ADS131A04: Question about setting for VNCP, /DRDY timing, and input connection

Hello Victor,

Thanks for your post!

Yes, you are correct. When the internal negative charge pump is enabled, the VNCP pin (pin 11) will be forced to -1.95 V with respect to ground. The Electrical Characteristics table gives the typical (-2 V) and maximum (-1.65 V) voltages for the negative charge pump.

This pin should be bypassed with a capacitor between 220 pF and 470 pF.

Best Regards,

Thank you so much Ryan for your answer, I appreciate it.

Now I'm confused with the capacitor value. In accordance with datashett (Rev Jan 2018), page 81 states that capacitor should be 270 nF (same in Figure 109, also in table at page 6). Nevertheless, on page 80 (11.1) it is mentioned that such capacitor value should be from 220 pF to 470 pF.

Could you please confirm correct value?

I'm not able to get -1.95V on VNCP pin, what I have seen is around 1.7 V (positive), I'm using a 270 nF for that capacitor... I wonder if that is the reason.

Thank you!

Hi Victor,

Let me check with the design team. I also noticed that the EVM schematic uses 220 nF on VNCP, so there is definitely a mistake somewhere.

I should have an answer in a day or so.

Best Regards,