Photoflash capacitor charger adds output voltage monitor, integrated IGBT driver - Embedded.com

Photoflash capacitor charger adds output voltage monitor, integrated IGBT driver

The LT3485 family of photoflash capacitor charger ICs from Linear Technology integrate a complete photoflash capacitor charger and IGBT drive. The part's control technique allows it to use small standard transformers. No external components are required to set the output voltage. While charging, an output proportional to the capacitor voltage is available for monitoring. Input current is tightly controlled to provide consistent charge time.

The devices operate from an input voltage of 1.8 to 10 V, making them suitable for applications powered by two AA alkaline cells or Li-Ion single or multiple cell batteries. The LT3485-3, -0, -2 and -1 have primary current limits of 2, 1.4, 1 and 0.7 A, respectively, resulting in average input currents of 700, 500, 350, and 225 mA, respectively. The four versions are otherwise identical.

The Charge pin gives the user full control of the part. Driving this pin low puts the part in extremely low power shutdown mode. A Done pin indicates when the part has completed charging. The chargers are housed in a low-profile 3- by 3-mm DFN packages. In 1000-piece quantities, the parts sell for $2.25 each. More information is available at www.linear.com.

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