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ADS7054: Select Fully Differential Amplifier for ADC

Hiep PhamHuu
Prodigy 10 points
Part Number: ADS7054
Other Parts Discussed in Thread: THS4551, , LMH6551

I want to measure small signal so i need high input impedance of amplifier (1MOhm). In datasheet of ADS7054, TI recommend use THS4551 family, but it have small input impedance (100KOhm). So i want change amplifier, Can I use another choice ? Ex:LMH6551. And what is different between them ?

  • 0
    TI__Expert 5485 points
    Hi Hiep

    Welcome to TI E2E forum !

    Ideally if you drive ADS7054 using one of the applications circuit shown in the datasheet, the effective loading of the input signal source will be similar to that caused by THS4551. It is mainly because of the biasing resistors used around amplifier. I believe you are more concerned about input loading here. Please correct me if I am missing something.

    If you need true high impedance then I would recommend using individual buffer to drive ADS7054 AINP and AINM pins. You can use dual packaged op-amp and use each one in buffer configuration to drive the ADC input pins. Buffer will offer true high impedance to your input signal source.

    Thanks & Regards
    Abhijeet