TPA3139D2 Inductor-free Class-D Audio Amplifiers Texas Instruments TPA3139D2 Inductor-free Class-D Audio Amplifiers have a fast turn-on time (15ms) and a MUTE function to quickly power up while avoiding pop. The built-in spread spectrum control scheme efficiently suppresses EMI and enables using ferrite beads instead of inductors for ≤2 x 10W applications.