A monolithic power op amp

The standard junction-isolated power process has been modified by the addition of polycrystalline-film resistors to solve the topological problems encountered in making 90-W, 80-V, 10-A power transistors and connecting them together for a push-pull output. An all n-p-n output stage that holds crossover distortion to 0.01% while driving a 4- Omega load, even with the quiescent current below 20 mA, has been developed. It is stable with all reactive loads and does not have the spurious-oscillation problems observed with the familiar quasicomplementary amplifier. These innovations are described along with the design of a complete power op amp, the LM12. The prevention of failures from substrate currents which occur when the output is driven outside the supply by inductive loads is discussed.<
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