I'd like to permanently put to rest all this speculation about TI inhibiting PFFB implementations with patent/licensing threats/intimidations/cost.
Having spent, in a "former life", many 100's of hours with TI intellectual property attorneys, including extensive cross-licensing agreements with literally 100's of technology companies, I can guarantee that TI is not soliciting license fees from TPA3255 customers. Never. In. A million years.
TI virtually never enforces patents against their customers. They enforce their IP against their peer group: semiconductor companies. These demographics occasionally overlap (a company like Samsung, for example, who have a semiconductor subsidiary) and then it gets a little more gray. But for the sort of companies using TPA3255 in products here on ASR, there would be zero legal obstacles (originating from TI) to implementing the PFFB app note.
My best guess at why we don't see more PFFB is:
- many of the products/designers probably don't believe their primary customer demographic would understand/value/demand the functionality
- despite it not being rocket science, the technique *does* add complexity to the design. Many here argue its a trivial effort, but they aren't the ones held accountable for a stable, mass-produced PCB design. Every marginal function/complexity adds to the effort.
- although the PFFB technique example is > 5 years old, the "demand" for it and retail implementations of it have only emerged relatively recently. But as examples like 3e have recently come to market (sort of . . . their online store is empty 8 of 10 days) I think we can expect many companies who want to capture "audiophile" customers for TPA3255 based products to add PFFB in the near future.
