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Original question:

ADS54J40: ADS54J40 : ADC analog input schematic

ADS54J40: ADS54j40 input protection

Li Yang
Prodigy 100 points
Part Number: ADS54J40

   In ADS54j40 datasheet analog input section, it states that the each input pin must be between VCM + 0.475V and VCM - 0.475V.  Can you please let me know if the swing is over +/-0.475V,  will it damage the ADC chip??

In the datasheet, it only show the max value for INP. INM within -0.3V and 3V. This is reference to the ground not the differential pins.

In our application,  we have a remote sensor and and AC coupled to the ADC.  pic as below, can you please help review if that's sufficient protection?

thank you.

Li

 

  • 0
    TI__Guru* 91947 points

    Li,

    The max recommended swing would be +/-0.5V per pin. The analog pins would see a max of 3V in this case. Since the analog inputs are AC coupled, the ADC will bias the inputs to the CM value of 2V. The part will be safe but you may start to see some distortion. If your swing is +/-0.6, you will be at the absolute maximum for the analog inputs. Any higher and damage could occur.

    Regards,

    Jim