# US 2013/0278236 A1 · Current limiting circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278236 A1 - Document ID: US20130278236A1 - Status: Published application - Kind: A1 - Application number: 13/923,017 - Filed: 2013-06-20 - Published: 2013-10-24 - Earliest claimed: 2010-02-10 - Assignees: Renesas Electronics Corporation - Applicants: Renesas Electronics Corporation - Inventors: Akihiro NAKAHARA - Web page: https://patentgrep.com/patent/US20130278236A1 ## CPC - G05F 1/10: Regulating voltage or current (G05F1/02 takes precedence) - H03K 17/0822: {in field-effect transistor switches} - H10W 90/756: {between a chip and a stacked lead frame, conducting package substrate or heat sink} - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract An exemplary aspect of the present invention is a current limiting circuit including: an output transistor that controls a current flowing to a load from a power supply; a current sense transistor through which a current dependent on a current flowing through the output transistor flows; a sense resistor connected in series with the current sense transistor; a potential difference detection unit that detects a potential difference generated between both ends of the sense resistor; a constant current generation unit that supplies a constant current to the potential difference detection unit; and a control unit that controls a conduction state of the output transistor based on a control voltage generated based on the potential difference and the constant current, in which the sense resistor is disposed so as to surround the potential difference detection unit. ## Claims ### Claim 1 A power supply control unit comprising: an output transistor formed on a semiconductor chip, the output transistor controlling a current flowing to a load from a power supply; a sense transistor and a metal resistor coupled in series with each other, sense transistor and the metal resistor being formed on the semiconductor chip and coupled in parallel with the output transistor, a current dependent on a current flowing through the output transistor being flowed through the sense transistor and the metal resistor; a potential difference detection unit detecting a potential difference generated across the metal resistor, the potential difference detection unit being substantially surrounded by the metal resistor; and a control unit controlling a conduction state of the output transistor based on the potential difference. ### Claim 2 (depends on 1) The power supply control unit according to claim 1, further comprising: a current generation unit supplying a current to the potential difference detection unit, a control voltage being generated based on the potential difference and the constant current, a conduction state of the output transistor being controlled based on the control voltage. ### Claim 3 (depends on 1) The power supply control unit according to claim 1, wherein the metal resistor is formed of aluminum, copper, or an alloy containing at least one of these elements as a main component. ### Claim 4 The power supply control unit according to Claim I, wherein the metal resistor is formed in a zig-zag manner or a serpentine manner so that a convex portion and a concave portion with respect to the potential difference detection unit are continuously formed. ### Claim 5 (depends on 1) The power supply control unit according to claim 1, wherein the metal resistor is integrally formed with a heat radiation fin. ### Claim 6 (depends on 1) The power supply control unit according to claim 1, wherein the metal resistor and the potential difference detection unit are disposed near the output transistor. ### Claim 7 (depends on 1) The power supply control unit according to claim 1, wherein the current generation unit includes first and second current sources, and the potential difference detection unit includes: a first diode group provided between the first current source and a node between the sense transistor and the metal resistor; and a second diode group provided between the second current source and a node between the metal resistor and the output transistor. ### Claim 8 (depends on 7) The power supply control unit according to claim 7, wherein the control unit includes: an amplifier generating the control voltage; and a control transistor provided between a control node and a source node of the output transistor, a conduction state of the control transistor being controlled based on the control voltage. ### Claim 9 (depends on 1) The power supply control unit according to claim 1, wherein the current generation unit includes first and second current source transistors, and the potential difference detection unit includes: a first transistor provided between the first current source transistor and a node between the sense transistor and the metal resistor; and a second transistor provided between the second current source transistor and a node between the metal resistor and the output transistor, control nodes of the first and second transistor being mutually coupled. ### Claim 10 (depends on 9) The power supply control unit according to claim 9, wherein the control unit includes a control transistor provided between a control node and a source node of the output transistor, a conduction stale of the control transistor being controlled based on an output voltage of the potential difference detection unit. ### Claim 11 (depends on 3) The power supply control unit according to claim 3, wherein a source node of the output transistor and a source node of the sense transistor comprises a same material of the metal resistor.