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Analog I/O and ESD

Analog pad selection, electrical behavior, ESD guidance, and CoB boundary.

This page owns analog pad selection, electrical I/O behavior, ESD guidance, and the boundary between analog I/O and CoB geometry.

Current summary

The project-template discussion names gf180mcu_fd_io__asig_5p0 as the analog pad cell. NUM_INPUT selects a digital input pad; it does not select an analog pad. Confirmed fact, 2025-10-24. (archive message; Discord)

In the cited 2025 explanation, digital pads were described as having ESD protection. The analog pad was described as having only HBM protection diodes and requiring added protection. Confirmed guidance, not an independent pad-cell audit. (archive message; Discord)

The latest captured quarter-slot answer says all 48 I/O pads may be changed to analog pads. It replaces the common reading that the two default analog pads are a hard process limit. This is captured search evidence; its canonical Discord URL was not captured. (archive message)

CoB boundary

Pad type may be electrically flexible, but CoB bond-pad coordinates are not. Leo Moser said the bonder expects fixed coordinates and precheck verifies them. Decision boundary captured 2026-08-13. Its canonical Discord URL was not captured. (archive message)

The CoB coordinate and golden-mask rules are on CoB Pad Frame and Precheck.

ESD open work

A 2026 I/O ESD thread discussed snapback and the need to evaluate protection for the actual analog interface. Treat this as engineering discussion, not a universal approved network. (archive message; Discord)

Sources

  • 1428607555948777503 — 2025-10-17T04:56:23.583Z — Leo Moser (mole99) — archive message; Discord — Digital and analog pad ESD statement.
  • 1431170870432239777 — 2025-10-24T06:42:05.380Z — Leo Moser (mole99) — archive message; Discord — Analog pad-cell selection.
  • 1534680256223645878 — 2026-08-05T21:51:26.064Z — Leo Moser (mole99) — archive message; Discord — I/O ESD discussion.
  • 1537441624102141982 — 2026-08-13T12:44:07.470Z — Leo Moser (mole99) — archive message — CoB coordinate rule; canonical Discord URL not captured.
  • 1537464422279282738 — 2026-08-13T14:14:42.979Z — Leo Moser (mole99) — archive message — 48 I/O pads may become analog pads; canonical Discord URL not captured.