I made custom board using stm32f207 MCU and In few of board I have faced issue that board stops working after some time and, In STM Utility it shows RDP readout protection level FF and it doesn't execute the code and unable to reprogram.

[TVARS.1]

Read out protection issue ,I am unable to reprogram the board and the previous code is not executing as well. I have faced this issue in multiple boards .I am unable to debug this issue since long and the last option is to replace mcu with new one. Any support appreciated. Please check below attachment for ref

Thanks in advance.

[TDK]

Do other option bytes read out correctly/as expected? Does the chip draw the expected amount of current?

Chips dying after a bit is not typical and suggests there are hardware issues, perhaps an overvoltage condition.

[TVARS.1]

No, I cant read anything the mcu is in protection mode and I am unable to read or write anything even code inside not working.

[Tesla DeLorean]

Certainly sounds like a chip/board level failure.

Does any of your code write to FLASH? Use the EEPROM Emulation?

Here you'd need to be very concerned about the power supply, and also reseting properly. If you have multiple supply rails, or a supply that rises slowly you probably need some more effective POR circuit to hold the device in reset until the system is viable.

[TVARS.1]

Hello Tesla,

Thankyou for reply. Yes we are using internal flash for some flag storage.