voltage .............................................................. 1.5V
DONE Voltage .......................................................... 16V
Current into DONE Pin .......................................... ±1mA
Maximum Junction Temperature .......................... 125°C
Operating Ambient Temperature Range
(Note 3) .............................................. 40°C to 85°C
Storage Temperature Range ................. 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C


Description

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 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.