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Processor supervisory circuit and method having increased range of power-on reset signal stability

  • US 5,850,156 A
  • Filed: 02/07/1996
  • Issued: 12/15/1998
  • Est. Priority Date: 02/07/1996
  • Status: Expired due to Term
First Claim
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1. For use in a processor supervisory circuit, a power-on reset circuit, comprising:

  • an adaptive, nonlinear voltage divider having a voltage input and a voltage output, said divider dividing an unscaled, unregulated voltage received at said voltage input by a factor that varies as a function of said unscaled, unregulated voltage to produce a scaled, unregulated voltage at said voltage output; and

    a comparison circuit for comparing said scaled, unregulated voltage with a scaled, regulated voltage to produce a power-on reset (RESET) signal when said scaled, regulated voltage exceeds said scaled, unregulated voltage, said divider being adaptive and nonlinear to ensure that said comparison circuit continuously produces said RESET signal when said scaled, regulated voltage exceeds said scaled, unregulated voltage and thereby avoid premature activation of a processor couplable to said power-on reset circuit, said comparison circuit employing positive feedback to obtain transfer characteristics with hysteresis.

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