DC780B

DC780B is a demonstration circuit featuring LT®1618 constant-current constant voltage 1.4MHz step-up DC/DC converter. DC780B demonstrates a general purpose Boost converter with a 12V, 250mA output from a 3.3V to 4.2V source. The demo board can also be used as an LED driver, where a Luxeon LED (not installed), is driven with a regulated current of 500mA (default current), at a forward voltage of 3.5V. By changing the value or R4 to 2.2M the LED current can be regulated at 250mA. The LT1618 can be used for wider input voltages, but output voltage level and component selection restrict this demo circuit to Lithium Ion battery input levels.

• 100mV typ ripple at VIN = 3.3V, ILOAD = 250mA
• 83% typ efficiency at VIN = 4.2V, ILOAD = 250mA
• 1.4MHz typ switching frequency