Power-on reset for transponder
First Claim
1. An RF transponder comprising a plurality of circuits, a power supply for providing power, including an input voltage, to the plurality of circuits, and a one of the plurality of circuits comprising a Power-On Reset circuit for generating a reset signal for maintaining other ones of the plurality of circuits in an inoperative reset mode unless the power supply has sufficient power to ensure proper operation of the other ones of the circuits, the RF transponder characterized in that:
- at least one of the other ones of the plurality of circuits comprises control logic which, upon release of the reset signal, starts transmission of a data stream at a first bit of the data stream, in order to ensure a first-pass transmission of a complete data stream;
characterized by;
an input for an external reset signal; and
at least one logic element, for combining the external reset signal with the Power-On Reset-generated reset signal and forming a combined reset signal, wherein the combined reset signal is set in response to either the external reset signal or the Power-On Reset-generated reset signal being set, and the combined reset signal is cleared when the external reset signal and the Power-On Reset-generated reset signal are both clear;
characterized by;
a gate connected between ground and the input for the external reset signal, wherein the gate is controlled by a one of the power supply voltages so that the external reset signal is cleared when the power supply voltage is at a level suitable for logic control.
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Accused Products
Abstract
A power-on reset for a transponder (102, 200, 400) capable of measuring one or more parameters (e.g., temperature, pressure) in an object (e.g., a tire, 104) and transmitting a data stream (FIGS. 3C, 4B) to an external reader/interrogator (106). The transponder typically operates in a passive mode, deriving its power (Vxx, Vcc, Vdd) from an RF interrogation signal received by an antenna system (210, 410), but can also operate in a battery-powered active mode. The transponder includes memory (238, 438) for storing measurements, calibration data, programmable trim settings (436b), transponder ID and the like. A power-on reset circuit (600) prevents operation of the transponder until it is stable, and starts transmission of the data stream at a first bit of the data stream, in order to ensure a first-pass transmission of a complete data stream. It also prevents modulation of the antenna system for data stream transmission if the power levels are too low for stable transponder operation during modulation.
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Citations
19 Claims
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1. An RF transponder comprising a plurality of circuits, a power supply for providing power, including an input voltage, to the plurality of circuits, and a one of the plurality of circuits comprising a Power-On Reset circuit for generating a reset signal for maintaining other ones of the plurality of circuits in an inoperative reset mode unless the power supply has sufficient power to ensure proper operation of the other ones of the circuits, the RF transponder characterized in that:
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at least one of the other ones of the plurality of circuits comprises control logic which, upon release of the reset signal, starts transmission of a data stream at a first bit of the data stream, in order to ensure a first-pass transmission of a complete data stream; characterized by; an input for an external reset signal; and at least one logic element, for combining the external reset signal with the Power-On Reset-generated reset signal and forming a combined reset signal, wherein the combined reset signal is set in response to either the external reset signal or the Power-On Reset-generated reset signal being set, and the combined reset signal is cleared when the external reset signal and the Power-On Reset-generated reset signal are both clear; characterized by; a gate connected between ground and the input for the external reset signal, wherein the gate is controlled by a one of the power supply voltages so that the external reset signal is cleared when the power supply voltage is at a level suitable for logic control. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An RF transponder comprising a plurality of circuits a power supply for providing power, including an input voltage, to the plurality of circuits, and a one of the plurality of circuits comprising a Power-On Reset circuit for generating a reset signal for maintaining other ones of the plurality of circuit in an inoperative reset mode unless the power has sufficient power to ensure proper operation of the other ones of the circuits, the RF transponder characterized in that:
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at least one of the other ones of the plurality of circuits comprises control logic which, upon release of the reset signal, starts transmission of a data stream at a first bit of the data stream, in order to ensure a first-pass transmission of a complete data stream; characterized by; a flip-flop circuit for setting and clearing a state of the reset signal; and a voltage divider connected to a first comparator, for providing an input signal to a voltage limit circuit;
wherein the voltage limit circuit controls the flip-flop circuit so that the flip-flop circuit sets the reset signal in response to the input voltage by less than or equal to a minimum sustaining voltage, and clears the reset signal in response to the input voltage being greater than the minimum sustaining voltage;characterized by; an init delay circuit connected to an input of a second comparator which shares control of the flip-flop circuit with the voltage limit circuit, so that the flip-flop circuit holds the reset signal in an ON-state after the beginning of power-up for a longer one of a first period of time which is a delay time and a second period of time which is a time expended while the input voltage increases to greater than a minimum voltage. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. Method of controlling operation of an RF transponder during power-up and power-down, wherein the RF transponder comprises a plurality of circuits, a power supply for providing power, including an input voltage, to the plurality of circuits, and a Power-On Reset circuit for generating a reset signal for maintaining selected ones of the plurality of circuits in an inoperative reset mode unless the power supply has sufficient power to ensure proper operation of the plurality of circuits, the method characterized by:
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upon release of the reset signal, starting data transmission a first bit of a data stream to be transmitted, in order to ensure a first-pass transmission of a complete data stream; characterized by; holding the reset signal in an ON-state after the beginning of power-up for a longer one of a first period of time which is a delay time and a second period of tine which is a time expended while the input voltage increases to greater than a minimum voltage. - View Dependent Claims (17, 18, 19)
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Specification