Automotive current sensor
First Claim
1. An essentially temperature invarient current sensor suitable for use in an automobile to measure a current delivered from a source of electrical energy to a load and configured upon occurrence of internal failure to indicate a maximum current level, said sensor comprising:
- a shunt assembly connectable in line with said source and said load, said shunt assembly having at least one low-resistance shunt element constructed of a material having characteristically small resistance drift due to variations in ambient temperature;
a difference mode amplifier having a first input electrically connected to a first terminal side of said shunt and a second input electrically connected to a second terminal side of said shunt element, said difference mode amplifier producing a difference signal representative of a voltage drop across said shunt element due to a flow of current;
said difference mode amplifier further including means for producing upon disconnection of said first and second inputs from said shunt element a voltage difference sufficient to indicate said maximum current level;
scaling circuitry electrically connected to receive said difference signal and operable to produce during normal operation of said difference mode amplifier a ratiometric current level signal; and
said scaling circuitry further operable during failure of said difference mode amplifier to produce a signal indicating said maximum current level.
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Accused Products
Abstract
A high-amperage current sensor is disclosed which is suitable for use in an automotive electrical system and which is operatively unaffected by changes in ambient temperature. The current sensor utilizes a shunt assembly having at least one low-resistance shunt element connectable in line between a source of electrical energy and a load. Circuitry preferably configured on an application specific integrated circuit measures voltage drop across the shunt element due to current flow. As a result, an output signal is produced which may be fed to external circuitry for further processing. In presently preferred embodiments, the sensor may comprise analog circuitry producing an analog output signal and/or digital circuitry producing a digital output signal.
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Citations
8 Claims
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1. An essentially temperature invarient current sensor suitable for use in an automobile to measure a current delivered from a source of electrical energy to a load and configured upon occurrence of internal failure to indicate a maximum current level, said sensor comprising:
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a shunt assembly connectable in line with said source and said load, said shunt assembly having at least one low-resistance shunt element constructed of a material having characteristically small resistance drift due to variations in ambient temperature; a difference mode amplifier having a first input electrically connected to a first terminal side of said shunt and a second input electrically connected to a second terminal side of said shunt element, said difference mode amplifier producing a difference signal representative of a voltage drop across said shunt element due to a flow of current; said difference mode amplifier further including means for producing upon disconnection of said first and second inputs from said shunt element a voltage difference sufficient to indicate said maximum current level; scaling circuitry electrically connected to receive said difference signal and operable to produce during normal operation of said difference mode amplifier a ratiometric current level signal; and said scaling circuitry further operable during failure of said difference mode amplifier to produce a signal indicating said maximum current level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification