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I am having a issue running LIS2DW12TR in 3V environment, the part is working fine at 1.8V once i plug the device to 3V supply it will start getting high current and some times burn.

Jpena.1
Associate

‎2020-07-02 05:50 AM

0693W000001s1jTQAQ.pngwe already cut trace the pin SDO connected to GND but still same issue, INT1&2 not connected physically by flipping MCU pin so it will not connect, the most ideal for our application is run the accel in 3V supply so we do not need a translator or any 1.8V LDO to save board cost.

i attached our schematic for your reference.

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Eleon BORLINI
ST Employee

‎2020-07-07 07:07 AM

Hi @Jpena.1​ , this is strange because the LIS2DW12 chip should have no problems if powered at 3V or 3.3V... The schematic appears OK too. You should check if there are some low-resistance paths from Vdd to GND, maybe not inside the MEMS device but in the STM8, removing selectively the MEMS first and then the STM8 devices...

About the I2C communication, the only thing I would check is the integrity of the I2C signal: I mean check with the oscilloscope if the 3V / 3.3V digital wave pattern signal is not for some reason shaped from parasitic capacitors on the SDA / SCL lines or maybe the pull-up resistors are too weak to guarantee the digital signal to reach the HiV level. Regards

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Jpena.1
Associate

‎2020-07-08 03:01 AM

Hello @Eleon BORLINI​  , we were able to fixed other issue.

Issue #1: On the burning of the Accelerometer chip at 3.3V supply

  • Its a solder issue on the board.

issue #2 : Good solder but the Accelerometer chip is not responding thru I2C communication and INT1&2 Accel pins are connected to MCU directly ( note: MCU pins connected to INT1&2 pins of Accelerometer are set to default state, input floating )

  • Because the MCU pins are pulling current from the INT1&2 of the Accelerometer chip that affects its power that is why its I2C communication lines are dead or disabled. The issue was solved by connecting a series resistor 4.7k ohm between Accelerometer chip INT1&2 to MCU pins. this will limit the current from Accel chip which is limited to 4mA only.

unsolved issue: Can we direct connect the Accelerometer pin 3 (SA0) to change the I2C ADDRESS? if no, do we need to connect a smaller pull down resistor smaller than the default internal pullup? what is the initial state of the Accelerometer communication line? is it SPI ? then shift to I2C if it detected that the Accel pin 2 is connected to VDD?

Regards,

Jing

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