Digital still cameras (DSC) have long used xenon flash as a light source. Now that mobile camera phones have become more full-featured and are including higher-resolution imaging systems, LED light sources are becoming more ineffective to the point that xenon is becoming the light source of choice if a flash is included in a given phone model.
The Allegro product portfolio of xenon photoflash charger ICs are designed to provide an ultra-small solution with flexibility to adjust both charging current limit and output voltage target. Most of Allegro’s devices use primary-side voltage sensing, eliminating the need for a secondary-side resistive voltage divider and its associated leakage and extra components. All devices use flyback technology and have an adjustable voltage.
The devices also integrate an IGBT driver, typically with internal gate resistors for minimum external component count. And most charge and trigger voltage logic thresholds are set to support applications implementing low-voltage control logic.
|Secondary Side Sensing|
|Part Number||Input Voltage||Output Current||Current Limit Selection||IGBT Driver||Packages|
|A8426||3 to 5.5 V
(1.5 to 11 Vbat)
|1 to 3.2 A||Analog||Independent source and sink noise immune interlock||3×3 mm TQFN-16|
|A8438||3 to 5.5 V (or 1.5 V min if Vcc supplied)||1.6 A, 1.8 A, 2 A||3-level pin selectable||Yes||3×3 mm TDFN-10|
|A8835||3 to 5.5 V||0.55 to 1.75 A||8-level serial interface||Independent source and sink noise immune interlock||3×3 mm TDFN-10|
The following xenon photoflash drivers have been discontinued: