# US 2021/0344191 A1 · Systems and methods to cable shield fault detection and protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344191 A1 - Document ID: US20210344191A1 - Status: Published application - Kind: A1 - Application number: 17/233,829 - Filed: 2021-04-19 - Published: 2021-11-04 - Earliest claimed: 2020-04-29 - Assignees: Maxim Integrated Products, Inc. - Applicants: Maxim Integrated Products, Inc. - Inventors: Anurag Veerabathini; Punith Kumar Reddy Surkanti; Jan F. Swidzinski; Kevin John Schemansky - Web page: https://patentgrep.com/patent/US20210344191A1 ## CPC - G01R 31/58: Testing of lines, cables or conductors (testing of electric windings G01R31/72) - H02H 7/228: {for covered wires or cables} - G01R 19/16576: {comparing DC or AC voltage with one threshold (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence)} - G01R 31/1263: {of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation} - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - G01R 31/52: Testing for short-circuits, leakage current or ground faults - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract Described are system and method embodiments for shield fault detection to protect the cable, components and other circuits connected to the cable shield, and to avoid high short circuit currents flowing from a power source to ground during unexpected events. A threshold voltage detector and a slope detector may be used to sense the voltage on a shield pin switchably coupled to ground via a shield ground. Method embodiments to distinguish the shield ground switch current caused by a shield fault from normal operation are also discussed. In certain situations, a weak ground path is established first to sense or identify a valid attachment on the cable before establishing a strong ground path. The disclosed embodiments, separately or in combination, may effectively detect shield fault with improved performance. ## Claims ### Claim 1 A method of shield fault detection, comprising: detecting a rate of voltage change on a shield pin of a cable connection interface; comparing the rate of voltage change to a reference slope; detecting whether or not a current is flowing through a power pin of the cable connection interface; disconnecting a ground path of the shield pin based on the rate of voltage change being above the reference slope and the current through the power pin not being detected; and connecting the ground path based on the rate of voltage change being above the reference slope and the current through the power pin being detected. ### Claim 2 (depends on 1) The method of claim 1 further comprising connecting the ground path of the shield pin based on the rate of voltage change being below the reference slope. ### Claim 3 (depends on 1) The method of claim 1 wherein comparing the rate of voltage change to the reference slope includes comparing the rate of voltage change to a linear reference slope. ### Claim 4 (depends on 1) The method of claim 1 wherein detecting the rate of voltage change on the shield pin of the cable connection interface includes detecting the rate of voltage change on the shield pin of a type-A USB port, a type-B USB port, a type-C USB port, a mini USB port, a micro USB port, or a lightning connector. ### Claim 5 (depends on 1) The method of claim 1 wherein disconnecting the ground path includes providing a signal with a logic control module to disconnect a switch between the shield pin and a ground. ### Claim 6 A method of establishing a weak ground path, comprising: disabling a first ground path for a shield pin of a cable connection interface, the first ground path including a first switch; enabling a second ground path for the shield pin, the second ground path comprises a second switch, and the second ground path having a higher resistance than the first ground path; determining a connection of a device to the cable connection interface with the second ground path; enabling the first ground path based on determining the connection of the device; and disabling the second ground path based on determining the connection of the device. ### Claim 7 (depends on 6) The method of claim 6 wherein enabling the second ground path includes enabling the second ground path having a resistor coupled to the second switch in series. ### Claim 8 (depends on 6) The method of claim 6 further comprising monitoring the shield pin for a rate of voltage change using the second ground path. ### Claim 9 (depends on 6) The method of claim 6 wherein determining the connection of the device includes determining a voltage drop across a configuration channel pin caused by internal resistance within the device. ### Claim 10 (depends on 6) The method of claim 6 further comprising limiting peak voltage on the shield pin with a clamp. ### Claim 11 A shield fault detection system, comprising: a slope detector, the slope detector detects a rate of voltage change on a shield pin of a cable connection interface, the slope detector compares the rate of voltage change to a reference slope; a current sense circuit, the current sense circuit detects whether or not a current is flowing through a power pin of the cable connection interface; and a switch, the switch disconnects a ground path of the shield pin based on the rate of voltage change being above the reference slope and the current through the power pin not being detected, and the switch connects the ground path based on the rate of voltage change being above the reference slope and the current through the power pin being detected. ### Claim 12 (depends on 11) The system of claim 11 wherein the switch connects the ground path of the shield pin based on the rate of voltage change being below the reference slope. ### Claim 13 (depends on 11) The system of claim 11 wherein the slope detector compares the rate of voltage change to a linear reference slope. ### Claim 14 (depends on 11) The system of claim 11 wherein the slope detector detects the rate of voltage change on the shield pin of a type-A USB port, a type-B USB port, a type-C USB port, a mini USB port, a micro USB port, or a lightning connector. ### Claim 15 (depends on 11) The system of claim 11 further comprising a logic control module, the logic control module provides a signal to disconnect the switch between the shield pin and a ground. ### Claim 16 A weak ground path system, comprising: a first switch, the first switch disables a first ground path for a shield pin of a cable connection interface; a second switch, the second switch enables a second ground path for the shield pin, and the second ground path having a higher resistance than the first ground path; a comparator, the comparator determines a connection of a device to the cable connection interface with the second ground path; and a logic control module, the logic control module enables the first ground path based on a determination of the connection of the device, and the logic control module disables the second ground path based on the determination of the connection of the device. ### Claim 17 (depends on 16) The system of claim 16 wherein the second ground path includes a resistor coupled to the second switch in series. ### Claim 18 (depends on 16) The system of claim 16 further comprising a slope detector, the slope detector monitors the shield pin for a rate of voltage change using the second ground path. ### Claim 19 (depends on 16) The system of claim 16 wherein the comparator determines a voltage drop across a configuration channel pin caused by internal resistance within the device. ### Claim 20 (depends on 16) The system of claim 16 further comprising a clamp limiting peak voltage on the shield pin.