RAK3172 Controller dead unexpectedly

Hi, I am Hardware engineer one of my projects we are using RAK3172 LoraWAN Controller.
We are developing a code for it on development phase controller does not responds certain time later.
initially controller working and fully operational later on the development its dead unexpectedly.
so removed the module and soldered new one its working fine on two days then its dead again.
So, I doubted the hardware I cross checked completely hardware itself fine nothing unexpected there.
till now I lost 5 RAK3172 Controller.
Help me to find out the issue please

Welcome to the forum @selvakannan

Please check your schematic against our recommended minimal reference design ==> RAK3272S Breakout Board Datasheet | RAKwireless Documentation Center

Without more information it is impossible to help you.

What is your power supply?
What supply voltage?
Did you connect reset pin as shown in the reference design?
What other peripherals did you connect to the RAK3172?
Can you share your schematic?

You are pulling up the I2C lines of the RAK3172 to 5V. That is wrong. The IO’s of the RAK3172 are only up to 3.3V. This might kill your RAK3172’s

1 Like
  1. I am Using XL1509 3.3V Buck Convertor IC for Power supply.
  2. +3.3V is my Supply Voltage to Controller
  3. yes i connected reset pin as shown i added my schematic in attachments
  4. Transistors, Tactile switches, LED, RS3485, MAX3232CSE+, CH340C, and 3 opto couplers i connected within the controller.

Don’t pull 3.3V signals to 5V. You are killing the STM32WLE5 inside the RAK3172.

Thanks, i will change it and update you.

Also make sure that whatever you connect to the RAK3172 through your headers MUST have 3.3V level on the pins!
If you have external sensors or other peripherals that work on 5V you need to use level-shifters.