| 摘要 |
PURPOSE:To prevent a power supply from short-circuiting and the concerned DC motor from its misoperation by providing an abnormality detecting circuit for discriminating combination of control signals not normal while an output inhibiting circuit for controlling an output of the control signal on four control signal wires of an H bridge drive circuits. CONSTITUTION:Since AND gates 11, 12 of an abnormality detecting circuit 10 are not opened when an H bridge driving circuit 7 is normal, an output signal is generated from a NOR gate 13. Thus, AND gate 21 to 24 of an output inhibiting circuit 20 are opened, and a DC motor 5 is normally or reversely rotated by supplying control signals A, B or control signals C, D, left as they are, to switching elements 1, 2 or switching elements 3, 4. Since no output is generated by the NOR gate 13 by opening the AND gate 11 and/or 12 in the case of outputting a control signal such as short-circuiting a power supply 6, it is prevented from short-circuiting by cutting off supply of the control signals A, C and/or the control signals B, D to the switching elements 1 to 4. |
