| US 11,751,790 B1 | ||
| Protective circuitry for external sensing applications | ||
| Priyank Dineshbhai Patel, San Jose, CA (US); and Nilay D. Jani, San Jose, CA (US) | ||
| Assigned to Apple Inc., Cupertino, CA (US) | ||
| Filed by Apple Inc., Cupertino, CA (US) | ||
| Filed on Aug. 26, 2019, as Appl. No. 16/551,704. | ||
| Claims priority of provisional application 62/844,106, filed on May 6, 2019. | ||
| Int. Cl. A61B 5/276 (2021.01); H03K 17/687 (2006.01); A61B 5/00 (2006.01); A61B 5/339 (2021.01) | ||
| CPC A61B 5/276 (2021.01) [A61B 5/339 (2021.01); A61B 5/681 (2013.01); A61B 5/6826 (2013.01); A61B 5/7221 (2013.01); H03K 17/687 (2013.01); A61B 2562/0209 (2013.01)] | 17 Claims |
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1. A device comprising:
an external electrode disposed on an external surface of the device; sensing circuitry configured to sense a physiological signal via one or more electrodes including the external electrode during a first mode of operation; a switching circuit coupled between the external electrode and a node at a voltage, the switching circuit configured to:
in the first mode of operation, provide a low-impedance path between the external electrode and the node; and
in a second mode of operation different from the first mode of operation, provide a high-impedance path between the external electrode and the node; wherein:
the external electrode is a ground electrode and the node is a system ground node;
the external electrode is a reference electrode and the voltage is different from a system ground voltage, or
the external electrode is a measurement electrode and the voltage is different from the system ground voltage.
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