DC905A

DC905A demonstration circuit is a LED driver in SC70 with built-in Schottky featuring the LT3491. The LT3491 is a fixed frequency step-up current mode DC/DC converter. There are two circuits on demonstration board 905. The “small size” circuit generates 15mA LED current at the smallest possible solution size. The “high efficiency” circuit generates 20mA LED current at higher efficiency. The circuit outputs share 6 LEDs. At any given time, depending on the positions of jumpers, only one circuit is in operation. Other features of the LT3491, such as internal Schottky diode, the high switching frequency and the internal open circuit protection, a low tiny components for both circuits. The input range of the demo board is from 3V to 5V. Different dimming controls can be implemented on the demo board. Please refer to the quick start procedure. The high side current sensing feature of the LT3491 allows “one wire” current source, i.e. low side of the LED string can return to ground anywhere.

• 15mA (small size circuit) and 20mA (high efficiency circuit) typical output current
• 20.3V (small size circuit) and 20.6V (high efficiency circuit) typical output voltage
• 73.6% (VIN=4.2V, small size ckt) and 75.5% (VIN=4.2V, high efficiency circuit) typ efficiency
• 27V typical CAP pin overvoltage protection (LED open)
• 4mA maximum quiescent current at VIN=4.2V, CTRL=ON
• 10µA maximum quiescent current while in shutdown at VIN=4.2V, CTRL=OFF
• 2.3MHz typical switching frequency

Avisos

Do not look at operating LED. This circuit produces light that can damage eyes.