This post explains for the Audio Power IC.
The Part Number is TB2929HQ.
The function of this semiconductor is 45W X 4-ch BTL Audio Power IC.
Preview images :
The TB2929HQ is a four-channel BTL power amplifier for car audio applications.
This IC has a pure complementary P-ch and N-ch DMOS output stage, offering maximum output power (POUT MAX) of 45 W. It includes a standby switch, mute function and various
0. High output power
1. Standby switch (pin 4)
2. Mute function (pin 22)
3. Built-in AUX amplifier from single input to 2 channels output (pin 25)
4. Various protection features
Standby Switch (pin 4) :
The power supply can be turned on or off via pin 4 (Stby). The threshold voltage of pin 4 is
set at about 3 VBE (typ.). The power supply current is about 0.01 μA (typ.) in the standby state.