LM3410 IC: Versatile Constant Current LED Driver
Adaptable Design Possibilities
The LM3410 IC is a versatile constant current LED driver that finds utility in both boost converter and SEPIC design applications. Its flexibility is highlighted in Single Ended Primary Inductance Converter (SEPIC) designs, which enable the power supply’s output voltage to be configured above, below, or equal to its input voltage. In the specific configuration discussed here, the chip operates as a boost converter, indicating that the output voltage surpasses the input voltage.
Versatile and Compact LED Driver with LM3410
Multiple Frequency Variants for Compact Design
The LM3410 LED driver offers flexibility through two fixed frequency options: 525 kHz or 1.6 MHz. These variants allow the construction of highly compact LED drivers. With an output stage capable of delivering up to 2.8 A, this driver empowers the illumination of multiple high-power LEDs. It’s suitable for various power sources, including rechargeable Lithium cells or configurations involving several 1.5 V batteries. Additionally, the LM3410 integrates a dimmer input, enabling straightforward PWM-based brightness control.
Precise Output Control and Low Power Dissipation
The output current of the LM3410 is determined by an external shunt resistor, ensuring precise control. Remarkably, the LM3410 minimizes losses by utilizing an internal voltage reference of a mere 190 mV. Consequently, power dissipation in the shunt resistor remains exceptionally low. To calculate the appropriate value and power dissipation of the shunt resistor based on the desired LED current, specific formulas are utilized, ensuring efficient and controlled illumination.
R_Shunt = 0.19 V/I_LED
P_Shunt = 0.19 V*I_LED
A 10 µH coil (L1) will be sufficient for most applications providing it has a suitable saturation current rating. The Input and output capacitors should be 10 µF ceramic types with a low value of ESR. Many distributors including Farnell stock these components. The Diode should be a Schottky type (as in all switching regulators). The author has developed a PCB for this design; the corresponding Eagle files can be freely downloaded from www.elektor.com/090850. In summary, the most important features of the LM3410 are:
- Integrated 2.8 A MOSFET driver
- Input voltage range from 2.7 V to 5.5 V
- Capability to drive up to six series connected
- LEDs (maximum output 24 V).
- Up to 88 % efficiency.
- Available is 525 kHz and 1.6 MHz versions.
- Allows both boost and SEPIC designs.
- Available in 5 pin SOT23 or 6 pin LLP outline.