• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 32 subscribers
  • Views 479 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LDC1614: Is it possible to have more than 1 LDC on a PCB board

Gasikar
Prodigy 160 points
Part Number: LDC1614

Hi and happy new year everyone, 

I would like to have 2 LDC on a single PCB board. I would like to ask if it is possible and if there were any precautions to take for avoid disturbances, ....

Currently, I have a PCB we designed with LDC1614 "powered" by the same crystal oscillator (40MHz). When I used only one of the two LDC1614 on-board, everything works very well. When I activated the two LDC1614 I have a lot of amplitudes errors (low or high). When I correct ALE, a AHE error occurs and conversely. I am not able to find the right value of IDRIVE. The two LDC1614 have the same behaviour.

I don't know how to correct this issue. Do you think these errors come from the desogn of the PCB ?

Thanks a lot

  • 0
    TI__Expert 6625 points
    Hi Gasikar,
    Are you trying to sense the same target with both the LDCs ? Can you provide more information about your design such as where are the LDCs with respect to the sensors and target.

    Best Regards,
    Bala Ravi
  • 0 in reply to Bala Ravi
    Prodigy 160 points

    Hi Ravi,

    I have a different coil on 1st channel of each LDC. Each coil has ~120µH of inductance and 1.2Ohm of resistor.  

    A coil is made from wire winding and there is more than 40cm between each coil.

    When I use only one of the two LDC with this coil, everything works well. When I activate the 2 LDC in same time I have a lot of amplitude error and I could not  find the right value of IDRIVE. 

    I hope my answer may help you to understand the situation if not do not hesitate to ask more precision.

    In picture below, I circled the LDC in red and the XTAL in green. There is 5 cm between 2 LDC.

    Thanks a lot

  • 0 in reply to Gasikar
    Prodigy 80 points

    Hi Gasikar,

    It sounds like the two coils are coupling to each other -the two coils could be transferring energy by magnetic coupling to each other. Try to change the sensor frequency by >20% on one of the sensors to see if that fixes your problem.

    Edit: this is usually not a problem on a single LDC161x, because inactive channels of a single device are shorted. 


    Cober

  • 0 in reply to Chris Oberhauser
    Prodigy 160 points

    Hi Chris, 

    Thanks for your suggestion. I'll try it and I'll let you know.

  • 0 in reply to Gasikar
    Prodigy 160 points
    I added capacitor to change frequency on my 1st LDC. Currently, 1st LDC is on 590KHz and 2nd one is on 364 KHz. I still have the same behavior. There is always a lot of ampliture error.
  • 0 in reply to Gasikar
    Prodigy 80 points

    Well then, it's time for you to break out the scope and look at what you have on the sensor.