LED闪光灯设计LEDs for Strobe Lights Application Note Introduction Often, the light available for taking a photograph is insufficient, requiring the use of a flash unit as an additional light source. Traditional flash units consist of a flash tube in which a flash is created by means of a gas discharge. The flash tube contains an inert gas, usually xenon or krypton. Using a suitable circuit the battery charges a capacitor to a level of a few hundred volts, which is then stepped up to a secondary voltage in the kV range by means of an ignition coil. This ignition voltage is released in the flash tube, causing the gas to ionize. The flash arises through recombination, and lasts a few milliseconds. During this time, a few hundred Amperes of current flow. The light emitted from the flash tube exhibits a con……