ADS1293: ADCmax

Hi,

  Are you referring to the Programmable Digital Filters?

  Would you please clarify and provide more info about what you mean by used ADCmax as a direct function of R2 and R3 without referencing the tables mentioned?

  Do you want to bypass the digital filters?

  According to the ADS1293 datasheet, those Decimation filters/digital filters cannot be bypassed as they are part of the ADC architectures to help ensure/maintain the performance and thus ADCmax depends on the digital filters configurations.

For your e.g. question -

Take Table 8 as example and reference,

For PACE CHANNEL, if R1, R2 and R3 are set to 1, 4 and any, respectively, then, the Max ADC output code(i.e. ADCmax) can be seen/expected will be 0x8000 for PACE channel.

For ECG CHANNEL, if R1, R2 and R3 are set to 1, 4 and 4, respectively, then, the Max ADC output code(i.e. ADCmax) can be seen/expected will be 0x8000 for ECG channel.

Thanks.

HI,

I receive correctly the output of the Programmable Digital Filters, that is ADCout..

To calculate the differential input (e;g IN1-IN2) I need the ADCmax relative to my config.

We find this parameter in the tables mentioned.

My wish is to get ADCmax directly via a function of R2 and R3(if ECG) and NOT by loockup in these tables.

Is that possible ? 

Relative to ADCmax all the 4 tables are identicals. ADCmax is not a function of "fs" nor R1, is it possible to explain why ?

Thanks

Hi Georges, 

Forgive us for the delay, the USA is on holiday until Tuesday. We'll have a response for you then. 

Kind regards,
Nick Z

Hi,

Thank you for your reply.

I understand that you cannot explain the details of your products.

The transfer fct of a CIC filter being related to R*M, and R1*M being constant (4), I understand that ADCmax is not a function àf R1.

 But for the rest, that is : ADCmax(R2) and ADCmax(R2,R3), I regret that you cannot explain them to me.

Thanks.

Hi Georges,

May I ask why do you need those info?

TI has the reserved right to decide what info to be shared and disclosed.

Hi Yang,

I am an automation engineer _retired_.

My actual _personal_ project is to design a PLC (Programmable Lgic Ctrl) based on ARM Cortex M4F and a QK kernel (Miro Samek).

One of the many tasks embedded in my PLC is based on ADS1293.

Then you see I am a passionated developer ...

It will be a pleasure for me if you could explain a bit the internals behind the famous ADCmax.

Thanks a lot for your understanding.

Hello Georges, 

Chien, our resident lead for this device is out today. He'll get back to you Friday. 

I can look to get you a answer, but tracking down the right experts might take up to a week.

Kind regards,
Nick Z