I have a customer about internal termination.
The OSCinP and OSCinM pin descriptions in the Pin Table on datasheet page 4 say "High impedance self-biasing pin."
But register R5 has a IPBUF_TERM bit which controls an internal termination, "Enables internal 50-Ω terminations on both OSCin and OSCin* pins. This function is valid even if OSCin input is configured as single-ended input."
However, the specifications table appears to be lacking a specification of that termination. So while R5 says it is 50, the tolerance is unknown.
On the other hand, the LMX2572EVM eval board has 51Ω terminations on it. Given internal terminations, this is somewhat of a surprise, especially since there's a GUI which controls lots of things that very easily could have the terminations controllable. The pin table plus the EVM are in conflict with R5.
I'd definitely prefer to use the internal terminations, if possible.
Are the internal terminations on OSCinP+OSCinM real on LMX2572? If so, what is the impedance tolerance?
Why doesn't the EVM take advantage of them? Does TI recommend their use, or is there a reason that external terminations would be preferred?
