Programmable reset signal that is independent of supply voltage ramp rate
First Claim
1. A power-up reset (PUR) circuit for generating a reset signal, the PUR circuit comprising:
- a first node for receiving a reference voltage and a second node for receiving a supply voltage;
a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith;
a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith;
an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; and
a programmable delay circuit having an input for receiving a third control signal and an output for generating the reset signal, the delay circuit being configurable for selectively adjusting a delay between a change of logical state of the second control signal and a change of logical state of the reset signal in response to the third control signal;
wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal.
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Abstract
A PUR circuit for generating a reset signal includes a first node for receiving a reference voltage and a second node for receiving a supply voltage that is referenced with respect to the reference voltage. The circuit further includes a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node. The voltage level detector includes a first transistor having a first threshold voltage associated therewith. A resistance element is coupled between the second node and the third node, the resistance element having a first resistance value associated therewith. The circuit also includes an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal. The inverter includes a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage. The voltage level detector is configured such that the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage. The second voltage is less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal.
30 Citations
18 Claims
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1. A power-up reset (PUR) circuit for generating a reset signal, the PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; and a programmable delay circuit having an input for receiving a third control signal and an output for generating the reset signal, the delay circuit being configurable for selectively adjusting a delay between a change of logical state of the second control signal and a change of logical state of the reset signal in response to the third control signal; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal. - View Dependent Claims (2, 3, 4, 8, 9)
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5. A power-up reset (PUR) circuit for generating a reset signal, the PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to the first node, a drain terminal coupled to a fourth node, and a gate terminal coupled to the second node; and a second resistance element coupled between the third and fourth nodes, the second resistance element having a second resistance value associated therewith; wherein the second voltage is a function of the first and second resistance values.
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6. A power-up reset (PUR) circuit for generating a reset signal, the PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to a fourth node, a drain terminal coupled to a fifth node, and a gate terminal coupled to the second node; a second resistance element coupled between the third and fifth nodes, the second resistance element having a second resistance value associated therewith; and a third resistance element coupled between the first and fourth nodes, the third resistance element having a third resistance value associated therewith; wherein the first voltage is a function of the first threshold voltage and the third resistance value.
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7. A power-up reset (PUR) circuit for generating a reset signal, the PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to the first node, a drain terminal coupled to a fourth node, and a gate terminal coupled to the second node; a second resistance element coupled between the third and fourth nodes, the second resistance element having a second resistance value associated therewith; and a second transistor including a source terminal coupled to the first node, a drain terminal coupled to the fourth node, and a gate terminal for receiving a third control signal, the third control signal being operative to activate the second transistor when the supply voltage is ramping down and to disable the second transistor otherwise, the second transistor having a threshold voltage which is lower than the first transistor.
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10. An integrated circuit including at least one power-up reset (PUR) circuit for generating a reset signal, the at least one PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; and a programmable delay circuit having an input for receiving a third control signal and an output for generating the reset signal, the delay circuit being configurable for selectively adjusting a delay between a change of logical state of the second control signal and a change of logical state of the reset signal in response to the third control signal; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal. - View Dependent Claims (11, 12, 13, 17, 18)
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14. An integrated circuit including at least one power-up reset (PUR) circuit for generating a reset signal, the at least one PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to the first node, a drain terminal coupled to a fourth node, and a gate terminal coupled to the second node; and a second resistance element coupled between the third and fourth nodes, the second resistance element having a second resistance value associated therewith; wherein the second voltage is a function of the first and second resistance values.
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15. An integrated circuit including at least one power-up reset (PUR) circuit for generating a reset signal, the at least one PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to a fourth node, a drain terminal coupled to a fifth node, and a gate terminal coupled to the second node; a second resistance element coupled between the third and fifth nodes, the second resistance element having a second resistance value associated therewith; and a third resistance element coupled between the first and fourth nodes, the third resistance element having a third resistance value associated therewith; wherein the first voltage is a function of the first threshold voltage and the third resistance value.
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16. An integrated circuit including at least one power-up reset (PUR) circuit for generating a reset signal, the at least one PUR circuit comprising:
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a first node for receiving a reference voltage and a second node for receiving a supply voltage; a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node, the voltage level detector including at least a first transistor having a first threshold voltage associated therewith; a resistance element coupled between the second node and the third node, the resistance element having a first resistance value associated therewith; and an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal, the inverter including at least a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage; wherein the first control signal is substantially equal to the supply voltage when the supply voltage is less than a first voltage, and the first control signal is equal to a second voltage when the supply voltage is substantially equal to or greater than the first voltage, the second voltage being less than a lower switching point of the inverter, the first voltage being based at least in part on the first threshold voltage, the reset signal being a function of the second control signal; wherein the voltage level detector comprises; the first transistor including a source terminal coupled to the first node, a drain terminal coupled to a fourth node, and a gate terminal coupled to the second node; a second resistance element coupled between the third and fourth nodes, the second resistance element having a second resistance value associated therewith; and a second transistor including a source terminal coupled to the first node, a drain terminal coupled to the fourth node, and a gate terminal for receiving a third control signal, the third control signal being operative to activate the second transistor when the supply voltage is ramping down and to disable the second transistor otherwise, the second transistor having a threshold voltage which is lower than the first transistor.
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Specification