This is semiconductor called as TDA2003. This TDA 2003 datasheet has pin out connection layout, sample schematic wiring diagram thermal data, electrical characteristic, and more. This chip has a circuit which enables it to withstand a voltage pulse train, on pin 5, of the type. If the supply voltage peaks to more than 40V, then an LC filter must be inserted between the supply and pin 5, in order to assure that the pulses at pin 5 will be held within the . A suggested LC network is shown in fig. 19. With this network, a train of pulses with amplitude up to 120V and width of 2 ms can be applied at point A. This type of protection is ON when the supply voltage (pulsed or DC) exceeds 18V. For this reason the maximum operating supply voltage is 18V. Full datasheet of this car radio audio semiconductor here.