I read the following in the NXP TDF8530 leaflet:
this ultra-efficient device supports 6 V stop-start applications and delivers audiophile sound quality
What does that "6 V stop-start applications" mean?
What it actually says is "... is an ultra-efficient, quad-channel Class-D audio amplifier that supports the 6 V requirement for start-stop vehicles."
Vehicles that stop and restart their engines for short periods of time (e.g., at stoplights) can experience power bus sags. What this brochure is saying is that this chip will be well-behaved even if the power supply sags as low as 6V.
"Stop-start" is a term used in the automotive industry for "intelligent" engines which stop and start when they aren't/are being used (for short amounts of time, to save fuel).
So that chip you have found handles the electrical ramifications of stopping and starting the engine, what ever these may be..