In audio power IC's for car stereo there is a continuous trend towards more output power under the restriction of the supply voltage of the car battery. Output currents of several amps per channel are required to drive 2x25 or even 4x25 Watt BTL in 4 /spl Omega/ loads. (BTL: Bridge Tied Load). The IC's must be protected against short circuits of the outputs to ground and the supply voltage. Another requirement is protection against loaddump pulses. Loaddump is a temporary peak in the supply voltage that occurs in the application when the car battery is disconnected while the engine running. The requirements on the robustness of these power IC's, especially the output stages with the power transistors, are very high. Therefore, process variations influencing the breakdown voltages can have a significant effect on the robustness of these IC's and their overstress susceptibility.
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