Tests to verify complete functionality of a PCB

Question

What tests can be carried out on a power supply PCB to verify its complete functionality?

For example:-

I have designed a custom board using the JCM3012S3V. It takes 12V input and produces 3.3V.

What tests does this particular board need other than basic power on and verifying the output voltage with respect to input voltage?

The designed board may be working fine, I don't want this board to impact the working of other boards.

I am talking about tests like:

1. Measuring the noise generated from the board

What other tests does a board need to pass?

Answer 1

Depends on how deep down the rabbit hole you want to go.

I'll list some tests that are done on pretty much every power supply I work on:

1. Load regulation:

   • Start at minimum load, or 5%-10% load and then step the load to 100% of your rated output and then back again. This can be done with an electronic load or some kind of mosfet + resistor circuit. Monitor output voltage on a scope. Take note of how far the voltage dips during 0->100, how far it surges during 100->0, and how long it takes to settle back to regulation. This is also a good way to estimate your phase margin if you don't have an analyzer.

2. Line regulation:

   • Measure your output voltage at nominal input, then at the lowest acceptable input and the highest acceptable input. Line regulation = (High-Low)/Nominal.

3. Ripple/Noise:

   • You already suggested this one, but it is a good thing to measure. Even if only to match with your maths.

4. Efficiency:

   • Power Out/Power In, easy peezy.

5. Short circuit/current limit:

   • What happens if you short circuit your supply? Does it have protections? Before doing a short, I'd lower your load resistance past 100% load and see how the supply reacts. Only do this if you put protections in place, I don't want to be responsible for hurting your supply.

For DC/DC converters, you can also test PSRR by injecting noise on top of your input voltage and seeing how much it is attenuated on the output. Requires a spectrum analyzer or a good scope.

There is much more out there, but like Andy said, it really depends on what you built, and what you deem acceptable. If you aren't making this for a customer or what have you, then it is all up to you.

Answer 2

Before you design something, you list the requirements and the functionality needed. This of course means including the desired performance expectations across the environmental conditions it is intended for. Then you design it. Then, because you have all this stuff written down, you test it.

If you don't make at least a half-hearted attempt to do the above, results can be disappointing. However, there is some light at the end of the tunnel. The device you linked will almost certainly embody most of the un-written-down requirements that you need so, start there and construct a test specification from the data sheet of that device.

What other tests does a board need to pass?

That's up to you to decide but, basic ability to deliver a stable voltage to your load (worst case) is usually up there as a favourite with most folk.