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title: Analog I/O and ESD
slug: curated-analog-io
route: /analog-design/io-and-esd
section: reference
access: public
summary: Analog pad selection, electrical behavior, ESD guidance, and CoB boundary.
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md_url: /analog-design/io-and-esd.md
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last_updated: 2026-08-19
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# Analog I/O and ESD

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](/evidence/designing/project-template/threads/mole99-is-there-any-esd-protection-in#message-1431170870432239777); [Discord](https://discord.com/channels/1361349522684510449/1428484368317288482/1431170870432239777))

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](/evidence/designing/project-template/threads/mole99-is-there-any-esd-protection-in#message-1428607555948777503); [Discord](https://discord.com/channels/1361349522684510449/1428484368317288482/1428607555948777503))

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](/evidence/live-delta/designing/analog#message-1537464422279282738))

## 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](/evidence/live-delta/designing/analog#message-1537441624102141982))

The CoB coordinate and golden-mask rules are on [CoB Pad Frame and Precheck](/packaging-and-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](/evidence/designing/analog/threads/io-esd#message-1534680256223645878); [Discord](https://discord.com/channels/1361349522684510449/1534564700904226986/1534680256223645878))

## Related pages

- [Analog Design](/analog-design)
- [Analog Layout, Verification, and PEX](/analog-design/layout-verification-and-pex)
- [CoB Pad Frame and Precheck](/packaging-and-cob/pad-frame-and-precheck)
- [Process Options and Open Questions](/process-and-pdk/options-and-open-questions)

## Sources

- `1428607555948777503` — 2025-10-17T04:56:23.583Z — Leo Moser (mole99) — [archive message](/evidence/designing/project-template/threads/mole99-is-there-any-esd-protection-in#message-1428607555948777503); [Discord](https://discord.com/channels/1361349522684510449/1428484368317288482/1428607555948777503) — Digital and analog pad ESD statement.
- `1431170870432239777` — 2025-10-24T06:42:05.380Z — Leo Moser (mole99) — [archive message](/evidence/designing/project-template/threads/mole99-is-there-any-esd-protection-in#message-1431170870432239777); [Discord](https://discord.com/channels/1361349522684510449/1428484368317288482/1431170870432239777) — Analog pad-cell selection.
- `1534680256223645878` — 2026-08-05T21:51:26.064Z — Leo Moser (mole99) — [archive message](/evidence/designing/analog/threads/io-esd#message-1534680256223645878); [Discord](https://discord.com/channels/1361349522684510449/1534564700904226986/1534680256223645878) — I/O ESD discussion.
- `1537441624102141982` — 2026-08-13T12:44:07.470Z — Leo Moser (mole99) — [archive message](/evidence/live-delta/designing/analog#message-1537441624102141982) — CoB coordinate rule; canonical Discord URL not captured.
- `1537464422279282738` — 2026-08-13T14:14:42.979Z — Leo Moser (mole99) — [archive message](/evidence/live-delta/designing/analog#message-1537464422279282738) — 48 I/O pads may become analog pads; canonical Discord URL not captured.