MP3361 datasheet(6/7 Pages) MPS

6 / 7 page

MP3361 – 300V, 1A PEAK INTEGRATED PHOTO FLASH CHARGER AND IGBT DRIVER

MP3361 Rev. 0.9

www.MonolithicPower.com

4/13/2010

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

OPERATION

The MP3361 controlled flyback charger operates

in critical conduction mode. 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 CHG pin will enable the flyback

converter to switch.

A constant TOFF of 20μs is used when the output

voltage is below 20V to avoid inrush current. The

boundary mode operation will follow to minimize

charge time when the output voltage is above

20V. A minimum TOFF of 200ns serves as

blanking for turn off transition. The circuit will stop

switching and RDYB will be pulled low once the

flash capacitor is charged to 300V, a value set by

the internal 300:1 R divider and 1.2V reference.

When the charge is full, the part will shut down its

internal circuitry with less than 1uA drawn from

VIN. Toggling the CHG pin will start the charge

cycle again. Bringing CHG pin low terminates the

power delivery and puts the part in shutdown. A

maximum TON timer prevents pulling current from

a depleted battery.

If the ON time exceeds

maximum TON, the switch is forced OFF

regardless of IPEAK detection.

MP3361 Datasheet(PDF) 6 Page - Monolithic Power Systems