MP3356 – HIGH VOLTAGE PHOTO FLASH CHARGER AND IGBT DRIVER FOR DSC

MP3356 Rev. 0.91

www.MonolithicPower.com

8

1/29/2010

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OPERATION

The MP3356 controlled flyback charger operates

in critical conduction mode with 1.5A peak

current. The output voltage is divided down

through an internal 300: 1 resistive divider from

the

positive

terminal

of

the

transformer

secondary (FB pin) and compares it with an

internal 1.2V reference.

The low to high

transition of the EN pin will enable the flyback

converter to switch.

voltage is below 20V to avoid inrush current. The

boundary mode operation will follow to minimize

charge time when the output voltage is above

blanking for turn off transition. The circuit will stop

flash capacitor is charged to 300V. This value is

set by the internal 300:1 R divider and the 1.2V

reference. When charge is complete, the part will

shut down its internal circuitry and draw less than

100uA drawn from Vin. The EN pin will restart the

charge. Bringing the EN pin low terminates the

power delivery and puts the part in shutdown. A

a depleted battery. If the ON time exceeds the