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How do I interface to multiple AD719x ADCs over the same serial interface ?

How do I interface to multiple AD719x ADCs over the same serial interface ?

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  • Hi Mayer,

    Yes that is correct - there is a maximum time between the /RDY going low and reading the data before it is lost. The data must be read a small time before the next /RDY signal. This is because /RDY goes high to indicate that a new conversion is about to complete and the data register will be updated shortly. This time is determined by the output data rate.

    The best way to ensure that no data is lost when using multiple ADCs is to synchronise the ADCs using the SYNC pin. The /RDY signal for all ADCs will then go low at the same time and you can cycle between all ADCs reading the data. As long as you can read the data from all ADCs quickly enough and without violating the maximum SCLK frequency spec then you will not lose any data. This depends on what speed you wish to operate the ADC.

    It should be noted that the AD719x can quickly multiplex the input channels to the ADC and so it would be possible that instead of slowly sampling multiple channels using multiple ADCs you could use a single ADC and quickly multiplex the inputs. There are tradeoffs to this approach but it may be a suitable option depending on your application.

    Regards,

    Rob

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  • Hi Mayer,

    Yes that is correct - there is a maximum time between the /RDY going low and reading the data before it is lost. The data must be read a small time before the next /RDY signal. This is because /RDY goes high to indicate that a new conversion is about to complete and the data register will be updated shortly. This time is determined by the output data rate.

    The best way to ensure that no data is lost when using multiple ADCs is to synchronise the ADCs using the SYNC pin. The /RDY signal for all ADCs will then go low at the same time and you can cycle between all ADCs reading the data. As long as you can read the data from all ADCs quickly enough and without violating the maximum SCLK frequency spec then you will not lose any data. This depends on what speed you wish to operate the ADC.

    It should be noted that the AD719x can quickly multiplex the input channels to the ADC and so it would be possible that instead of slowly sampling multiple channels using multiple ADCs you could use a single ADC and quickly multiplex the inputs. There are tradeoffs to this approach but it may be a suitable option depending on your application.

    Regards,

    Rob

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