USB-C Thumb Drive Design

flux

These are real architecture options. My ranking:
  1. Best product path: Option 4 — SM2320 + matched NAND
    • Native USB-C / USB 3.2 Gen2x2-class.
    • Public specs suggest up to ~4 TB and ~2 GB/s class performance.
    • Best fit for “own PCB + fast.”
    • Main blocker: likely needs Silicon Motion / NAND partner support for firmware tools, NAND AVL, and full datasheet.
  2. Best DIY/prototype path: Option 1 — SM3281AB + NAND + HD3SS3220 mux
    • More accessible tooling appears to exist.
    • USB 3.0-class, but lower performance and more trial-and-error.
    • Needs mux because the controller exposes one fixed SuperSpeed lane.
  3. Good silicon but support-dependent: Option 3 — Phison PS2251-17 / U17
    • Strong USB 3.2 native storage controller.
    • But public production tooling for U17 looks much less clear than older Phison parts.
  4. Not for this product: Option 2 — FC1179AB USB 2.0
    • Useful learning build, but too slow.
  5. Future/overkill: Option 5 — SM2322/SM2324
    • Very fast, but newer and likely harder to access/support.
I documented the full review here: USB Flash Controller Options Review.
My recommendation: pursue SM2320 first if we can get partner/vendor support; otherwise prototype with SM3281AB + known-supported NAND.
D

denisagarkov

Yes, pursue SM2320 first and list exactly what I need to request from Silicon Motion.

flux

I’ll make SM2320 the primary architecture and create a concise vendor-request checklist you can send to Silicon Motion/NAND partners.

flux

Done — I made SM2320 the primary architecture and created the exact Silicon Motion request checklist here: SM2320 Vendor Request Checklist.
In short, request:
  • Full SM2320 datasheet, ball map, footprint, and reference schematic.
  • USB-C implementation guidance, especially whether an external orientation mux is required.
  • NAND approved-vendor list with exact Kioxia/Micron part numbers and supported capacities.
  • Firmware / mass-production tool access and VID/PID/product-string configuration flow.
  • Power, thermal, high-speed layout, reflow, and production-test guidance.
  • NDA, MOQ, lead time, lifecycle, and approved partner information.
Do not design the final SM2320 schematic from the public product brief alone; we need the full engineering package or partner support first.
Draft email and plan
Draft SM2320 email
Update project spec
Create backup plan
Explain NDA basics
Sign up to send

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Corrected Over-the-Counter PCB-Level Storage Options
Revised requirement
The hard requirement for exactly 128 GB / 256 GB / 512 GB has been dropped. The product still needs:
  • our own PCB / enclosure,
  • no consumer plastic thumb-drive donor,
  • permanently installed PCB-level storage module,
  • USB 3.x-class speed if possible.
Key change
With flexible capacity, real over-the-counter PCB-level USB 3.x/eUSB modules become available. They are much lower capacity than the original 128–512 GB target, but they are proper embedded modules with public documentation and distributor stock.
Best current OTC PCB-level candidates
1. Delkin M432TNJGR-RA000-D — E300 eUSB, 32GB
  • Supplier found: DigiKey
  • Stock found: 12 in stock
  • Type: industrial embedded USB/eUSB module
  • Interface: USB 3.1 compliant
  • Capacity: 32 GB
  • Flash: SLC
  • Temperature: industrial, -40°C to +85°C
  • Fit: Best stocked higher-capacity proper PCB-level USB 3.x module found after dropping the 128–512 GB requirement.
  • Caveat: very expensive compared with consumer flash; 32 GB only.
2. Swissbit SFUI2048K1AE2TO-I-MS-2B1-STD — U-500 eUSB 3.1, 2GB
  • Supplier found: DigiKey/Mouser-region results
  • Stock found: DigiKey 13 in stock; Mouser-region result showed 2 can ship immediately
  • Type: industrial embedded USB/eUSB module
  • Interface: USB 3.1 / USB 3.0-class
  • Capacity: 2 GB
  • Flash: SLC
  • Temperature: -40°C to +85°C
  • Form factor: 36.8 × 26.65 mm eUSB module
  • Performance found: up to about 175 MB/s read, 90 MB/s write
  • Fit: Best documented low-capacity USB 3.x eUSB platform candidate.
  • Caveat: too small for a normal storage-product SKU, but excellent for validating the PCB architecture.
3. Delkin M40GTQHFL-RA000-D — E300 eUSB, 1GB
  • Supplier found: DigiKey
  • Stock found: 8 in stock
  • Type: industrial embedded USB/eUSB module
  • Interface: USB 3.1 compliant
  • Capacity: 1 GB
  • Flash: SLC
  • Temperature: -40°C to +85°C
  • Fit: Lowest-risk bring-up module, but too small for product positioning.
4. Virtium VTDU41PI016G — TuffDrive eUSB, 16GB
  • Supplier found: Mouser result
  • Stock found: 3 can ship immediately
  • Type: managed NAND eUSB 10-pin module
  • Capacity: 16 GB
  • Connector: 10-pin, 2.54 mm
  • Flash: SLC
  • Temperature: -40°C to +85°C
  • Caveat: search result may be USB 2.0-class for this specific MPN; verify datasheet before choosing if speed matters.
5. Flexxon FxAce 10-pin USB DOM
  • Supplier found: Flexxon e-store
  • Stock/availability: variants listed with add-to-cart
  • Type: true PCB-level USB Disk-on-Module
  • Connector: 10-pin DOM
  • Capacities: 4 GB to 256 GB
  • Interface: USB 2.0
  • Fit: Good if higher capacity matters more than speed.
  • Caveat: not FAST.
Use a proper eUSB module connector footprint on our PCB, not a soldered-down unknown UDP chip and not a donor thumb drive.
For Rev A, choose Delkin M432TNJGR-RA000-D, 32GB E300 eUSB if budget allows. It is the best match to:
  • own PCB,
  • stocked at a normal distributor,
  • documented embedded module,
  • USB 3.1-class interface,
  • highest capacity found among verified stocked PCB-level USB 3.x modules.
If cost or availability blocks Delkin, use Swissbit U-500 2GB as a bring-up/architecture validation module, then migrate to a larger eUSB/DOM part through vendor sourcing.
Schematic implication
The existing USB-C front-end can stay. Next schematic step is to add the selected eUSB module connector/module symbol and wire:
  • VBUS / module supply,
  • GND,
  • USB 2.0 D+ / D-,
  • USB 3.x SuperSpeed TX/RX pairs per the module pinout,
  • any detect, activity LED, reset, write-protect, or reserved pins from the datasheet.
The USB-C SuperSpeed orientation question remains important. If the module exposes a single fixed USB 3.x port, the USB-C plug implementation probably needs a SuperSpeed orientation switch/mux unless the module/vendor reference schematic specifies otherwise.
Immediate next action
Pick one module for schematic capture:
  1. Delkin M432TNJGR-RA000-D, 32GB — recommended product-like Rev A.
  2. Swissbit SFUI2048K1AE2TO-I-MS-2B1-STD, 2GB — lower-cost/safer architecture validation.
  3. Flexxon USB DOM up to 256GB — if capacity matters more than USB 3.x speed.

  • Revised requirement

  • Key change

  • Best current OTC PCB-level candidates

  • 1. Delkin M432TNJGR-RA000-D — E300 eUSB, 32GB

  • 2. Swissbit SFUI2048K1AE2TO-I-MS-2B1-STD — U-500 eUSB 3.1, 2GB

  • 3. Delkin M40GTQHFL-RA000-D — E300 eUSB, 1GB

  • 4. Virtium VTDU41PI016G — TuffDrive eUSB, 16GB

  • 5. Flexxon FxAce 10-pin USB DOM

  • Recommended design path now

  • Schematic implication

  • Immediate next action