Voltage reference buffer (VREFBUF) in U545 packages

[OliM]

In the Datasheet it says:

"The VREF+ pin is double-bonded with VDDA on some packages. In these packages the
internal voltage reference buffer is not available."

Does this implicitly mean all packages which do not explicitly have a VREF+ pin can not use this peripheral or are there some inbetweens (which ones) which can use internal references, just not external ones?

I'm especially surprised that even the high pin count WLCSP variant does not have such a pinout, so the smallest package to even use that (imo very useful) feature would be a "huge" 7x7mm BGA Chip. 

[Amel NASRI · Accepted solution]

Hi @OliM ,

Currently, the VRAF+ is available only in LQFP100 and UFBGA100 packages.

What we say in datasheet as well as reference manual is "When the VREF+ is double-bonded with VDDA in a package, the internal voltage reference buffer is not available and must be kept disabled."

Referring to the "Table 347. VREF buffer modes" in the RM0456, only the following mode cannot be used:

This means that the External voltage reference mode can be used with packages where VREF+ isn't available.

-Amel

[OliM]

Thank you for the confirmation. Unfortunately for me this means either finding a different solution for measuring with constantly changing VDD or paying for a lot of unused stuff on an 585.