Apparatus and method for an active power-on reset current comparator circuit
First Claim
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1. An apparatus for producing a power-on reset signal, comprising:
- a current generator circuit that includes a first resistance circuit coupled between a first node and a second node, wherein the current generator circuit is arranged to produce a first current at startup; and
a comparator stage that is coupled to the current generator and includes a second resistance circuit coupled between the first node and a third node, wherein the comparator stage is arranged to compare a second current to a third current such that the power-on reset signal is actuated when the third current is greater than the second current, wherein at least one of the second current and the third current corresponds to the first current according to a specified ratio such that a point is selectable during startup at which the power-on reset signal is actuated.
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Abstract
An active power-on reset (POR) current comparator circuit creates a POR signal for resetting logic devices and masking reference startup signals during the initial power supply ramp of an integrated circuit. The comparator circuit provides a logic level signal (i.e., the POR signal) that will actuate when a bias current is above a predetermined level as compared to another current. The predetermined level for the bias current is set by a ratio established between two resistance levels within the active POR current comparator circuit.
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Citations
20 Claims
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1. An apparatus for producing a power-on reset signal, comprising:
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a current generator circuit that includes a first resistance circuit coupled between a first node and a second node, wherein the current generator circuit is arranged to produce a first current at startup; and
a comparator stage that is coupled to the current generator and includes a second resistance circuit coupled between the first node and a third node, wherein the comparator stage is arranged to compare a second current to a third current such that the power-on reset signal is actuated when the third current is greater than the second current, wherein at least one of the second current and the third current corresponds to the first current according to a specified ratio such that a point is selectable during startup at which the power-on reset signal is actuated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method, comprising:
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producing a first current at startup, wherein the first current flows across a first resistance circuit that is coupled between a first node and a second node;
producing a second current at startup, wherein the second current flows across a second resistance circuit that is coupled between the first node and a third node and the second current corresponds to the first current according to a specified ratio;
producing a third current at startup, wherein the third current corresponds to the first current;
comparing the third current to the second current; and
actuating a power-on reset signal in response to the comparison of the third current to the second current, wherein the point during startup at which the power-on reset signal actuates is dependent on the specified ratio between the first current and the second current. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. An apparatus, comprising:
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means for producing a first current at startup, wherein the first current flows across a first resistance circuit that is coupled between a first node and a second node;
means for producing a second current at startup, wherein the second current flows across a second resistance circuit that is coupled between the first node and a third node and the second current corresponds to the first current according to a specified ratio;
means for producing a third current at startup, wherein the third current corresponds to the first current;
means for comparing the third current to the second current; and
means for actuating a power-on reset signal in response to the comparison of the third current to the second current, wherein the point during startup at which the power-on reset signal actuates is dependent on the specified ratio between the first current and the second current. - View Dependent Claims (17, 18, 19, 20)
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Specification