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Thread: They get extremely hot just sitting

13 Discord messages from ℹ️ - Information/general/threads/they-get-extremely-hot-just-sitting.md.

Category: ℹ️ - Information Parent channel: #general Thread ID: 1504636264761266217

Messages: 13

message-1504647519102046379

2026-05-15T00:52:03.553+00:00 — Thomas Dexter (@tdextrous)

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message-1504647524227481611

2026-05-15T00:52:04.775+00:00 — Thomas Dexter (@tdextrous)

Content

Without knowing any additional details, this sounds like it could be latch up. Does your design have sufficient well taps and substrate taps throughout the layout? Or are these included in the standard cells?
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message-1504649261709787207

2026-05-15T00:58:59.023+00:00 — Tholin (@tholin)

Content

They are included with the standard cells

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message-1504654862422642779

2026-05-15T01:21:14.337+00:00 — namibj

Content

I guess the epoxy isn't transparent to thermal IR? You could otherwise maybe use a macro lens on a thermal camera to hunt for it
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message-1504860580391948419

2026-05-15T14:58:41.323+00:00 — namibj

Content

Well, my offer of trying to reproduce in Xyce if it happens static from POR or external reset/reset-release after POR, does still stand.
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message-1504861338818838628

2026-05-15T15:01:42.146+00:00 — Tholin (@tholin)

Content

I think its the DACs
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message-1504861431890313307

2026-05-15T15:02:04.336+00:00 — Tholin (@tholin)

Content

The resistors in the R2R are small, requiring a buf_12 cell to drive and I have 11 DACs on here
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message-1504861681707384985

2026-05-15T15:03:03.897+00:00 — Tholin (@tholin)

Content

But I thought I wired each design that uses a DAC to send all 0s into the DAC when held in reset, to reduce the static power consumption to near zero
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message-1504861832072925294

2026-05-15T15:03:39.747+00:00 — Tholin (@tholin)

Content

But after checking with a multimeter, at least 4 of the analog outputs generate a non-zero voltage in reset
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message-1504861897500131469

2026-05-15T15:03:55.346+00:00 — Tholin (@tholin)

Content

So, I messed that up
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message-1504863649532215436

2026-05-15T15:10:53.063+00:00 — namibj

Content

Ahhh.

I'd still offer to try on reproducing from GDS though.
I hope the rest of the chip is nicely held when in reset at least to not burden Xyce with changing things; I'd happily use your chip to learn how to get things like this working on layouts this large.
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message-1504864156623437824

2026-05-15T15:12:53.963+00:00 — namibj

Content

I just don't like the idea of rebuilding the GDS from the GitHub repo because I'd expect it to not be a reproducible build given you didn't even hash-pin the PDK in the makefile (it's tag-pinned).
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message-1504871952769089608

2026-05-15T15:43:52.709+00:00 — namibj

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Hey, at least the DACs aren't internally shorted to GND....
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