FIELD GUIDESource-led reference
Port & Cable

P069 / Storage / Standard

UHS-I and UHS-II bus interfaces

The SD Association lists UHS-I SDR104 at 104 MB/s and UHS-II at 156 MB/s full duplex or 312 MB/s half duplex. These bus figures are not guaranteed sustained card-write rates.

Also called UHS I UHS II UHS-I vs UHS-II

A bus ceiling is not a card benchmark.

The useful distinction

Read the bus mark separately from U1, U3 or V-class markings. A similar-looking numeral can refer to a different concept.

Claim inspection dates: 2026-10-01, 2026-10-07 · Independent review pending

Standard note · not an individual product specification

The useful distinction

Understand the requirement.

The SD Association lists UHS-I SDR104 at 104 MB/s and UHS-II at 156 MB/s full duplex or 312 MB/s half duplex. These bus figures are not guaranteed sustained card-write rates. [C069A]

UHS-I and UHS-II name bus interfaces; U1/U3 and V6/V10/V30/V60/V90 belong to speed-class symbol families. The SDA warns that matching numerical write-speed minima across different symbol families does not establish the host/card class match. [C069B]

Bounded facts, visible unknowns

Specifications and limits

UHS-I and UHS-II bus interfaces facts and limitations
UHS-I exampleSDR104: 104 MB/s bus rate [C069A]
UHS-II modes156 MB/s full duplex; 312 MB/s half duplex [C069A]
Observed speedDepends on the implementation and workload [C069A]
Verified device listNot included. Check exact device and accessory documentation.
A boundary, not an omission to guess around.

No speed measurement, general backward-compatibility guarantee or SKU recommendation is made.

Before you connect

What to check

  1. Identify the host bus support and exact mode.
  2. Check the selected card bus interface.
  3. Keep the required speed-class symbol as a separate requirement.
  4. Use measured or documented device behavior for transfer-time planning.
Trace a supported connection class →

Estimate transparently

The transfer worksheet allows a clearly labeled assumed usable fraction. It cannot discover a card benchmark or a reader bottleneck on its own.

Your next step

Move from the form to the requirement.

Compare this field note See the differences without assuming interchangeability.Work through a connection Choose your task before deciding on a cable.Explore this evidence trail Inspect the claims and their dependencies. (private workspace)

The source trail

Evidence for this page

AI-assisted inspection is not independent engineering review. Source scope and access limitations are disclosed below. Procedural checklists are editorial requirements, not hardware measurements.

C069ASource checked · pending review

The SD Association lists UHS-I SDR104 at 104 MB/s and UHS-II at 156 MB/s full duplex or 312 MB/s half duplex. These bus figures are not guaranteed sustained card-write rates.

SD Association · Bus Speed: Default, High Speed, UHS and SD Express ↗

Locator: Bus interface table; duplex explanation; final speed caveat
Access: public page. Specified bus modes and distinction from measured card performance.

S043: full source recordInspect review dependencies → (private workspace)

Claim scope: Named standard or manufacturer description only; procedural checks are editorial recommendations, not hardware tests.. Next review due 2026-12-30.

C069BSource checked · pending review

UHS-I and UHS-II name bus interfaces; U1/U3 and V6/V10/V30/V60/V90 belong to speed-class symbol families. The SDA warns that matching numerical write-speed minima across different symbol families does not establish the host/card class match.

SD Association · Bus Speed: Default, High Speed, UHS and SD Express ↗

Locator: Bus interface table; duplex explanation; final speed caveat
Access: public page. Specified bus modes and distinction from measured card performance.

S043: full source recordSD Association · SD Speed Class ↗

Locator: Speed-class families and Best Combination between Speed Class Host and Card
Access: public page. Bus modes and performance classes are distinct. Shared numeric minima across different class symbols do not guarantee the requested host class; no particular video mode is approved.

S044: full source recordInspect review dependencies → (private workspace)

Claim scope: Label interpretation and defined minimum sequential-performance conditions only; not a measured transfer rate, blanket recording-mode recommendation or certification of an individual card.. Next review due 2027-01-05.

Suggest a correction to this field note →

Common questions

Questions this record can help resolve

How many contacts do SD and microSD cards have?Identify the conventional first row without assuming every SD generation has the same contact count.SDHC, SDXC, UHS-I, U3 and V30: which label answers which question?Separate card shape, capacity family, bus interface and recording class instead of comparing unlike labels.Do microSD Express and microSD UHS-II use the same extra contacts?Two cards can share the microSD outline without sharing their second-row geometry or host interface.

Evidence behind this page

Scope first. Source second. Approval separate.

2 linked sources · 2 scoped claims · 0 sources with inspection/access flags.

Page scope: consumer_pilot

Assessment 2026-10-22 · earliest scheduled source review 2026-12-30. This is a recorded-date assessment, not a live source check. Page-level independent review is not established by this panel.

Inspect 2 source scopes, access limits and dates

S043 · Bus Speed: Default, High Speed, UHS and SD Express

SD Association · Standards-organization domain · inspected 2026-10-01 · due 2026-12-30

Within inspection window

Scoped support: Specified bus modes and distinction from measured card performance.

Not established / limitations: Specified bus modes and distinction from measured card performance.

Locator: Bus interface table; duplex explanation; final speed caveat

S044 · SD Speed Class

SD Association · Standards-organization domain · inspected 2026-10-07 · due 2027-01-05

Within inspection window

Scoped support: Minimum sequential-performance class symbols and same-family host/card matching under defined conditions.

Not established / limitations: Bus modes and performance classes are distinct. Shared numeric minima across different class symbols do not guarantee the requested host class; no particular video mode is approved.

Locator: Speed-class families and Best Combination between Speed Class Host and Card

Trace 2 claims to their source records

C069A · P069

The SD Association lists UHS-I SDR104 at 104 MB/s and UHS-II at 156 MB/s full duplex or 312 MB/s half duplex. These bus figures are not guaranteed sustained card-write rates.

Claim scope: Named standard or manufacturer description only; procedural checks are editorial recommendations, not hardware tests.

Source links: S043 · Evidence trail → (private workspace)

C069B · P069

UHS-I and UHS-II name bus interfaces; U1/U3 and V6/V10/V30/V60/V90 belong to speed-class symbol families. The SDA warns that matching numerical write-speed minima across different symbol families does not establish the host/card class match.

Claim scope: Label interpretation and defined minimum sequential-performance conditions only; not a measured transfer rate, blanket recording-mode recommendation or certification of an individual card.

Source links: S043 · S044 · Evidence trail → (private workspace)

Prepare this page for review → (private workspace)Read the evidence method →

Recorded evidence only. An inspection date, publisher label, source link or generated packet is not independent technical review, hardware testing, fabrication approval or a compatibility verdict.