NXP Class D audio amplifiers have a unique feature called Thermal Fold Back. If the junction temperature exceeds the threshold level (Tj > 140° C), the gain of the amplifier is decreased gradually to a level where the combination of dissipation and the thermal resistance from junction to ambient results in a junction temperature around the threshold level. This means the device will not completely switch off, but remains operational at lower output power levels. Especially with music output signals, this feature enables high peak out power while still operating without any external heat sink.