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LDC1614EVM: Helmholtz Coil-LDC1614

Alexander Luis
Prodigy 180 points
Part Number: LDC1614EVM
Other Parts Discussed in Thread: LDC1614

Dear Forum,

I have been using three separate LDC1614EVM to drive each of my three axes Helmhotlz Coil, and request clarification on the following:

 

Reference Count 2.4.4 (Using Channel 0)

 

RCOUNT                              Conversion Time

0xFFFF                                   26.2 ms

0x0FFF                                   1.6 ms

0x00FF                                    0.1 ms

 

1. Are these fixed or can I make the conversion time faster or slower and what is the limit ?

 

2. I am using the Teensy 3.6 micro-controller and wish to drive each of the three LDC1614 to its maximum current (DRIVE_CURRENT_CH0 ) without damaging it, what should the setting be (0x0080 default) in the Current Drive Control Registers ? I’m trying to maximize the magnetic field inside each coil as to increase my signal.

 

Thank you for your support and please understand that I have been teaching myself how to collect data with micro-controllers.

 

Sincerely,

 

Alexander Luis

 

  • 0
    TI__Genius 14270 points
    Hello Alexander,

    1) The conversion time is a function of the reference frequency and the RCOUNT setting. You can set the RCOUNT to any value between 4 and 65535 - the conversion time will scale linearly with this setting.

    The other parameter is the reference frequency -you can input any frequency into the external CLKIN input that is 4x the maximum sensor frequency up to a maximum of 40MHz, or you can use the internal reference frequency. The higher the reference frequency, the shorter the conversion time. This is detailed in the datasheet - refer to equation 6.

    2) Set the drive current based on the sensor Rp. If you set the drive current too high, then the sensor signal will be clipped by the LDC's protection circuity, which will increase the conversion noise significantly. Driving excessively high levels for extended periods is not recommended.

    Regards,
    ChrisO