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ADS8422: Inquiry Regarding Recommended Operational Amplifier

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Prodigy 20 points
Part Number: ADS8422
Other Parts Discussed in Thread: THS4541

Tool/software:

I am writing to inquire about...
Based on your datasheet, we have implemented the recommended interface circuit with the following components:

  • Operational Amplifier: "THS4131IDGKR"
  • ADC: "ADS8422IBPFBT"

However, due to circuit constraints, the operational amplifier is powered with a ±5V supply. In this configuration, the input voltage to the ADC is limited by the output voltage swing of the operational amplifier, which does not meet the required ADC input range of ±4.095V or higher.

Could you kindly recommend a suitable rail-to-rail operational amplifier that meets the following criteria?

  • Compatible for use as a front-end amplifier for the ADS8422IBPFBT
  • Capable of achieving an output voltage range of ±4.095V or higher with a ±5V power supply

I appreciate your assistance and look forward to your recommendation.

  • 0
    TI__Expert 6411 points

    Hi Sasaki-san,

    Thanks for your question. What kind of application are you planning to use this ADC for? You may choose to pair the ADS8422 with the THS4541 fully-differential amplifier (FDA), which meets your requirements.

    ADS8422 is an older device so I will also suggest some newer ADC options here, both of which were released this year, in case you are interested. They both use serial interface instead of parallel though. What is your input signal bandwidth? 

    • If it is 400kHz or lower, you may choose to use ADS9212 (18-bit, 8MSPS, 2 channel, simultaneous sampling ADC with serial interface). This ADC has an integrated ADC driver and can be used without an input driver.
    • If it is higher, you may explore ADS9227 (16-bit, 5MSPS, 2 channel, simultaneous sampling ADC with serial interface) which has 45MHz input signal bandwidth. This ADC may also be paired with the THS4541 FDA.

    Best regards,

    Samiha