QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 855 PHOTOFLASH CHARGER LT3484EDCB-0/LT3484EDCB-1/LT3484EDCB-2 DESCRIPTION Demonstration circuit 855 is a Photoflash Charger fea- quires no external Schottky diode clamp, reducing the turing the LT3484EDCB-0, LT3484EDCB-1, and solution size. The output voltage detection requires no LT3484EDCB-2. It demonstrates a complete photoflash external circuitry as the transformer turns ratio deter- application, including the photoflash capacitor, flash mines the final charger voltage. tube and trigger circuit. An on-board microcontrolller generates the necessary signals to produce an on- The device features a V pin, which allows the use of 2 demand flash, red-eye sequence, and flash capacitor BAT alkaline cells to charge the capacitor. The CHARGE pin refresh. gives full control of the part to the user. Driving CHARGE low shuts the part down. The demonstration board comes in three variants. DC855A-A uses the LT3484EDCB-0, while DC855A-B WARNING Lethal voltages are present on the DC855 and DC855A-C use the LT3484EDCB-1 and circuit board. Do not operate the assembly unless you LT3484EDCB-2, respectively. are trained to handle high voltage circuits. The LT3484 family of photoflash capacitor ICs is de- Design files for this circuit board are available. Call signed for use in a digital camera and mobile phone ap- the LTC factory. plications where space is a premium. The LT3484s pat- ented control technique allows it to use extremely small , LTC and LT are registered trademarks of Linear Technology Corporation. transformers, and the improved NPN power switch re- Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE Minimum V Voltage V = 2.8V 4.2V 1.8VDC BAT IN Maximum V Voltage V = 2.8V 4.2V 4.2VDC BAT IN Minimum V Voltage V = 1.8V 4.2V 2.8VDC IN BAT Maximum V Voltage V = 1.8V 4.2V 4.2VDC IN BAT Output Voltage V = 2.8V 4.2V, V = 1.8V 4.2V 320VDC, typical IN BAT Average input current DC855A-A, LT3484-0 500mA, typical DC855A-C, LT3484-2 350mA, typical DC855A-B, LT3484-1 225mA, typical 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 855 PHOTOFLASH CHARGER OPERATING PRINCIPLES The theory of operation of the LT3484 and xenon flash tube illumination has been discussed at length in the LT3484 data sheet and the Linear Technology Application Note AN95, respectively. The reader is referred to these documents, available online at