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Load driver and system with fault detection apparatus for providing a sequence of fault detection logic states

  • US 5,304,935 A
  • Filed: 12/17/1991
  • Issued: 04/19/1994
  • Est. Priority Date: 12/17/1991
  • Status: Expired due to Term
First Claim
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1. Load driver with fault detection apparatus, comprising:

  • semiconductor switch having a control electrode for receiving a switch control signal which determines on and off modes of operation of the switch, said switch having an output electrode for connection to an associated electrical load;

    W/R terminal for receiving a write/read control signal;

    C/stat terminal for receiving a command signal;

    circuit means coupled between said semiconductor switch and said W/R and C/stat terminals for providing said switch control signal to said semiconductor switch in accordance with said write/read signal and said command signal; and

    fault diagnostic circuit means coupled to said semiconductor switch and at least one of said W/R and C/stat terminals for monitoring operation of said semiconductor switch and its associated load and for providing, at said one terminal, a timed sequence of at least three predetermined logic states indicative of said monitored switch/load operation, each of said predetermined logic states indicative of, respectively, switch/load operation at sequential times (a) after said switch control signal attempts to turn said switch on and when said switch is supposed to be on, (b) at a first time after said switch control signal attempts to turn said semiconductor switch off, and (c) at a second time when said switch is supposed to be off, later than said first time, after said switch control signal attempts to turn said semiconductor switch off, a particular sequence of said three logic states indicating proper switch/load operation and each of three other sequences of said three logic states indicative of a different operational fault of said switch/load.

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