Nucleo 144 STM32H7 ESD protection

[John Smith_2]

Hello!

I have a question about ESD protection of Nucleo 144 STM32H7 development board. As I've noticed from the schematics the board uses ESDA7P60, ESDALC6V1, USBLC6-2SC6 and USBLC6-4SC6 for ethernet, buttons, SWD connectors and USB.

Isn't it easier and more convenient to use one part in all these cases, for example USBLC6-4SC6? It suits ethernet, it also can be used for USB (just left 2 other channels not connected).

And is there any reason why USBLC6 cannot be used for user buttons or for external PLS connectors (SPI, UART, GPIOs' signals etc)?

Thanks in advance.

[TDK · Accepted solution]

You can use whichever ESD protection you want, note that this STM32H7 chip itself has a fair amount. The USBLC6 chip can be used for any of these.

[John Smith_2]

Thank you for the answer!

So I can simply put USBLC6 practically everywhere, except specific interfaces like RS232, CAN etc?

[LCE]

With all these different protectors ST made you look at all of them! ;)

> So I can simply put USBLC6 practically everywhere, except specific interfaces like RS232, CAN etc?

Basically yes.
Always think of how probable it is that ESD reaches the following semiconductors in the used environment.
Do the connectors have exposed pins and / or industrial environment?
Then use some "bigger guns", RS232 and CAN are good examples for that.

I almost never rely on any in-built ESD protection, unless it's a dedicated interface chip practically boasting about its ESD performance. And even then I check the use cases and environment .

In general, try to protect the complete system / PCB close to the connectors with ESD devices connected to the (hopefully grounded metal) case if possible.
If an ESD pulse gets somehow into your system / PCB it might be too late. Maybe nothing will get damaged, but a reset or some strange behavior might be as bad - and could lead to failing CE / FCC EMI testing.

[John Smith_2]

Thanks a lot!