Tool/software:
Hi,
I'd like to design a PCB for TPA3251 based on TPA3251 EVM board and apply PFFB. However I have some questions about the PFFB application;
- In both SLAA788a and SLAA702 application notes, the opamp input stages reffered as differential input. But I want to apply SE input also. So If I simply connect the lower opamps (input B and D) input to the upper opamps (input A and C) output like TPA3251 EVM and apply PFFB, is it cause any problem?
- After PFFB application, to compansate the overall gain I'll incerase the first opamps (input A and C) FB resistors to 28K. So do I need to change the second opamps (input B and D) FB resistors to 28K also or they will stay as 10K?
- It seems in both application notes (SLAA778a and SLAA702) the opamps fed with symmetircal supply. And opamps + inputs are biased at GND point. However in TPA3251EVM we use single supply to feed opamps and naturally their + inputs are biased at 1/2Va. So if we consider I will apply PFFB this situation causes any problem?
- If we compare two application notes; in SLAA702, just a 18K resistor used as global feedback and as zobel network 2.7R + 1u used. But in SLAA778a two capacitors and a resistor to GND are added to the global feedback, also zobel network is revised to 1R + 220n. So which option is better?
Thank you in advance for your help.
