Description

The Allegro®A8437 Xenon photoflash charger IC is designed to meet the needs of ultra-low power, small form factor cameras, particularly camera-phones.

The charge current time is adjustable by setting the charge current limit from 0.4 to 1.2 A maximum. By using primaryside voltage sensing, the need for a secondary-side resistive voltage divider is eliminated. This has the additional benefit of reducing leakage currents on the secondary side of the transformer. To extend battery life, the A8437 features very low supply current draw—typically 0.1 μA in shutdown mode and 10 μA in standby mode.

Features and Benefits

▪ Low quiescent current draw (0.1 μA in shutdown mode)

▪ Primary-side output voltage sensing; no resistor divider

required

▪ User-adjustable current limit from 0.4 to 1.2 A

▪ 1.1 V logic (VHI(min)) compatibility

▪ Integrated IGBT driver with separate sink and source (CG

package) or common sink/source (EJ package)

▪ Flash dual trigger with interlock for increased noise

immunity

▪ Optimized for mobile phone, 1-cell Li+ battery applications

▪ No primary-side Schottky diode needed

▪ Zero-voltage switching for lower loss

▪ >75 efficiency

▪ Optional regulation feature to maintain the output voltage

▪ Charge complete indication

▪ Integrated 40 V DMOS switch