• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 48 subscribers
  • Views 194 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1158 On-channel resistance

Timothy Starr
Expert 2445 points
Other Parts Discussed in Thread: ADS1158

Hello-

The ADS1158 data sheet lists 80 Ohms for On channel resistance of the integral mux, typical. Any idea what the min and the maximum are? We would be willing to take statistical data rather than gaurenteed limits. Thanks and Best Regards,

-Tim Starr on behalf of DW'at'ID

  • 0
    TI__Mastermind 43915 points

    Hi Tim,

    We do not characterize/test max and min limits for the ADS1158 mux on. We state that its typically around 80 ohms for when we use it in TINA models, etc. The input impedance is rated at 65k but is going to vary with temperature and process variation making it almost impossible to measure and model exactly what the mux resistance is.

    Are they interested in the mux resistance to get an idea of what kind of voltage drop their will be across? Is the customer testing the chip and seeing problems?

    Regards,

    Tony Calabria

  • 0 in reply to Tony Calabria
    Expert 1395 points

    Hello,

    Given what you stated above regarding the 80 ohms for simulation, my customer is trying to avoid having to buffer each input because of expense since the part breaks out the MUX Out and ADC input pins to allow a signal conditioning stage to be inserted in the signal path.  Can he get by without the buffer since the input is actually rated for 65K?

    Thanks, in advance.

    Scott

  • 0 in reply to Scott Kerstein
    TI__Mastermind 44680 points

    Hi Scott,

    The ADS1158 breaks out the MUXout pins and the ADCin pins so that only a single buffer can be used to buffer all channels.

    If the output impedance of their source is low enough, then they could short the MUXout pins to the ADCin pins. You can consider the source impedance and ADC input impedance as a voltage divider.

    Regards,
    Chris