Voltage comparator hysteresis control circuit
First Claim
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1. A voltage comparator circuit for generating output transistions when an unknown voltage passes through a threshold voltage, comprising:
- comparing means having a first input coupled to said unknown voltage and a second input coupled to said threshold voltage and having an output at which said transitions occur; and
hysteresis control means coupled to said second input and to said output for permitting a hysteresis voltage to be applied to said second input only when said unknown voltage exceeds said threshold voltage and said threshold voltage exceeds a predetermined value, said hysteresis voltage being eliminated when said threshold voltage does not exceed said predetermined value.
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Abstract
A voltage comparator includes a hysteresis control circuit which utilizes a level threshold device. The comparator has a first input coupled to an unknown voltage and a second input coupled to a threshold voltage. The hysteresis control circuit includes means for generating a hysteresis current which is caused to flow through a hysteresis resistor coupled to the second input when the threshold voltage exceeds the threshold of the level threshold device and the unknown voltage is greater than the voltage on the second input of the comparator.
19 Citations
17 Claims
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1. A voltage comparator circuit for generating output transistions when an unknown voltage passes through a threshold voltage, comprising:
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comparing means having a first input coupled to said unknown voltage and a second input coupled to said threshold voltage and having an output at which said transitions occur; and hysteresis control means coupled to said second input and to said output for permitting a hysteresis voltage to be applied to said second input only when said unknown voltage exceeds said threshold voltage and said threshold voltage exceeds a predetermined value, said hysteresis voltage being eliminated when said threshold voltage does not exceed said predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A hysteresis control circuit for use with a voltage comparator having a first input coupled to a first voltage, a second input coupled to a second voltage, and having an output, said second input also coupled to impedance means, said hysteresis control circuit comprising:
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current generating means; and first means coupled to said second input, said impedance means, said output and to said current generating means for causing current to flow through said impedance means when said first voltage exceeds said second voltage and said second voltage exceeds a predetermined voltage different from said first voltage, said current being prevented if said second voltage does not exceed said predetermined voltage. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A voltage comparator circuit for generating output transitions when a first voltage passes through a second voltage, comprising:
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comparing means having a first input coupled to said first voltage and a second input coupled to said second voltage and having an output at which said transitions occur; and hysteresis control means coupled to said second input and to said output for permitting a hysteresis voltage to be applied to said second input when said second voltage exceeds a predetermined value.
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Specification