[EDIT: This seems to be a bug in the LME49600 model as shown in my reply below. Can anyone fix its model ?]
I like the LME49600 for its low distortion and simple use as a high current driver in various applications and easy thermal management due to DPAK package.
I want to use it in a new role now, where I havent used it before: as a common buffer to tie the midpoint of a 36V supply to ground regardless of load imbalances.
Please refer to the figure below. I have used the spice LIB from the TI page of the LME49600 and BUF634A respectively. On the left is a usual output buffer circuit that I have used already and which simulates with no problems. The circuit on the right is a minimal model of the common buffer. It cannot simulate or (if forced) it diverges to one rail or starts at a huge input/output difference of 250 Megavolt (which should be clamped by internal diodes). If I plug the BUF634A model into the same circuit, it simulates without issue keeping the COM at close to GND.
So are the BUF634A and LME49600 indeed functionally different ?? I always thought of them as roughly the same in a different package.
If they are indeed similar: Can you please point out how to "fix" the spice model of the LME49600 ?
I feel the BUF would be a little too shaky for the expected current loads due to bad heat dissipation.