# US 7,466,139 B2 · Method to determine current detection circuit failure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,466,139 B2 - Document ID: US7466139B2 - Status: Granted - Kind: B2 - Application number: 11/500,398 - Filed: 2006-08-08 - Published: 2007-02-22 - Granted: 2008-12-16 - Earliest claimed: 2005-08-17 - Assignees: Sanyo Electric Co., Ltd. - Inventors: Kimihiko Furukawa - Web page: https://patentgrep.com/patent/US7466139B2 ## CPC - G01R 31/2829: {Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method of determining current detection circuit failure determines failure of a current detection circuit that is connected to positive and negative sides of a power source and that issues a voltage corresponding to detected current at an output terminal. The method of determining failure cuts-off either one of the current detection circuit connections to the positive and negative sides of the power source, detects output voltage from the output terminal, and determines proper operation or failure of the current detection circuit. ## Claims ### Claim 1 A method of determining current detection circuit failure of a current detection circuit that is connected to a positive side and a negative side of a power source, the current detection circuit being operable to issue a voltage corresponding to a detected current at an output terminal, the method comprising: cutting off the positive-side of the power source so that the current detection circuit is supplied only by the negative-side of the power source; and comparing output voltage issued from the output terminal of the current detection circuit to a reference voltage, wherein the current detection circuit is determined to be operating properly if the output terminal voltage is more negative than the reference voltage, and current detection circuit failure is determined when the output terminal voltage is the reference voltage or within a specified voltage range. ### Claim 2 (depends on 1) The method of determining current detection circuit failure as recited in claim 1, wherein the current detection circuit detects current via a magnetic flux sensor that senses magnetic flux generated by the current to be detected. ### Claim 3 (depends on 1) The method of determining current detection circuit failure as recited in claim 1, wherein current is detected by the current detection circuit that outputs a voltage that is proportional to the detected current. ### Claim 4 (depends on 1) The method to determine current detection circuit failure as recited in claim 1, wherein current is detected by a current detection circuit that changes output voltage polarity depending on the direction of the detected current flow. ### Claim 5 (depends on 1) The method to determine current detection circuit failure as recited in claim 1, wherein current is detected by a current detection circuit with a circuit that connects reverse biased diodes between the output terminal and the positive and negative power source. ### Claim 6 (depends on 5) The method to determine current detection circuit failure as recited in claim 5, wherein current is detected by a current detection circuit with a circuit that connects a sensor circuit load between the positive-side and negative-side power source. ### Claim 7 (depends on 1) The method of determining current detection circuit failure as recited in claim 1, wherein current detection circuit failure is determined while supplying a bias voltage at an output-side of the current detection circuit. ### Claim 8 (depends on 1) The method of determining current detection circuit failure as recited in claim 1, wherein the current detection circuit is installed in a vehicle that is a hybrid car. ### Claim 9 (depends on 8) The method of determining current detection circuit failure as recited in claim 8, wherein immediately after the car ignition switch is turned ON, current detection circuit failure is determined in a condition with no battery current flow. ### Claim 10 (depends on 1) The method of determining current detection circuit failure as recited in claim 1, wherein current detection circuit offset is detected for a current detection circuit that is operating properly. ### Claim 11 A method of determining current detection circuit failure of a current detection circuit that is connected to a positive side and a negative side of a power source, the current detection circuit being operable to issue a voltage corresponding to a detected current at an output terminal, the method comprising: cutting off the negative-side of the power source so that the current detection circuit is supplied only by the positive-side of the power source; and comparing the output voltage issued from the output terminal of the current detection circuit to a reference voltage, wherein the current detection circuit is determined to be operating properly if the output terminal voltage is more positive than the reference voltage, and current detection circuit failure is determined when the output terminal voltage is the reference voltage or within a specified voltage range. ### Claim 12 (depends on 11) The method of determining current detection circuit failure as recited in claim 11, wherein the current detection circuit detects current via a magnetic flux sensor that senses magnetic flux generated by the current to be detected. ### Claim 13 (depends on 11) The method of determining current detection circuit failure as recited in claim 11, wherein the current detection circuit outputs a voltage that is proportional to the detected current. ### Claim 14 (depends on 11) The method of determining current detection circuit failure as recited in claim 11, wherein the current detection circuit changes output voltage polarity depending on the direction of the detected current flow. ### Claim 15 (depends on 12) The method of determining current detection circuit failure as recited in claim 12, wherein the current detection circuit includes a circuit that connects reverse biased diodes between the output terminal and the positive side and negative side of the power source. ### Claim 16 A method of determining current detection circuit failure of a current detection circuit that is connected to a positive side and a negative side of a power source, the current detection circuit being operable to issue a voltage corresponding to a detected current at an output terminal, the method comprising: switching the current detection circuit from a connection to the positive side and the negative side of the power source to a state in which the positive-side power connection is cut-off, and supplying the current detection circuit only with current from the negative side of the power source; and detecting a change in the output voltage issued from the output terminal of the current detection circuit, wherein the current detection circuit is determined to be operating properly when the output voltage shifts negative. ### Claim 17 (depends on 16) The method of determining current detection circuit failure as recited in claim 16, wherein the current detection circuit outputs a voltage that is proportional to the detected current. ### Claim 18 (depends on 16) The method of determining current detection circuit failure as recited in claim 16, wherein the current detection circuit changes output voltage polarity depending on the direction of the detected current flow. ### Claim 19 A method of determining current detection circuit failure of a current detection circuit that is connected to a positive side and a negative side of a power source, the current detection circuit being operable to issue a voltage corresponding to a detected current at an output terminal, the method comprising: switching the connection of the current detection circuit from the positive and negative sides of the power source to a state in which the negative-side power source connection is cut-off, and supplying the current detection circuit with only current from the positive-side of the power source; and detecting a change in the output voltage issued from the output terminal of the current detection circuit, wherein the current detection circuit is determined to be operating properly when output voltage shifts positive. ### Claim 20 (depends on 19) The method of determining current detection circuit failure as recited in claim 19, wherein the current detection circuit outputs a voltage that is proportional to the detected current.