Electronic – Ideal component to switch 84V DC


I wanted to control a 84V LED strip using a ATtiny13a microcontroller with minimal power wasted. I just want to turn it on and off, don't need any PWM dimming. The strip uses 270mA current and is about 22W power. MCU will be getting around 5V and 10-15mA supply and MCU uses only about 3-4mA max.

I have 3 components for this but I don't know which will waste least power as heat.I have IRL540N Logic level Mosfet , TIP122 Darlington power transistor and BT169D Thryistor/SCR. I'm avoiding sugar cube relays because I only have minimal space in the case/box for this project, which is also why I need the component which wastes the least power since I couldn't fit a heat sink.

I have programmed the MCUs eeprom to turn the circuit on and off alternatively each time the setup is powered on and off so the latching feature of the thyristor/SCR is not a problem here. I also have opto-isolators to protect the MCU from high voltage.

So which one of those components is ideal for my project? Also if there are any other components which will do the job better please let me know.

Thanks in advance.

Best Answer

Use the MOSFET. Its use case is switching a DC load. If the LED strip has a lot of inductance, put a flyback diode across it.

If you drive the gate with 5 V relative to source, then the RDS(on) is specced as 0.077 ohms from the linked data sheet. The power dissipated will thus be 0.27 * 0.27 * 0.077 = 0.006 W. No need for a heatsink.