The LM3410 IC is a constant current LED driver useful in either boost con-verter or SEPIC design applications.
A SEPIC (Single Ended Primary Induct-ance Conver ter) design allows the power
supply’s output voltage to be set above, below or equal to its input voltage. In this application the chip is configured as a boost-converter (i.e. the output voltage is greater than the input voltage).
The LM3410 is available in two fixed-frequency variants. Using either the 525 kHz or 1.6 MHz clock version it is possi-ble to build a ver y compact LED driver. The output stage can supply up to 2.8 A, allowing several high-power LEDs to be driven from a rechargeable Lithium cell or several 1.5 V bat-teries.
The
chip also features a dimmer input giving simple PWM brightness control.Output current is defined by an external shunt resistor. To keep losses low the LM3410 uses an internal voltage reference of just 190 mV.
Power dissipation in the shunt resistor is therefore low. Using the desired value of LED current the value and power dissipation of the shunt resistor is given by:
R_Shunt = 0.19 V/I_LED
P_Shunt = 0.19 V*I_LED