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.
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Project Specification: Fast USB-C Soldered-Storage Thumb Drive
User Requirement
Build a USB-C thumb drive with permanently soldered storage and fast transfer speed. Target capacity options are 128 GB, 256 GB, or 512 GB.
Selected Direction
Use a managed solder-down USB 3.x flash module / UDP-style embedded USB flash module. The module contains the flash controller, NAND, firmware, ECC, wear leveling, and USB mass-storage logic internally. The Flux PCB becomes a USB-C carrier/front-end board with power protection, Type-C configuration, ESD protection, and controlled-impedance USB routing.
Why This Direction
Raw USB flash controllers with NAND support are usually NDA-controlled and require vendor firmware/configuration tools. USB-to-eMMC/UFS bridge ICs with public documentation were not found in the Flux library. A managed USB 3.x module is the most realistic path to meet soldered storage + high speed with a public design.
Candidate Vendor Leads
  • MCDTEK UDP/MUDP: USB 3.0/2.0 UDP/MUDP modules, 16 GB–512 GB; page confirms Type-C options but does not publish pinout/datasheet.
  • Supertechina Micro UDP USB3.0: industrial UDP USB 3.0 flash chips; claims 512 GB Micro UDP capability; no public pinout/datasheet found.
  • GOODRAM / Apacer industrial USB 3.x products: good performance/capacity references, but most public parts are connectorized USB drives, not solder-down modules.
  • Virtium/Viking/Swissbit eUSB: credible industrial embedded USB modules, but capacity is commonly limited to 128 GB or below and often connectorized.
Current Decision Gate
A specific managed USB 3.x flash module MPN and datasheet/pinout are required before schematic capture can be completed. The public search did not find a Flux-library-ready 128/256/512 GB solder-down USB 3.x module with full pinout.
Electrical Architecture
  • USB-C connector or plug
  • USB-C UFP/device CC configuration with independent 5.1 kΩ Rd resistors on CC1/CC2
  • VBUS overcurrent/ESD protection
  • USB 3.x SuperSpeed ESD protection near connector
  • Type-C SuperSpeed orientation handling, either:
    • choose a USB-C plug/pinout that fixes orientation for a captive thumb-drive device, or
    • use a USB 3.x orientation switch/mux such as FUSB340 if using a receptacle
  • Managed USB 3.x flash module connected to VBUS/GND, USB2 D+/D−, and USB3 TX/RX pairs according to its datasheet
  • 4-layer controlled-impedance PCB recommended
Speed Target
A practical “fast thumb drive” target is ~200–400 MB/s read and vendor-dependent write speed. Exact performance depends on the selected managed module and NAND type.
Superseded Architecture
The earlier USB 2.0 microSDXC design is superseded and should be removed from the schematic because it requires a card and is too slow.
Next Required Input
Select/provide a module MPN or vendor datasheet/pinout. Without this, the schematic can only be a front-end carrier template, not a complete manufacturable storage design.

  • User Requirement

  • Selected Direction

  • Why This Direction

  • Candidate Vendor Leads

  • Current Decision Gate

  • Electrical Architecture

  • Speed Target

  • Superseded Architecture

  • Next Required Input