Electrical – Power Supply for LED Array

led-driverpower supply

The circuit I have attached is basically LED arrays with some transistor and N channel Field-Effect Transistor. It requires 17v, 400mA to work. I will only glow either white led or RGB. They won't glow at same time, due to less current.
The N channel Field-Effect Transistor (XORB48) has

  • IDS: 5.8A
  • VGS: ±12V
  • VDS: 30V
  • CISS: 623
  • VGS(th) = 1.05V

It has low gate charger and operation gate voltages as low as 2.5V.

Each white led is of 0.2W (2835) and RGB is of 1W (5050) each.

I will control and dim the LEDs using Arduino PWM, for that individual GPIOs are connected, mentioned in circuit.

I want to know what kind of supply is needed for this? Constant current? Constant voltage? Does it require High power factor? How about ST's Viper22a or power integration's LNK IC?

Schematic :-

enter image description here

Best Answer

I want to know what kind of supply is needed for this? Constant current?

Well, your MOSFET has a 5R6 source resistor that will self regulate the current at about 125 mA so clearly a constant current supply isn't needed but, if as you say you designed this then why are you asking?

You might alo add a resistor in series with the GPIO line so that the BJTs that form part of the current regulation don't overstress the GPIO line if they conduct down to ground when current limiting.

You might also want to check what the gate threshold voltage is for those MOSFETs to make sure they can be activated with the limited voltage drive from your GPIO lines.