> > This is what I'll be trying first... My primary concern is how to go > > about buffering/protecting the inputs; touch + static = fried CMOS! Remember that the ESD problem comes about when a your body ground is floating at a much higher potential then environmental earth ground, usually several tens of kilovolts, and then you touch a output pin connected to a chip which is grounded to something close to earth ground. The shunting of the several kilovolt potential difference generates enough current to fry a hole through the gate oxide of the chip. For a device worn on the body if you make sure that it is grounded to the body of its wearer then no potential difference will build up. ( Though this can be a lot more uncomfortable then it sounds ). > Modern CMOS designs generally include clamping diodes at all I/O pads to protect > against ESD. I've never zapped a PIC pin, for example. Not true. While the diode protection on the inputs of modern devices have greatly reduced the damage done to a chip by ESD discharge you are still damaging the chips. Usually this will be expressed through the hot carrier effect, and electron punch through permanently scaring the gate oxide. The I/O pins still work just less and less efficiently. Much like a slow blow fuse they can take a lot of "hits" before they finally stop working. Aaron Toney, Circus Systems (206) 297-9015 -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQENAzgXSfoAAAEH/1fturuvJ3xeYxPSn2A/+6uE/q/On2L/+M0Ny0GbH/YHu3L8 7qOp1RgoDnUqszfO5F0pnG1oBIxJ5b5XZNqVonADVvuybb+jb9KseuVvPTTuEFhT /n+ZyhDDGudNFxWP4K98txyyxfDrGKTRTbJGE1JAhMJfiZD7a3/89mYvwkSUNGHW Gr2/rwFcBrpCxo9Mm7OramtVTEbIgLRF/TI0Sc7l7KjYQmxR6W0GV/hkFRKdU92V VIZ3KU6jjsmnY0/xtwpivs5QcD4Od/H/Z7cjtvTCcZD6gxuclBRBumc+kqOoQrS+ EbYxIYCsqsMt+OT58RHGBTP97ViXduDWvd3jmjEABRG0IEFhcm9uIFAuIFRvbmV5 IDxqb2Vib3lAaGhoaC5vcmc+ =Udxb -----END PGP PUBLIC KEY BLOCK----- -- Subcription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" toWear-Hard Mailing List Archive (searchable): http://wearables.blu.org
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