The main features of this powerful MULTIWATT®  package (a trademark of SGS-THOMSON Microelectronics), a  power amplifier IC chips designed specifically for car radio application, are the high current capability (3.5A) and the capability to drive a very low impedance (down to 1.6R). Here is the schematic diagram of the standard circuit as shown in its data sheet.

car amplifier circuit schematic

TDA2004 has low  noise, low distortion, and robust.  The robustness is supported by its operation safety protection features: very inductive loads, load dump voltage surge, overheating, output AC-ground short, fortuitous open ground. Other important things is space and cost saving : very low external components counts, and very simple mounting system with no need for electrical isolation between the package and the heat sink because the heat contact metal of the package is already connected to ground. [Circuit’s schematic diagram source: SGS-THOMSON Microelectronic Data Sheet]