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Protection features in PCB power supply

gyuunyuu1989 , 05-14-2023, 07:37 PM
This question is about protection features that should be present on PCB.It is not about power integrity.

These features should be present on the power delivery system, either using discrete components or ICs that contain these features:
1. Overvoltage protection: Protect the circuit components in the primary power input into the design is above a threshold.
2. Reverse polarity protection: Protect the circuit if the primary power input polarity is reversed.
3. Overcurrent protection: Shutdown power to the all loads in the circuit if the current exceeds a certain level.
4. Thermal protection: Shutdown voltage regulators if the voltage regulator itself goes above certain temperature threshold.
5. Short circuit protection: This is tied to 3, if there is short circuit, the power supply to all loads must be siezed.
6. Undervoltage protection: This is specific to circuit components, if supply voltage falls below certain threshold the component IC must be put into reset state, this reset signal is removed only when the power rail has become stable again.

These should be present on PCB signal I/O pins:
7. ESD protection: The IC pins that connect to external connectors must have ESD protection. I do not think that the voltage regulator pins need ESD protection but I could be wrong.
8. Overvoltage protection: There must be clamp diodes on the signal I/O lines so that signals going into ICs are clamped to protect the IC.

Are there any other features that must be designed into the PCB circuit that have no function other than protecting the system from damage besides what I mentioned in the list?
qdrives , 05-15-2023, 02:56 PM
About the only thing that "must" be is to prevent fire, burns and shock. In other words, those that can harm humans and/or life stock.
What you (and your customer) want, is more, but not mandated by law.

You additionally want to filter noise.
What is the power input? Does it require EFT or surge protection too?
gyuunyuu1989 , 05-15-2023, 03:35 PM
The circuit is small that contains FPGA.

What is EFT?
qdrives , 05-16-2023, 02:14 PM
EFT stands for Electrical Fast Transient. https://en.wikipedia.org/wiki/IEC_61000-4-4

Ok, so no mains (power) input?
What about the length of the cables attached to it? Or are you only interested in the power (supply) element?
gyuunyuu1989 , 05-18-2023, 03:26 PM
OK, lets look at the first one. The reverse polarity protection for a positive supply (high side and ground) can done using a diode or a FET trasistor. Is this correct?
robertferanec , 05-20-2023, 12:55 AM
This may also help:
IEC/EN61000 Standards for Power Supplies​

In some devices there are requirements for power supply still work even during short power input interruption.
qdrives , 05-20-2023, 09:13 AM
@robertferanec Great overview of the 61000 standards and limits. However, most of these standards are for mains powered devices only.
From the few answers I get, I assume it is not mains (no answer on that though).
qdrives , 05-20-2023, 09:17 AM
@gyuunyuu1989 Yes, reverse polarity protection is done by using a diode or FET (with intrinsic diode).
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