DC661A-B - ANALOG DEVICES - Datasheet.Live

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

converter using the highly integrated

LT®3468ES5/LT®3468ES5-1 to rapidly charge a pho-

toflash capacitor up to 320V for photoflash applica-

tions. It demonstrates a simple application circuit op-

erating in high efficiency and shows appropriate lay-

out techniques for the LT3468ES5/LT3468ES5-1. The

circuit uses small surface mount components and

has very small board space compared to conventional

solutions.

This demonstration circuit is particularly useful for

applications such as camera flash, PDA and cell

phone flash and high voltage power supplies that re-

quire high efficiency and extremely small size.

Design files for this circuit board are available. Call

the LTC factory.

LT is a trademark of Linear Technology Corporation

Table 1.

Demo Board Assembly Versions

ASSEMBLY VERSIONS U1 ISW-PK (PEAK SWITCH CURRENT

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-

ate the performance of the LT3468ES5/LT3468ES5-1.

Refer to Figure 1 for proper measurement equipment

setup and follow the procedure below:

NOTE:

When measuring the input or output voltage

ripple, care must be taken to avoid a long ground lead

on the oscilloscope probe. Measure the input or out-

put voltage ripple by touching the probe tip directly

across the Vin or Vout and Gnd terminals. See Figure

2 for proper scope probe technique

NOTE:

For safe operation, always shield the circuit

when power is on, and always discharge the high

voltage output capacitor after power is off.

With power off, connect input power source Vin to

the Vin and Gnd terminals. Input voltage is limited

to 2.5V to 8V.

Connect second power source Vcharge to the

Charge and Gnd terminal. Input voltage is limited

to 2.5V to 8V.

Connect load (a 220uF, 350V photoflash capacitor)

between the +STROBE CAP and -STROBE CAP

terminals.

Slowly turn on power source Vin. Turn Vcharge on

to enable charge operation. Check for the proper

output voltages. Vout= 320V

NOTE:

If there is no output, temporarily disconnect

the load and make sure that Vcharge is applied to

Charge terminal.

For single source operation, connect Charge termi-

nal to Vin through an on/off switch. Turn on the

switch to enable charge operation.

Warning: Operate by high voltage trained personnel

only.