IGBT FOR CAMERA WITH FLASH

Most consumers have already migrated from taking photographs using film to a digital medium. The Digital Still Camera (DSC) has now become common-place. All digital cameras incorporate a flash with many features such as red eye reduction. These capabilities require a digitally programmable control with very compact circuitry to drive the Xenon flash. Some cell-phones now incorporate a flash to improve up on the quality of photographs taken under low light conditions. In addition, electronic control of lighting is used by professional photographers with strobe flashes. Lighting rumors states on their website: “Paul C. Buff’s Einstein monolights have been a big hit in the photographic lighting market, much lauded for their insulated-gate bipolartransistor (IGBT) circuitry and digital remote control.”

A Xenon bulb is used to create a short powerful burst of light with illumination characteristics close to that of sunlight. The Xenon bulb requires a high operating voltage of 320-V derived from a low 3 to 6 volt battery source. This is achieved by using a DC/DC converter with step-up transformer as shown in the figure. The high voltage is stored in a capacitor and discharged into the Xenon blub by turning on the IGBT. The IGBTs must have not only a high sustaining voltage capability but must be capable of operating with a drive voltage of only 4 volts. The footprint of the IGBT must also be reduced with innovative chip design and packaging because it must be capable of handling 150-A for a short duration. A similar circuit is used for the flash in a cell-phone but there is even greater pressure for IGBT manufacturers to reduce the foot-print and gate drive voltage. Some companies have described their technology roadmap for shrinking the footprint for the IGBT devices used for the flash application.