Power Supply Calculation

[Beswad]

Can anyone help me to calculate the correct DC power supply I will need to power 80 laser diodes rated at 5V @ 40mA, all connected parallel?

[Old_Geezer]

Multiple the current for each diode by the number of diodes to get the required current. Add a percentage as you don't want to run at max. You already know the voltage.

Power in Watts is Current in Amps * Potential Difference in Volts.

That said surely this circuit consists of more than just the diodes ?

[dekkypoo]

That would be 5v @ 3.2 A should you want them all running at maximum output

[mibn2cweus]

If you connect them in parallel you'll need a current regulator for each one.

[Beswad]

Thank you all. Will likely to use a power resistor to limit the current flow.

[mibn2cweus]

An advantage of wiring some in series is that you are then assured they are all (in each branch) carrying an equal current.

If you were to use a 24v supply, grouping the diodes into 20 parallel branches of four each in series with a 100 ohm (1/2 watt) resistor to help equalise the current in each branch, the total current supplied would then be 20 * 0.04 = 800ma.

As long as the supply is designed to provide the required current at the rated voltage, there should be no problem.