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ON Semiconductor has introduced a 4A supercapacitor LED flash driver.

The CAT3224 addresses the emerging requirements for high-intensity LED flash capability in high megapixel camera phones and stand-alone camera applications.

The device is integrated with all the functions necessary to accurately control LED flash charge/discharge, including power switches capable of sourcing up to 4A, as well as providing the charging function for dual-cell supercapacitors.

The CAT3224 uses three independent operational modes (charging, flash and torch) activated via a simple parallel logic interface.

The operating current of each mode is programmed by three external resistors.

High megapixel camera phones and stand-alone cameras require a very high-intensity flash to produce good quality photos, particularly in low or medium light conditions.

New LEDs on the market are designed to address this need.

However, the camera battery alone cannot deliver a high enough peak current pulse to drive the LED flash to the brightness levels required for high-resolution pictures.

The power issues are further exacerbated by the additional system functions that require high-peak current, such as zoom, auto focus, image capture, Class D audio and RF amplification.

The ON Semiconductor LED driver works in combination with the latest generation of supercapacitors to help designers eliminate these power management issues.

The supercapacitor discharges its power for peak-load functions and recharges continuously, even during the flash peaks.

The CAT3224 LED driver controls the supercapacitor charge to create additional energy for the other high-peak current circuits.

This supercapacitor LED driver design approach enables high-intensity flash and more system functionality while extending battery life.

The high-peak current benefits of supercapacitor technology, combined with the simple parallel logic interface of the CAT3224, also make the device a suitable choice for industrial applications where LEDs are being used to replace xenon-based lighting.

The CAT3224 supercapacitor LED driver supports three key functions: precise supercapacitor charging control, management of the current discharge into the LED flash, and constant current for LED torch mode.

The CAT3224 sources up to 4A LED flash pulses and up to 400mA torch-mode current, with simple programming via external resistors on the analogue control inputs.

The device incorporates a dual-mode 1x/2x charge pump, which charges the stacked supercapacitor to a nominal voltage of 5.4V, while an active balance control circuit ensures that both capacitor cell voltages are matched during the charging cycle.

In addition, the CAT3224 provides the user with a dedicated logic output to flag the completion of the supercapacitor charging sequence.

Packaged in a 16-lead TQFN 3mm x 3mm x 0.8mm package, the CAT3224 features thermal shutdown, over-voltage protection (OVP) and protection against external resistor programming faults.

The device also supports reverse output voltage for all conditions.

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