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UPEEC

Tri-State and Open-Drain Outputs

Outputs that can disconnect from a line, allowing several devices to share a bus.

Intermediate
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  • Tri-state output: high, low or high-impedance (Hi-Z, disconnected). Only one device drives a shared bus at a time — used in memory data buses.
  • Open-drain / open-collector output: can only pull low or let go. Several devices can share a line safely (wired-AND), and a pull-up resistor provides the high level. Used by I2C, interrupt lines and for level translation.

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