A Very Low Noise μP, Interfaced, Multiple High Side Driver with Self Diagnostics for Car Radio Application

Modern car radio applications demand small, low cost power devices that can control large currents with the lowest power dissipation. These devices must be very low in EMI and easily adaptable to “distributed” radio system along the vehicle. This paper will discuss a new multiple high side driver realized in a mixed Bipolar-CMOS-DMOS 60V technology capable of delivering several Amps.

The mixed technology approach also allows the realization of a complete set of built-in Diagnosis circuitry monitoring the functionality of the different outputs, open, short, thermal status. Over 700 CMOS gate digital interface makes this available for distributed car radio applications on a serial Bidirectional Bus. To extend the total system functionality each of the three channels have an independent temperature sensor. This permits the radio to continue to operate even if an overload affects one of the auxiliary functions. Rdson versus die size of the high efficient N channel DMOS output devices was optimized by the use of a Computer aided Power DMOS layout generator and double level of Aluminum metalization. In order to meet the EMI car radio requirements, a low noise internal charge pump drives the N-channel DMOS outputs.