Non-isolated type voltage sensor
First Claim
1. A non-isolated type voltage sensor provided between a battery and a circuit having a pull-up resister which is connected to a reference power supply and a cable, the non-isolated type voltage sensor comprising:
- a voltage dividing circuit comprising a plurality of resistors connected in series such that the voltage dividing circuit is connected to said battery in parallel, so as to obtain a voltage proportional to a terminal voltage of said battery and less than said reference voltage at a desired voltage dividing point of said plural resistors;
a voltage follower which receives an input of a voltage from the voltage dividing point of said voltage dividing circuit; and
a voltage-current conversion circuit in which an input thereof is connected to an output of said voltage follower while an output thereof is connected to said cable so that a current proportional to a low impedance output voltage obtained through said voltage follower flows to the ground through an output resistor.
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Accused Products
Abstract
A non-isolated type voltage sensor is provided between a battery of less than 60 V and a circuit having a resistor, an end of which is connected to a wire harness while another end is connected to a reference power supply. The non-isolated type voltage sensor includes voltage dividing circuits, which include plural resistors connected in series such that those resistors are connected to the battery in parallel so as to obtain a voltage proportional to a terminal voltage of the battery and less than the reference voltage at a desired voltage dividing point of the plural resistors, a voltage follower, which receives an input of a voltage from the voltage dividing point of the voltage dividing circuit, and a voltage-current conversion circuit including a FET so as to supply a current proportional to a low impedance output voltage obtained through the voltage follower to the ground through a resistor.
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Citations
5 Claims
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1. A non-isolated type voltage sensor provided between a battery and a circuit having a pull-up resister which is connected to a reference power supply and a cable, the non-isolated type voltage sensor comprising:
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a voltage dividing circuit comprising a plurality of resistors connected in series such that the voltage dividing circuit is connected to said battery in parallel, so as to obtain a voltage proportional to a terminal voltage of said battery and less than said reference voltage at a desired voltage dividing point of said plural resistors;
a voltage follower which receives an input of a voltage from the voltage dividing point of said voltage dividing circuit; and
a voltage-current conversion circuit in which an input thereof is connected to an output of said voltage follower while an output thereof is connected to said cable so that a current proportional to a low impedance output voltage obtained through said voltage follower flows to the ground through an output resistor. - View Dependent Claims (2)
a field effect transistor a source of which is connected to said cable while a drain thereof is connected to said output resistor;
an output resistor which is connected to a drain of said field effect transistor and said ground, the output resistor having a resistance higher than a resistance of said pull-up resistor; and
an amplifier in which an output of said voltage follower is connected to a non-inverted input thereof, an inverted input thereof is connected to said output resistor and an output thereof is connected to a gate of said field effect transistor.
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3. A non-isolated type voltage sensor provided between a battery and a circuit having a pull-up resistor which is connected to ground and a cable, including:
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a voltage detecting circuit for obtaining a voltage proportional to a voltage of said battery at a voltage dividing point and supplying a first current proportional to a low impedance output voltage obtained from a voltage at said voltage dividing point to the ground through a first output resistor; and
a voltage-current conversion circuit for supplying a second current proportional to a voltage signal determined by said first current to said cable through a second output resistor. - View Dependent Claims (4, 5)
said voltage detecting circuit comprising: a voltage dividing circuit containing a plurality of resistors connected in series such that the voltage dividing circuit is connected to said battery in parallel, so as to obtain a voltage proportional to a terminal voltage of said battery and less than said reference voltage at a desired voltage dividing point of said plural resistors;
a voltage follower which receives an input of a voltage at the voltage dividing point of said voltage dividing circuit; and
a first voltage-current conversion circuit in which an input thereof is connected to an output of said voltage follower so that said first current obtained through said voltage follower and proportional to a low impedance output voltage flows to the ground through said first output resistor, said voltage-current conversion circuit being comprised of a second voltage-current conversion circuit in which a second pull-up resistor having the same resistance as said first output resistor, said pull-up resistor being connected to the reference power supply, and supplies said second current proportional to a low impedance output voltage obtained from a voltage signal at the connecting point between said second pull-up resister and said first voltage-current conversion circuit to said cable through said second output resistor.
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5. A non-isolated type voltage sensor according to claim 4 wherein said first voltage-current conversion circuit comprises:
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a first field effect transistor a source of which is connected to an input of said second voltage-current conversion circuit while a drain thereof is connected to said first output resistor;
a first output resistor which is connected to a drain of said first field effect transistor and said ground; and
a first amplifier in which an output of said voltage follower is connected to a non-inverted input thereof, an inverted input thereof is connected to said first output resistor and an output thereof is connected to a gate of said field effect transistor, said second voltage-current conversion circuit comprising;
a second pull-up resistor which is connected to said reference power supply and a source of said first field effect transistor;
a second output resistor which is connected to said reference power supply;
a second field effect transistor a source of which is connected to said second output resistor while a drain thereof is connected to said cable; and
a second amplifier in which a non-inverted input thereof is connected to a source of said first field effect transistor, a non-inverted input thereof is connected to said second output resistor and a source of said second field effect transistor and an output thereof is connected to a gate of said second field effect transistor.
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Specification