LIS2DH12 is returning NACK when its address is applied on I2C communication

[kghin.1]

Hello,

We are using LIS2DH12 in one of our product. it is working fine.

However during pilot production we found that out of 100 units, 1 unit is not allowing any I2C operation.

When we probed on DSO, we found that it is not returning ACK for I2C address provided on I2C bus.

We checked assembly and it is good (same as another 99 in lot). Device is also looks good visibly (no damage).

Please if you can point what can be possible issue for this error.

Regards,

khodidas

[Eleon BORLINI]

Hi khodidas @kghin.1​ ,

Is the LIS2DH12 soldered on your custom board, right? Which are the Vdd / VddIO operating voltages and the pullup resistors' values? And does the LIS2DH12 share the I2C lines with other devices?

To be sure it is an issue related to the chip and not to some parasitic on the lines, did you try to de-solder the failing chip and solder again another chip on the same pcb?

-Eleon

[kghin.1]

Hello Eleon,

Thanks for your quick response.

Q: Is the LIS2DH12 soldered on your custom board, right?

A: Yes, LIS2DH12 is soldered on custom board.

Q: Which are the Vdd / VddIO operating voltages and the pullup resistors' values? 

A: Vdd and VddIO are supplied from 3V battery. 12K pull resistor.

Q: does the LIS2DH12 share the I2C lines with other devices?

A: no, LIS2DH12  doesn't share the I2C lines with other devices.

I will try de-solder the failing chip and solder again the new chip option.

But lets say new chip works, then the conclusion is failing chip had issue.

Our concern is , what that bad part or some other reason and how can we identify before assembly about bad part ?

Regards,

khodidas

[Eleon BORLINI]

Hi khodidas @kghin.1​ ,

it's indeed very strange to have a similar (huge) ppm number (1 on 100 failing)... the I2C/SPI communication lines devices (LIS2DH12 and in general all ST MEMS sensors) are tested at production line level.

How many failure did you find in total? Or is it the only chip failing? If you cannot test the parts without soldering them on your board, you could also try to solder again the same part on another fresh board and check if the device is failing. If you can, you could also test the current consumption of the failing part, to check if the issues is only on the digital lines or affects the whole chip.

-Eleon