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LDC1000 minimal wire setup

Bjornar
Prodigy 200 points

Hi

We need to configure our measuring system in an application where we have limited access to leads.

What is the minimal wiering setup we can use with SPI to the LDC1000?

We do have a central microprocessor to read the data. I understand it could be in either half or full duplex where chip select is in use.

Could anyone direct me to a guide which explains both cases or just do a short list of the necessary connections in each case? It would be much appreciated.

Regards, Bjørnar

  • 0
    TI__Genius 14270 points

    Hello Bjørnar,

    For the LDC1000, the necessary connections are:

    1) VDD (5V), although this can be supplied locally,

    2) GND

    3) VIO (set to the same voltage as the microcontroller's VIO)

    4) SPI (SCLK/CSB/SDI/SDO)

    The next are optional:

    5) We generally recommend L measurements, but if you are not making L measurements; or if you can place a crystal next to the LDC1000, then you do not need to bring a signal to TBCLK.

    6) INTB is optional, but may be needed for your system design.

    Regards,

    ChrisO

  • 0 in reply to Chris Oberhauser66
    Prodigy 10 points

    thanks for that, it helped me very :)

  • 0 in reply to Cerine Veges
    TI__Genius 14270 points

    Great! We're always here to help.

    Regards,

    ChrisO

  • 0 in reply to Chris Oberhauser66
    Prodigy 200 points

    Hi Chris

    Thanks for that detailed breakdown.

    To be a bit more specific, we want to overmold the LDC circuit for a in situ subsea application and need to limit the actual wires that we need for the overmolded chip and coil to our subsea pressure housing where the microcontroller is. The uC sits on a main board reading several LDC1000s, so then my question is;

    Can the VIO be locally connected so that the LDC is in constant transmit mode? Maby I have misunderstood the functionaluty of this pin, please correct me, but doesnt the actual data output on SDO?

    We plan to use the L measurement so then we dont need an external oscillator as I understand?

    Do we need the SDI if we won't need to select when the chip shall be in send mode?

    So what is the actual wires we need to power and read the LDC circuit (LDC1000, coil, resistors, capacitances) in a minimal setup?

    3 wires going into the circuit:

    1) VDD (5V), although this can be supplied locally,

    2) GND

    3) SDO

    * VIO is connected to the VDD, voltage lowered to 3V via resistor.

    Regards, Bjørnar Lingjerde

  • 0 in reply to Bjornar
    TI__Genius 14270 points

    Hi Bjørnar,

    Unfortunately, you need to maintain the 4 SPI wires to interface to the LDC1000; the LDC1000 will not continuously transmit conversion results. Perhaps you can place a microcontroller in the same overmolding and use that to transmit out a continuous conversion result.

    Regards,

    ChrisO