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ADS8528: Device Performance when HVDD = 5V and HVSS=-5V

The datasheet shows +/-5V as a minimum operating voltage for HVDD/HVSS.

What are the impacts running at this minimum level?

I ask since when I review the data sheet, I see the input range is given as +/-2 x Vref, so if Vref = 2.5V, the input range is +/-5V.  But, the electrical specification table/device performance is for the condition of HVDD = 15V, HVSS = -15V.   I do not see information in data sheet about impact on device performance for the condition when HVDD = 5V and HVSS = -5V.

I understand it may not be able to run to the rails… but what if we guarantee that the channel input voltage will be less than 4.5V max, then what will be performance?

Carl

• Hi Carl,

Thanks for your post. Let me check with the systems team to confirm how this spec was meant to be interpreted.

What is the intended AVDD supply in this application? It is also tied to 5 V?

Best regards,

Ryan Andrews

Are you working on a bio-potential application? Check out these helpful resources: ADS129x FAQ | ECG Online Training

• In reply to Ryan Andrews:

yes,

AVDD= 5V

Carl

• In reply to Carl Wolfe:

Hi Carl,

Your customer should expect no degradation in performance while operating with HVDD/HVSS = +/- 5 V and 2xVREF input range = +/- 5 V.

The reliability of the internal reference voltage is dependent on AVDD. Figure 26. shows that VREF should remain constant across the entire AVDD range of 4.5 V to 5.5 V. Remember that the internal reference is only 2.5 V or 3 V, so AVDD is restricted to at least 4.5 V to ensure linear operation of the reference.

The analog input voltages are limited by the HVDD and HVSS supplies. Therefore, you can achieve the FSR of +/- 5V with a 10-V bipolar HVDD supply of +/- 5 V without performance limitations.

Best regards,

Ryan Andrews

Are you working on a bio-potential application? Check out these helpful resources: ADS129x FAQ | ECG Online Training

• In reply to Ryan Andrews:

Ryan,

Thanks for the information.  Good to see that performance is maintained.

Regards,

Carl

Carl