DC661A-B Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 661 PHOTOFLASH CAPACITOR CHARGER, HIGH VOLTAGE SUPPLY LT3468ES5/LT3468ES5-1 DESCRIPTION Demonstration circuit 661 is a DC/DC flyback This demonstration circuit is particularly useful for converter using the highly integrated applications such as camera flash, PDA and cell LT 3468ES5/LT 3468ES5-1 to rapidly charge a pho- phone flash and high voltage power supplies that re- toflash capacitor up to 320V for photoflash applica- quire high efficiency and extremely small size. tions. It demonstrates a simple application circuit op- erating in high efficiency and shows appropriate lay- Design files for this circuit board are available. Call out techniques for the LT3468ES5/LT3468ES5-1. The the LTC factory. circuit uses small surface mount components and has very small board space compared to conventional LT is a trademark of Linear Technology Corporation solutions. Table 1. Demo Board Assembly Versions ASSEMBLY VERSIONS U1 I (PEAK SWITCH CURRENT SW-PK LIMIT) DC661A-A LT3468ES5 1.4A DC661A-B LT3468ES5-1 0.6A QUICK START PROCEDURE Demonstration circuit 661 is easy to set up to evalu- 2. Connect second power source Vcharge to the ate the performance of the LT3468ES5/LT3468ES5-1. Charge and Gnd terminal. Input voltage is limited Refer to Figure 1 for proper measurement equipment to 2.5V to 8V. setup and follow the procedure below: 3. Connect load (a 220uF, 350V photoflash capacitor) NOTE: When measuring the input or output voltage between the +STROBE CAP and -STROBE CAP ripple, care must be taken to avoid a long ground lead terminals. on the oscilloscope probe. Measure the input or out- 4. Slowly turn on power source Vin. Turn Vcharge on put voltage ripple by touching the probe tip directly to enable charge operation. Check for the proper across the Vin or Vout and Gnd terminals. See Figure output voltages. Vout= 320V 2 for proper scope probe technique NOTE: If there is no output, temporarily disconnect NOTE: For safe operation, always shield the circuit the load and make sure that Vcharge is applied to when power is on, and always discharge the high Charge terminal. voltage output capacitor after power is off. 5. For single source operation, connect Charge termi- 1. With power off, connect input power source Vin to nal to Vin through an on/off switch. Turn on the the Vin and Gnd terminals. Input voltage is limited switch to enable charge operation. to 2.5V to 8V. Warning: Operate by high voltage trained personnel only. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 661 PHOTOFLASH CAPACITOR CHARGER, HIGH VOLTAGE SUPPLY Figure 1. Proper Measurement Equipment Setup Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2