DC1224A: 40V @ 20mA, 3 ~ 5V in, Boost

Demonstration circuit 1224 is a LED Driver with One Wire Control and Output Disconnect featuring the LT3593. The LT3593 is a step-up current mode DC/DC converter designed to drive up to 10 white LEDs in series from a Li-Ion cell. The demo board has two sections. The top section showcases the small size LED drive. The maximum current is 20mA. The bottom section is the control section that generates pulses for the CTRL pin of the LED driver. The number of pulses and its timing determine the current and brightness of the LEDs.

The LCD display in the bottom section shows the status of the commanding LED current level in the format as “LEVEL=value” and LED current level as “ILED=value”. The LEVEL value responses to the UP button SW1 and DOWN button SW2 immediately. The ILED value only changes to the commanding LEVEL value after the SEND/STORE button SW3 is pushed. Pushing SEND/STORE button also save the LEVEL value in the memory of the micro-controller U2 as the default LED current level.

The LT3593 datasheet gives complete description of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for working on or modifying the demo circuit 1224.