CONFIGURATION OF INTEGRATED CURRENT FLOW SENSOR

• US 20180080957A1
• Filed: 09/22/2016
• Published: 03/22/2018
• Est. Priority Date: 09/22/2016
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Sander, Rainald, Leisenheimer, Stephan, Mieslinger, Stefan
• Granted Patent: US 10,802,053 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 15/146 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 Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor

Abstract

This disclosure is directed to techniques that may accurately determine the amount of current flowing through a power switch circuit by measuring the voltage across the inherent impedance of the circuit connections. One connection may include a low impedance connection between the power switch output and ground, where the low impedance connection may be on the order of milliohms. By using a four-wire measurement, the sensing connections are not in the current path, so the measured value may not be affected by the current. The connection that makes up the current path can be accomplished with a variety of conductive materials. Conductive materials may have a temperature coefficient of resistivity that may impact a measurement of electric current as the temperature changes. Measuring the temperature of the current path, along with the voltage across the connection, may allow a more accurate current measurement.

Claims

1. A circuit comprising:

a power switch, wherein the power switch includes a power switch output and a power switch input;

a current path, wherein the current path includes an inherent impedance and the current path connects the power switch output to a ground;

a first current sense terminal and a second current sense terminal, wherein the first current sense terminal and the second current sense terminal are configured to determine an amount of current in the current path; and

a temperature sensor, wherein the temperature sensor is configured to determine the temperature of the current path.

2. The circuit of claim 1, wherein the first current sense terminal connects to the power switch output and the second current sense terminal connects to the ground.

3. The circuit of claim 1,

wherein the current path is a first current path that includes a first inherent resistance and the temperature sensor is a first temperature sensor;

and further comprising;

a second current path, wherein the second current path includes a second inherent resistance and the second current path connects the power switch input to a supply voltage;

a third current sense terminal and a fourth current sense terminal, wherein the third current sense terminal and the fourth current sense terminal are configured to determine an amount of current in the second current path; and

a second temperature sensor, wherein the second temperature sensor is configured to determine the temperature of the second current path.

4. The circuit of claim 3, wherein the third current sense terminal connects to the power switch input and the fourth current sense terminal connects to the supply voltage.

5. The circuit of claim 1, wherein the power switch is a first power switch, and further comprising a second power switch, wherein the second power switch includes a second power switch output and a second power switch input, and wherein:

the second power switch output connects to the first power switch input,

the second power switch input connects to a supply voltage.

6. The circuit of claim 5,

wherein the current path is a first current path that includes a first inherent resistance and the temperature sensor is a first temperature sensor;

wherein the second power switch input connection to the supply voltage comprises a second current path with a second inherent impedance, and further comprising;

a third current sense terminal and a fourth current sense terminal, wherein the third current sense terminal and the fourth current sense terminal are configured to determine an amount of current in the second current path; and

a second temperature sensor, wherein the second temperature sensor is configured to determine the temperature of the second current path.

7. The circuit of claim 6, wherein the third current sense terminal connects to the power switch input and the fourth current sense terminal connects to the supply voltage.

8. The circuit of claim 2, further comprising an output terminal of the circuit, wherein the current path connects the power switch output to the output terminal of the circuit, and the second current sense terminal connects to the output terminal of the circuit.

9. The circuit of claim 1 wherein the power switch is a metal oxide semiconductor field effect transistor (MOSFET).

10. A system comprising:

a measuring unit; and

circuit comprising;

a power switch, wherein the power switch includes a power switch output and a power switch input;

a current path, wherein the current path includes an inherent impedance and the current path connects the power switch output to a ground;

a first current sense terminal and a second current sense terminal, wherein the first current sense terminal and the second current sense terminal are configured to detect an amount of current in the current path; and

a temperature sensor, wherein the temperature sensor is configured to detect the temperature of the current path; and

wherein the measuring unit connects to the first current sense terminal, the second current sense terminal and the temperature sensor.

11. The system of claim 10, wherein the power switch further comprises a power switch gate and the measuring unit further comprises a processor and a gate control output, wherein the gate control output connects to the power switch gate, and the processor is configured to:

monitor the first current sense terminal and the second current sense terminal and determine the amount of current in the current path;

in response to determining the amount of current in the current path, control the amount of current in the current path by outputting a signal to the power switch gate.

12. The system of claim 11, wherein the processor is further configured to:

monitor the temperature sensor to determine the temperature of the current path;

in response to determining the temperature of the current path, control the amount of current in the current path by outputting a signal to the power switch gate.

13. The system of claim 12, wherein the current path comprises a current path material, the inherent impedance of the current path depends on the current path material and the processor is further configured to control the amount of current in the current path based at least in part on the current path material.

14. The system of claim 10, further comprising a current path output terminal, wherein the current path connects the power switch output to the current path output terminal, and the second current sense terminal connects to the current path output terminal.

15. The system of claim 13, wherein the current path material comprises a metal or alloy composition.

16. The system of claim 15, wherein the metal or alloy composition comprises one or more of copper or aluminum.

17. The system of claim 13, wherein the current path material includes a temperature coefficient of impedance, and the processor is further configured to determine a corrected value of the amount of current in the current path based at least in part on the temperature coefficient of impedance of the current path material.

18. A method for determining a current through a power switch, the method comprising,

monitoring, by a processor of a measuring unit, a first current sense terminal and a second current sense terminal, wherein:

the first current sense terminal connects to an output of the power switch,

the second current sense terminal connects to a ground, and

a current path connects the output of the power switch to the ground and the current path includes an inherent impedance;

determining, by the processor, the amount of current in the current path, based on the inherent impedance of the current path;

monitoring, by the processor, a temperature sensor, wherein the temperature sensor is configured to detect the temperature of the current path;

determining, by the processor, the temperature of the current path;

in response to determining, by the processor, the temperature of the current path, further determining, by the processor, a corrected value of the amount of current in the current path.

19. The method of claim 18, wherein the current path comprises a current path material, and the current path material includes a temperature coefficient of impedance, the method further comprising determining, by the processor, the corrected value of the amount of current in the current path based at least in part on the temperature coefficient of impedance of the current path material.

20. The method of claim 18, wherein the power switch comprises a power switch gate, the method further comprising controlling, by the processor, the amount of current in the current path by outputting a signal to the power switch gate.