When a device is connected to another using a cable-and-connector, e.g., a USB cable, an electrical transient can occur that can cause damage to the device or put it in an unknown state. This disclosure describes techniques to protect devices from such transient electrical spikes. The ground of the connector is coupled to the ground of the device via one of two paths, a high-impedance path or a low-impedance path. The connector-ground to device-ground coupling is mediated by a software-controlled switch, which defaults to the high-impedance path. When a cable is connected to the device, energy transfer between the connectors occurs via the high-impedance path, thereby forestalling device damage or errors. A short while after the connectors are plugged, the switch switches to the low-impedance path, which puts the device in a normally operative state.
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Lee, Benjamin and Wong, Warwick, "Suppressing Electrical Transients Using Smart Control of the Impedance to Ground", Technical Disclosure Commons, (November 18, 2021)