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sivaji , 06-12-2025, 03:14 AM

I'm working on a project using the Raspberry Pi 3B+.
Normally, we power the Raspberry Pi through the USB power port. But in my setup, I can't use external USB power.

So instead, I'm using a 24V DC power source, which I step down to 5.2V DC using an XL4015 buck converter.
This 5.2V output goes through a power protection circuit, and then I supply the Raspberry Pi's 5V and GND through the GPIO header.

Everything is working fine so far.
But I'm worried about worst-case overvoltage situations — if a spike happens and the voltage goes above 5.2V, the Pi might get damaged.

To protect it, I added an overvoltage protection circuit. Here's the problem I'm facing:
When an overvoltage is detected, the protection circuit immediately cuts off power — the 5.2V drops to 0V instantly.

Because of this sudden loss of power, the Raspberry Pi can’t shut down properly, which may lead to data corruption or damage.

My Idea:

I want to build a system where:

When overvoltage is detected,

The circuit sends a signal to the Raspberry Pi,

Then the Pi will safely shut down before the power is cut off.


But I’m not sure how to implement this properly.

Can you suggest a reliable way to detect overvoltage and safely shut down the Raspberry Pi before power gets disconnected?

QDrives , 06-12-2025, 04:41 PM

Overvoltage on what? The 24V or the 5.2V?

If the 24V, then why not protect the 24V input?
- TVS diode
- Filter
- Bulk capacitance

QDrives , 06-12-2025, 04:42 PM

Have enough bulk capacitance to survive an under-voltage to do the required actions.

Robert Feranec , 06-13-2025, 05:10 AM

I think the problem is this: "When overvoltage is detected, The circuit sends a signal to the Raspberry Pi, Then the Pi will safely shut down before the power is cut off." but before you talk "if a spike happens and the voltage goes above 5.2V, the Pi might get damaged.".

These are two different situations. Spike can be solved as @QDrives explained, but the "long overvoltage" (or the overvoltage that goes through the peak filter) should be cut off immediately (or you would need to design your input regulator to be able to handle it).

sivaji , 06-21-2025, 04:17 PM

Thank you for your inputs @QDrives and @Robert Feranec

sivaji , 06-21-2025, 04:26 PM

Yes, the problem you described is correct. To handle voltage spikes, I plan to add a TVS diode and a bulk capacitor for transient voltage protection.

However, my concern is with prolonged over-voltage or under-voltage conditions, which could potentially damage the Raspberry Pi.

To address this, I explored various options and came across the TPS25944A protection IC.
I would like to know whether the TPS25944A is a reliable choice for this kind of protection.

Here is the datasheet for reference: https://www.ti.com/lit/ds/symlink/tps25944a.pdf

QDrives , 06-22-2025, 03:57 PM

What do you mean with "prolonged"...?
1) The TPS25944A is for up to 20V (max) while the XL4015 is for up to 36V.
2) A TVS diode has many voltages - standoff, breakdown and clamping. You cannot be 'prolonged' above the breakdown voltage.
3) With a TVS diode or any overvoltage protection system (like MOVs and GDT) you want the clamping voltage below the maximum input voltage of your regulator.
4) For prolonged overvoltage above breakdown and clamping, you need to add a (non-resettable) fuse. eFuses do not help as you need to be before the TVS device.
5) Capacitance does a lot for transient suppression. Simplistically you could see it as Vin * Cin = Vout * Cout.
6) For under-voltage (power disconnect) it is simply a bulk capacitance on the high voltage input (24V in this case) to give a signal to the PI when it drops below say 12V and you have enough capacitance to do your thing before it drops to 6V.
7) If you mean applying 48V to your system as a "prolonged overvoltage" you need to design your system for 48V, even if that means a fuse blown or a hot-swap circuit not conducting.

sivaji , 06-23-2025, 06:03 PM

Thanks for all valid point. I will consider them try to incorporate in my circuit