Automotive current sensor

  • US 5,426,416 A
  • Filed: 10/19/1992
  • Issued: 06/20/1995
  • Est. Priority Date: 10/19/1992
  • Status: Expired due to Fees
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First Claim
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1. An essentially temperature invarient current sensor suitable for use in an automobile to measure a current delivered from a source of electrical energy to a load and configured upon occurrence of internal failure to indicate a maximum current level, said sensor comprising:

  • a shunt assembly connectable in line with said source and said load, said shunt assembly having at least one low-resistance shunt element constructed of a material having characteristically small resistance drift due to variations in ambient temperature;

    a difference mode amplifier having a first input electrically connected to a first terminal side of said shunt and a second input electrically connected to a second terminal side of said shunt element, said difference mode amplifier producing a difference signal representative of a voltage drop across said shunt element due to a flow of current;

    said difference mode amplifier further including means for producing upon disconnection of said first and second inputs from said shunt element a voltage difference sufficient to indicate said maximum current level;

    scaling circuitry electrically connected to receive said difference signal and operable to produce during normal operation of said difference mode amplifier a ratiometric current level signal; and

    said scaling circuitry further operable during failure of said difference mode amplifier to produce a signal indicating said maximum current level.

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