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Failure diagnosing circuit and method

  • US 6,056,384 A
  • Filed: 10/08/1998
  • Issued: 05/02/2000
  • Est. Priority Date: 10/08/1997
  • Status: Expired due to Fees
First Claim
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1. A circuit for facilitating failure diagnosis of switching elements constituting a bridge circuit for driving a motor, the bridge circuit being formed by connecting a first and a second switching element in series and connecting a third and a fourth switching element in series, connecting one motor input terminal between the first and the second switching elements and connecting a second motor input terminal between the third and the fourth switching elements, the circuit comprising:

  • pull up and pull down terminals respectively connected to the input terminals of the motor via resistors;

    monitor terminals respectively connected to the input terminals of the motor;

    said pull up/down terminals selectively providing two states including a pull up state for providing voltage for facilitating failure diagnosis to the motor input terminals and a pull down state for providing ground potential to the motor input terminals;

    means for switching the two states of the pull up/down terminals; and

    means for opening and closing one of the switching elements at a time;

    whereby a change in potential of the monitor terminals in correspondence with each combination of switching the states and opening and closing of the switching elements indicates open and short-circuit failures or lack thereof and thereby facilitates failure diagnosis of the switching elements without energizing the motor.

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