[B-U585I-IOT02A Discovery kit] What is the maximum voltage to apply to VIN ?

[Chamo]

Hello,

I'm currently using and working on B-U585I-IOT02A Discovery kit. Today, I supply the board with STLINK source via CN8 connector. But I want to be able to supply it with 12V voltage. So I will now supply the board via VIN pins and connect jumper JP4 between pins 3 and 4.

On the user manual of the demoboard, it is written that VIN can be supplied with voltage up to 12V but when I take a look at the board schematic, it is written on page 8 "WARNING voltage applied to VIN < 11.5V". On the datasheet of the regulator that convert VIN to 5V_VIN, I do not see any mention of such a warning.

So I'm asking here what is the reason of this warning, and is it possible to supply safely the board with a VIN voltage of 12V ?

Thank you very much for your answer,

[Peter BENSCH · Accepted solution]

The voltage regulator at VIN is an LD1117S50, which can withstand an absolute maximum of 15V at the input, which definitely must not be exceeded. It would make sense to have a certain safety margin, e.g. 12...13V.

But there is a bigger problem with the capacitor C117 (10µF, GRM188R61A106KE69D), which is also connected to VIN and is only designed for 10V continuous operation. It is tested with 25V for 5 seconds, but this does not guarantee long-term function.

My recommendation: if you want to feed in 12V and can guarantee that you stay 100% below 14V, you can replace C117 with a more voltage-resistant type and then work with it.

Does it answer your question?

Regards

/Peter

[Chamo]

Thank you Peter for your response, it does answer my question. I have replaced capacitor C117 with a new one that can support 12V and it seems it's working with 12V power supply.

Have a great day,