Power Electronics

High-Efficiency Photoflash Capacitor Charger

Linear Technology’s new LT3468 is a high-efficiency, fast photoflash capacitor charger. The LT3468 is a standalone solution for photoflash capacitor charging, requiring minimum board area and no software development.

The LT3468 charges high-voltage (typically 320 V) photoflash capacitors quickly and efficiently. Intended for use in digital and film cameras, the device uses a current-limited flyback topology. It can charge a 100 uF capacitor to 320 V in 4.6 sec from a 3.6-V battery.

With a controlled peak current of 1.4 A, the LT3468, in conjunction with a standard flyback transformer, can charge any size photoflash capacitor with efficiencies greater than 80%. A unique switching control circuit has low loss through the entire charge cycle and eliminates the high inrush current typically found in flash modules.

The LT3468-1 is identical to the LT3468, except that current limit has been reduced to 0.7 A from 1.4 A. This reduced input current is needed for smaller batteries in applications such as cellular phone cameras.

Both the LT3468 and LT3468-1 use primary-side output voltage detection internal to the device. This eliminates the need for a resistor divider or discrete zener diodes and their power losses. Both are packaged in ThinSOT™ packages to ensure the minimal footprint/profile required in space constrained camera applications.

For more information, visit www.linear.com.

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