[SOLVED] Help ADXL001, output not changing

1 post / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

UPDATE: Forget it, I was doing the most stupid thing, was measuring it when fliping in the none-sensing axis.


And I'm stuck again.
I have a bunch of ADXL001 acelerometers which I've soldered to a board and work.

Now I've designed and build a new board, very similar with the previous working one, but on this new one, the acelerometer output doesn't change.

The chip has 8 pins.


On the first design, there's a 3.3 LDO constantly connected to the power supply, so the MEMs is always energized.
the VDD pins are connected to the 3.3V power line, the ST pin is connected to a header (which is left unconnected)
The Output is connected to a header which is then connected to a Low Pass Filter (Sallen-Key Topology).

On the new design, there's the SAME 3.3 LDO, but in this case is connected to a digital switch (MAX4645) so the LDO can be turned off.
The acelerometer: the VDD pins are connected to the 3.3V from the LDO output (same as before), the ST pin is left unconnected (which would be the same as before)
The ouput is connected directly to same filter as the previous design.

¿The problem?
The acelerometer in the previous board, changes ~30mV when flipping it around which is what the datasheet specifies (16mV/g @ 3,3V --> fliping the accelerometer means changing from -1g to +1g).
In the new board, no matter how much 'fliping' there is, the output voltage is constant, doesn't change.

I'll try to upload an image with both schematics once I simplify them.