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choice of ADC

Intellectual 405 points

Replies: 14

Views: 8481

I'm using a apd5100 pressure sensor to monitor arterial line blood pressure. Since its an integrated sensor, i figured i could directly connect it to a 16 bit ADC.However I ain't sure of the choice of ADC for this application...as 1. the sampling rate 2. architecture-SAR/delta sigma 3. Input configuration range

Kindly help me out.

  • Hello,

    Unfortunately, we do not have details on this device. Do you have the datasheet, company/product page link, or any other details on this sensor? If so, then we will gladly look into some suggestions for an ADC.

    Regards,

    Michael Wheeler

    Regards,

    Michael W

  • In reply to Michael W:

    i apologise for the error...its an ADP5100 pressure sensor from panasonic...i decided to go for this one coz I couldnt fing any analog/digital output pressure sensors with a range of -700 to +700mmHg....if you have other suggestions, pls let know....Also, kindly answer my query with regards to the ADC.

     

  • In reply to amj:

    Hi amj,

    Looks like the ADP5x00 will get you +/-100kPA.  That should give you about .45 to 4.5V output.  Depending on your sample rate and resolution requirements, there are plenty of data converters from Texas Instruments to choose from. 

    A one channel  low power option might be to take the OPA365 configured as a simple voltage follower between the sensor and an ADS8326.  The output of the amp goes to the (+) ADC input, the (-) adc input goes to ground and you have a simple low power single supply option with 16-bits of resolution.  There are other options in the ADS8326 family that might be more appropriate based on what your end goals are - the ADS8326 datasheet lists six or seven ADC options on the first page if memory serves me.

    Let us know how you make out, this sounds like a fun project!

     

    Regards,

    Tom

  • In reply to Tom Hendrick:

    Thanks a tonne :)

    the datasheet of the ADS8326 states that Fclock=24*Fsample...why so? isnt clock frequency=no. of bits*sampling freq ? How many equivalent DCLOCKS would that be considering my Fsample=250kHz

  • In reply to Tom Hendrick:

    ultimately my ADC output should go to a Spartan 3AN FPGA...

  • In reply to amj:

    amj,

    The maximum SCLK speed the ADS8326 device can tolerate is 6MHz.  For 250KSPS, you would normally have the /CS tied low for 22 DCLKs to  transfer data and high for two additional DCLK cycles between conversions - see the top of page 8 for details.

     

    Regards,

    Tom

  • In reply to Tom Hendrick:

    Thankx Tom!

    any way i can obtain the spice model of those ICs..

  • In reply to amj:

    Hi Amj,

    The product folder for OPA365 contains the SPICE model for it, which you can find via the following link:

    http://focus.ti.com/docs/prod/folders/print/opa365.html#toolssoftware

    As for the ADS8326, there are no available SPICE models for it. However, there are 2 EVMs available, if you'd like to use those with your pressure sensor. For the EVM alone, that you could wire into your FPGA, we have the ADS8326EVM. If you would like a "ready to go" setup, that includes a controller and software, we have the ADS8326EVM-PDK.

    Regards,

    Michael

    Regards,

    Michael W

  • In reply to Tom Hendrick:

     Before trying this circuit with the sensor, i want to build the circuit by simulating the output signal characteristics of ADP5100 sensor...how do i do so and give it to OPA365?

  • In reply to amj:

    Hello Amj,

    You may try simulating the input using TINA-TI.

    Regards,

    Michael

    Regards,

    Michael W

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