How bad can a $2.97 ADC be?

Decapping and Identifying Fake/Clone Chips

• Several commenters suggest physically comparing cheap vs. “legit” parts: sanding the package and inspecting the die under a (even USB) microscope.
• Others use harsher methods: boiling sulfuric/nitric acid or molten rosin to dissolve epoxy, or even SEM imaging.
• Laser ablation is mentioned but considered risky for damaging the die and producing toxic fumes.
• Sandpaper + simple optics is highlighted as a surprisingly effective, low‑tech approach.

Are the Cheap Parts Clones, Rejects, or Genuine?

• Possibilities debated: functional clones, relabeled lower‑spec parts, or out‑of‑tolerance rejects leaking from production.
• Some point out TI fabs most analog in‑house and typically bins or discards out‑of‑spec wafers rather than reselling.
• One theory: the cheap devices might be a clone like Analogy’s ADX111A, whose datasheet appears heavily copied from TI’s.
• Others suspect simple relabeling of a related TI part was likely but note the reported 16‑bit output contradicts some relabel theories.

Pricing, Distributors, and Grey‑Market Debate

• Large buyers and Chinese distributors reportedly pay far less than catalog prices at Western distributors; wafer costs for mature nodes can be very low.
• LCSC is defended by multiple users as a large, trustworthy source; others denounce it as grey‑market with dubious traceability.
• Some argue Digikey/Mouser markups reflect inventory risk and logistics; others think their margins are “insane.”
• BOM pressure in consumer hardware is emphasized: a $3 part can be among the most expensive on a low‑cost product.

Measurement Technique and ADC Performance

• Several commenters question the article’s test setup: board layout, power supply, grounding, and ambient noise can dominate ADC performance.
• Swapping chips between boards is suggested to separate PCB effects from chip quality; measuring current draw is also recommended.
• It’s noted that delta‑sigma converters internally oversample and decimate; using the device’s built‑in averaging is not “misusing” it.

MCU vs Standalone ADCs (and ESP32 Complaints)

• On‑chip MCU ADCs are seen as “good enough” (10–12 ENOB) if carefully designed with proper references and noise control, but rarely match high‑end standalones.
• Some data points: RP2350 around 9.2 ENOB, cheap CH32 parts worse, STM32H7 achieving ~13 ENOB at higher cost.
• ESP32 ADCs are called out as particularly poor and non‑linear; reasons given include mixed‑signal process tradeoffs and on‑chip digital noise.

ADC Architectures and High‑Speed Designs

• Multi‑slope ADCs are praised as the gold standard for precision DC, though largely confined to lab gear.
• Delta‑sigma is viewed as the practical winner in many precision applications; SAR is common for mid‑speed work.
• High‑speed systems (CERN, oscilloscopes) often interleave many SAR cores or use custom ADCs with modest ENOB but very high sample rates, plus complex analog front ends.

Ultra‑Cheap MCUs and Clone Ecosystem

• A long subthread catalogs microcontrollers costing a few cents, with tradeoffs like one‑time programmability or minimal peripherals.
• Some argue these “jellybean” MCUs (Padauk, Nyquest, Puya, WCH) are quite usable; others call some of them highly specialized or painful to develop for.
• Shenzhen markets reportedly sell clones openly; for some applications clones are preferred if documented, while “stealth” clones masquerading as brand‑name parts are considered toxic to OEMs.

Reactions to the Follow‑up and LCSC Mention

• A follow‑up post by the author (linked in the thread) is noted.
• One commenter criticizes the original article for strongly implying LCSC‑sourced parts were suspect without hard evidence, viewing this as an unfair smear based on assumption rather than data.