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Industrial PLC Analog Input +/-10 to 0-2.5V for ADC (Bipolar to Unipolar)

Rajkumar Ramadoss
Prodigy 130 points
Other Parts Discussed in Thread: PGA281, ADS8681, ADS8688

Hi All

I am designing industrial standard Analog Input module with a wide range of inputs as +/-10V, +/-5V, 0-10V, 0-5V. My ADC chip input range is 0-2.5V.

Could you please share if there is any Op-Amp reference design which converts +/-10V, +/-5V, 0-10V, 0-5V ranges to 0-2.5V for ADC inputs?

Your help is highly appreciated.

Regards

Rajkumar R

  • 0
    TI__Mastermind 23050 points

    Hi Rajkumar,

    If you are looking for a single chip that can accept all of these input ranges and be programmed as necessary, you may consider a solution with the PGA281. You just need to apply an offset voltage at the input (generated by a DAC or such) and set the attenuation accordingly. The output of the PGA281 is differential though so if you are driving a single ended ADC you will likely want a difference amplifier between the PGA and the ADC.

    PGA281 Bipolar in Unipolar Out.TSC

    Alternatively if you just need a circuit that can be adjusted to accomodate one of the ranges above, you could use this TI Precision Design as a starting point: 

  • 0
    TI__Genius 9165 points

    Hello Rajkumar,

    You can also consider ADS8688/ADS8681 series of ADC's. These ADC's have integrated programmable Analog Front end which can be programmed to capture the signals in various input ranges you require.

    The device operate with single 5V supply & you do not need amplifiers to drive this ADC.

    An integrated ALARM feature helps perform digital code comparison & generate an Interrupt if programmed.

    Let me know if you have any questions regarding this device operation.

    Thanks & Regards,

    Shridhar.