LT3468/LT3468-1

5

34681i

SW (Pin 1): Switch Pin. This is the collector of the internal

NPN Power switch. Minimize the metal trace area con-

nected to this pin to minimize EMI. Tie one side of the

primary of the transformer to this pin. The target output

voltage is set by the turns ratio of the transformer.

Choose Turns Ratio N by the following equation:

N

=

+ 2

31 5

.

You must tie a Schottky diode from GND to SW, with the

anode at GND for proper operation of the circuit. Please

refer to the applications section for further information.

GND (Pin 2): Ground. Tie directly to local ground plane.

DONE (Pin 3): Open NPN Collector Indication Pin. When

target output voltage is reached, NPN turns on. This pin

needs a pull-up resistor or current source.

CHARGE (Pin 4): Charge Pin. A low (<0.3V) to high (>1V)

transition on this pin puts the part into power delivery

mode. Once the target output voltage is reached, the part

will stop charging the output. Toggle this pin to start

charging again. Ground to shut down.

with a good quality ceramic capacitor. Input supply must

be 2.5V or higher.

PI FU CTIO S