Switch input current circuit
AssigneeRobert Bosch GmbH
InventorsScott Haydon Turner, Matthew David Fenwick
Life of this patent
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Abstract
A method and corresponding apparatus for improving the power consumption of a switch input circuit is described having resistive elements, the method including the steps of providing a wetting current to at least one switch through a respective resistive element, and modulating the wetting current with a pulse width modulation signal to provide a reduced average voltage applied to the respective resistive element, and thereby reduce the power consumption of the circuit.
Claims18
A method of providing a wetting current to at least one switch through a corresponding resistor element using a switch input circuit and a current source, the method comprising:
- detecting a number of closed switches connected to the switch input circuit;
- adjusting a pulse-width modulation signal in response to a detected number of closed switches;
- and
- modulating the wetting current as a function of the pulse-width modulation signal to reduce an average power consumption of the corresponding resistor element.
A switch input circuit comprising:
- at least one switch;
- at least one resistor element;
- a current source to provide a wetting current to the at least one switch through a corresponding resistor element of the at least one resistor element;
- a modulation arrangement to modulate the wetting current to reduce an average power consumption of the corresponding resistor element, the modulation arrangement including a micro-controller configured to generate a pulse-width modulation signal;
- a detection arrangement to detect a number of closed switches connected to the switch-input circuit;
- and
- an adjusting arrangement to adjust the pulse-width modulation signal in response to a detected number of closed switches.
A switch input circuit comprising:
- a current source to supply a wetting current to at least one switch;
- and
- a pulse-width modulation arrangement to provide a pulse-width modulation signal to modulate the wetting current to reduce an average wetting current supplied to the at least one switch to provide improved power consumption.
A method of improving power consumption characteristics of a switch input circuit, comprising:
- providing a wetting current to at least one switch;
- and
- modulating the wetting current with a pulse-width modulation signal to reduce an average wetting current provided to the at least one switch.
A switch input circuit, comprising:
- at least one switch;
- at least one resistor element;
- a voltage supply;
- a current source to provide a wetting current to the at least one switch through a corresponding resistor element of the at least one resistor element;
- a modulation arrangement to modulate the wetting current to reduce an average power consumption of the corresponding resistor element, the modulation arrangement including a micro-controller configured to determine a voltage level of the voltage supply and a voltage level of a respective resistive element, and to generate a pulse-width modulation signal;
- a transistor having a base, an emitter, and a collector, wherein the pulse-width modulation signal is supplied to the base to allow periodically a current to flow through the emitter and the collector into the switch input circuit in accordance with a duty cycle of the pulse-width modulation signal;
- a detection arrangement arranged in the micro-controller to detect a number of closed switches connected to the switch-input circuit;
- and
- an adjusting arrangement to adjust the pulse-width modulation signal in response to a detected number of closed switches.
A method of providing a wetting current to at least one switch through a corresponding resistor element using a switch input circuit and a current source, the method comprising:
- detecting a number of closed switches connected to the switch input circuit;
- adjusting a pulse-width modulation signal in response to a detected number of closed switches;
- modulating the wetting current as a function of the pulse-width modulation signal to reduce an average power consumption of the corresponding resistor element;
- supplying the pulse-width modulation signal to a base of a transistor to allow periodically the wetting current to flow through an emitter and a collector of the transistor into the switch input circuit in accordance with a duty cycle of the pulse-width modulation signal;
- increasing the duty cycle of the pulse-width modulation signal if the sensed number of closed switches increases;
- determining a voltage level of a voltage supply of the switch input circuit;
- sensing the voltage level using an analog-to-digital converter to determine a digital value representative of the voltage level;
- determining, from the digital value, which of a plurality of predetermined voltage ranges the voltage level of the voltage supply falls within;
- and
- adjusting the duty cycle of the pulse-width modulation signal depending on a determined voltage range of the voltage supply.
Dependencies are inferred from the claim text.