AD7176-2

Hi ,

 

I have planned to use AD7176-2 ADC in our project to read thermocouple, thermistor, RTD , Voltage , Current and strain gauge sensors. I am finding it hard to fix what is the conversion time and settling time.

 

I will be using one channel with output datarate @ 10ksps and Sinc5+sinc1 filter settings. In "Table 18. AD7176-2 Output Data Rate (ODR)". It mentions that @ 10KSPS Settling time is 100uSec. But it doesnt mentions about the conversion rate.

Please let us know what is Settling time? Is it applicable for ever conversion as I will be using external mux to provide input to the ADC and what is the conversion time. I have 16 channels to be converted.

Also I would like to know whether to use an continues conversion mode or single conversion mode. As the device is a battery operated I want an optimal solutions.

Regards,

ChiranjeeviM

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  • 0
    •  Analog Employees 
    on Jun 12, 2013 4:34 PM

    Hi Chiranjeevi M,

    The settling time is the time required for the digital filter to fully settle any step at the input or any data from another channel in the case where multiple channels are used. The duration of the settling time varies on what degree of filter is used and what output data rate is selected. The settling time is required for the first conversion on a newly selected channel or when moving from standby mode to any other mode. Subsequent conversions would then follow the selected output data rate (ODR) (ODR = conversion rate).

    The Sinc5 + Sinc1 filter is targeted at fast switching multiplexed applications and achieves single cycle settling at output data rates of 10 kSPS and lower. This means that for output data rates of 10 KSPS and less the conversion time and settling time are equal which is also known as single cycle settling.

    When using continuous conversion mode, the part will perform a new conversion as soon as the previous conversion was completed even if it has not been read. If there is a need to convert continuously, then, this mode can be used. If not, single conversion mode would work better as the ADC returns so standby mode after each conversion and waits for a write to the mode register before starting another conversion. This would save significant power if only occasional measurements are to be done.

    Thanks and Best Regards,

    Chris

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  • 0
    •  Analog Employees 
    on Jun 12, 2013 4:34 PM

    Hi Chiranjeevi M,

    The settling time is the time required for the digital filter to fully settle any step at the input or any data from another channel in the case where multiple channels are used. The duration of the settling time varies on what degree of filter is used and what output data rate is selected. The settling time is required for the first conversion on a newly selected channel or when moving from standby mode to any other mode. Subsequent conversions would then follow the selected output data rate (ODR) (ODR = conversion rate).

    The Sinc5 + Sinc1 filter is targeted at fast switching multiplexed applications and achieves single cycle settling at output data rates of 10 kSPS and lower. This means that for output data rates of 10 KSPS and less the conversion time and settling time are equal which is also known as single cycle settling.

    When using continuous conversion mode, the part will perform a new conversion as soon as the previous conversion was completed even if it has not been read. If there is a need to convert continuously, then, this mode can be used. If not, single conversion mode would work better as the ADC returns so standby mode after each conversion and waits for a write to the mode register before starting another conversion. This would save significant power if only occasional measurements are to be done.

    Thanks and Best Regards,

    Chris

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