Sensor device

Patent metadata

Field	Value
Publication number	US-9941686-B2
Application number	US-201415029639-A
Country	US
Kind code	B2
Filing date	Oct 3, 2014
Priority date	Oct 23, 2013
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

Provided is a sensor device that suppresses a malfunction caused by a negative surge or a voltage drop. A sensor device includes a sensor element having an electrical characteristic varying according to a physical amount, a signal processing circuit configured to process an output signal of the sensor element, a transistor element interposed between a power source terminal and the signal processing circuit, a resistive element configured to connect a drain and a gate of the transistor element, or a collector and a base of the transistor element, and an element having threshold voltage for connecting the gate or the base of the transistor element to a GND. The element regulates current flowing from the resistive element in a direction of the GND, in a case in which supply voltage to the signal processing circuit falls below the threshold voltage.

First claim

The invention claimed is:

1. A sensor device comprising:
a sensor element having an electrical characteristic varying according to a physical amount;
a signal processing circuit configured to process an output signal of the sensor element;
a transistor element interposed between a power source terminal and the signal processing circuit;
a resistive element configured to connect a gate of the transistor element or a base of the transistor element to a wire connecting the transistor element and the signal processing circuit; and
an element having threshold voltage for connecting the gate or the base of the transistor element to a GND,
wherein the element maintains electrical charge accumulated in the signal processing circuit by limiting current flowing from the resistive element in a direction of the GND and switching the transistor element off, in a case in which supply voltage to the signal processing circuit falls below the threshold voltage.

2. The sensor device according to claim 1 ,
wherein the transistor element is a first field-effect transistor, and
wherein a source of the first field-effect transistor and the power source terminal are connected, a drain of the first field-effect transistor and the signal processing circuit are connected, and a gate of the first field-effect transistor is connected to the GND via the element.

3. A sensor device comprising:
a sensor element having an electrical characteristic varying according to a physical amount;
a signal processing circuit configured to process an output signal of the sensor element;
a transistor element interposed between a power source terminal and the signal processing circuit;
a resistive element configured to connect a gate of the transistor element, or a collector and a base of the transistor element; and
an element having threshold voltage for connecting the gate or the base of the transistor element to a GND,
wherein the element regulates current flowing from the resistive element in a direction of the GND, in a case in which supply voltage to the signal processing circuit falls below the threshold voltage,
wherein the transistor element is a first field-effect transistor,
wherein a source of the first field-effect transistor and the power source terminal are connected, a drain of the first field-effect transistor and the signal processing circuit are connected, and a gate of the first field-effect transistor is connected to the GND via the element,
wherein the element is a second field-effect transistor, and
wherein a source of the second field-effect transistor and the gate of the first field-effect transistor are connected, and a drain and a gate of the second field-effect transistor and the GND are connected.

4. The sensor device according to claim 3 ,
wherein a well of the first field-effect transistor is connected to a drain of the first field-effect transistor, and a well of the second field-effect transistor is connected to the source of the second field-effect transistor.

5. The sensor device according to claim 2 ,
wherein the element is a transistor circuit including a plurality of series-connected field-effect transistors, and
wherein a source of the transistor circuit and the gate of the first transistor are connected, and a drain and a gate of the transistor circuit and the GND are connected.

6. The sensor device according to claim 2 ,
wherein the element is a PN junction diode, and
wherein an anode of the diode and the gate of the first field-effect transistor are connected, and a cathode of the diode and the GND are connected.

7. The sensor device according to claim 2 ,
wherein the element is a diode circuit including a plurality of series-connected PN junction diodes, and
wherein an anode of the diode circuit and the gate of the first field-effect transistor are connected, and a cathode of the diode circuit and the GND are connected.

8. The sensor device according to claim 1 ,
wherein the transistor element is a first PNP transistor, and
wherein an emitter of the first PNP transistor and the power source terminal are connected, a collector of the first PNP transistor and the signal processing circuit are connected, and a base of the first PNP transistor is connected to the GND via the element.

9. A sensor device comprising:
a sensor element having an electrical characteristic varying according to a physical amount;
a signal processing circuit configured to process an output signal of the sensor element;
a transistor element interposed between a power source terminal and the signal processing circuit;
a resistive element configured to connect a drain and a gate of the transistor element, or a collector and a base of the transistor element; and
an element having threshold voltage for connecting the gate or the base of the transistor element to a GND,
wherein the element regulates current flowing from the resistive element in a direction of the GND, in a case in which supply voltage to the signal processing circuit falls below the threshold voltage,
wherein the transistor element is a first PNP transistor,
wherein an emitter of the first PNP transistor and the power source terminal are connected, a collector of the first PNP transistor and the signal processing circuit are connected, and a base of the first PNP transistor is connected to the GND via the element,
wherein the element is a second PNP transistor, and
wherein an emitter of the second PNP transistor and the base of the first PNP transistor are connected, and a collector and a base of the second PNP transistor are connected to the GND.

10. The sensor device according to claim 8 ,
wherein the element is a transistor circuit including a plurality of series-connected PNP transistors, and
wherein an emitter of the transistor circuit and the base of the first PNP transistor are connected, and a collector and a base of the transistor circuit and the GND are connected.

11. The sensor device according to claim 8 ,
wherein the element is a PN junction diode, and
wherein an anode of the diode and the base of the first PNP transistor are connected, and a cathode of the diode and the GND are connected.

12. The sensor device according to claim 8 ,
wherein the element is a diode circuit including a plurality of series-connected PN junction diodes, and
wherein an anode of the diode circuit and the base of the first PNP transistor are connected, and a cathode of the diode circuit and the GND are connected.

13. The sensor device according to claim 1 ,
wherein the sensor device includes a capacitor series-connected to the signal processing circuit.

14. The sensor device according to claim 1 ,
wherein threshold voltage of the element is a voltage value equal to or larger than information stored in a memory of the processing circuit.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Asano Satoshi
• Matsumoto Masahiro
• Nakano Hiroshi
• Tashiro Shinobu

Classifications

• H01L28/20

  Electricity · mapped topic

• H01L29/861

  Electricity · mapped topic

• H01L28/40

  Electricity · mapped topic

• G01R15/146

  Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop (if no voltage isolation is involved G01R1/203 or G01R19/0092) · CPC title

• H01L27/0629

  Electricity · mapped topic