Apparatus and method for reducing errors in a battery operated sensing circuit
First Claim
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1. An apparatus for reducing short circuits in a circuit, comprising:
- a first pull-up resistor having a predetermined resistance value;
a second pull-up resistor having a predetermined resistance value lower than the first resistor; and
means for selectively coupling the resistors with the circuit, wherein the means for selectively coupling periodically couples the first resistor to the circuit, and couples the second resistor to the circuit after a signal is sensed when the first resistor is coupled with the circuit.
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Abstract
An apparatus and method for reducing errors in a battery powered sensing circuit uses two pull-up resistors. The first resistor has a value selected to minimize battery drain and the second resistor has a value selected to reduce dendrite or other parasitic parallel resistance. The resistors are selectively connected to the circuit based on a predetermined sequence and/or time interval.
18 Citations
26 Claims
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1. An apparatus for reducing short circuits in a circuit, comprising:
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a first pull-up resistor having a predetermined resistance value; a second pull-up resistor having a predetermined resistance value lower than the first resistor; and means for selectively coupling the resistors with the circuit, wherein the means for selectively coupling periodically couples the first resistor to the circuit, and couples the second resistor to the circuit after a signal is sensed when the first resistor is coupled with the circuit. - View Dependent Claims (2, 3)
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4. An apparatus for reducing short circuits in a circuit comprising:
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a first pull-up resistor having a first resistance value; a second pull-up resistor having a second resistance value lower than the first resistance value; and means for selectively coupling the resistors with the circuit, wherein the circuit is battery-powered, and wherein the first resistance value is selected to minimize battery drain and the second resistance value is selected to reduce parallel parasitic resistance in the circuit.
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5. An apparatus for reducing short circuits in a circuit, comprising:
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a first pull-up resistor having a predetermined resistance value; a second pull-up resistor having a predetermined resistance value lower than the first resistor; and means for selectively coupling the resistors with the circuit, wherein the means for selectively coupling includes a timer for measuring a time period after a signal is received by the circuit. - View Dependent Claims (6, 7, 8)
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9. A sensor for sending message packets to a system controller, comprising:
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a circuit board operably connected to a condition-sensing device; and a transmitter connected with the circuit board by at least one pin; the transmitter including a first pull-up resistor having a predetermined resistance value, a second pull-up resistor having a resistance value lower than the first resistor, and a switching circuit for selectively connecting one of the first and second resistors to the pin when a signal is received on the pin, wherein the sensor is battery-powered, the first resistance value is selected to minimize battery drain and the second resistance value is selected to reduce dendrites on the circuit board when a signal is received.
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10. A sensor for sending message packets to a system controller, comprising:
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a circuit board operably connected to a condition-sensing device; and a transmitter connected with the circuit board by at least one pin, the transmitter including a first pull-up resistor having a predetermined resistance value, a second pull-up resistor having a resistance value lower than the first resistor, and a switching circuit for selectively connecting one of the first and second resistors to the pin when a signal is received on the pin, wherein the switching circuit includes a timer for measuring a time period after a signal is received on the pin. - View Dependent Claims (11, 12)
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13. In a battery-powered transmitter for sending message packets, the transmitter having at least one input pin for receiving signals from a circuit, a method for reducing parasitic parallel resistance, comprising:
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periodically coupling a first resistor to the input pin to detect signals from the circuit; and coupling a second resistor to the input pin after a signal is detected when the first resistor is coupled with the input pin. - View Dependent Claims (14, 15, 16)
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17. A sensor apparatus comprising:
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a circuit for sensing a signal; a first pull-up resistor having a first resistance value; a second pull-up resistor having a second resistance value less than the first resistance value; means for coupling the first pull-up resistor to the circuit to apply a first current for sensing the signal; and means for coupling the second pull-up resistor to the circuit to apply a second current to alleviate a condition causing unsatisfactory sensing of the signal after application of the first current. - View Dependent Claims (18)
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19. An apparatus for reducing short circuits in a battery-powered sensor circuit, comprising:
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a first pull-up resistor having a first resistance value; a second pull-up resistor having a second resistance value lower than the first resistance value; and means for selectively coupling the resistors with the circuit, wherein the first resistance value of the first pull-up resistor is selected to minimize battery drain and the second resistance value of the second pull-up resistor is selected to reduce parallel parasitic resistance in the circuit. - View Dependent Claims (20)
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21. A method for maintaining satisfactory signal sensing in a sensor circuit, the method comprising:
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coupling a first pull-up resistor having a first resistance value to apply a first current to the sensor circuit for sensing the signal; and coupling a second pull-up resistor having a second resistance value less than the first resistance value to apply a second current to the sensor circuit to alleviate a condition causing unsatisfactory sensing of the signal. - View Dependent Claims (22, 23, 24)
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25. A sensor device comprising:
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a sensor circuit for sensing a signal; a first current circuit coupled to apply a first current to the sensor circuit during sensing of the signal; a second current circuit coupled to apply a second current to the sensor circuit to alleviate a condition causing unsatisfactory sensing of the signal, wherein the second current is greater than the first current and is sufficient to reduce dendrites in the sensor circuit.
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26. A method for maintaining satisfactory signal sensing in a sensor circuit, the method comprising:
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applying a first current to the sensor circuit during sensing of the signal; applying a second current to the sensor circuit to alleviate a condition causing unsatisfactory sensing of the signal, wherein the second current is greater than the first current and is sufficient to reduce dendrites in the sensor circuit.
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Specification