| 摘要 |
PURPOSE:To prevent oscillation when an inductive load is OFF, by connecting Zener diodes between the collector and emitter of a drive-stage transistor simultaneously with the diffusion of the base and emitter of a transistor constituting a Darlington circuit. CONSTITUTION:On one surface of collector 10, drive-stage transistor Tr1 and output-stage transistor Tr2 are both formed. Between regions of Tr1 and Tr2, Zener diodes 20, 21 and 22 are formed at the same time as the diffusion of the base and emitter of the transistor. Then, three Zener diodes are connected in series. An equivalent circuit is shown in the figure 3. Since Zener diodes are incorporated in a chip constituting the Darlington circuit, the cost can be reduced and oscillation at the time when an inductive load is OFF can be prevented. |
