USB Cheat Sheet (2022)

This organizes the confusing structure created by mixed generation names and marketing names for USB. The same spec gets called by multiple names like USB 3.0, 3.1, 3.2, Gen 1/2, and the 5Gbps, 10Gbps, 20Gbps, 40Gbps families are grouped so their relationships can be compared at a glance.

The generation-by-generation table includes signal speed, MiB/s conversion, required wire count, and cable length together. For example, USB 1.1 is 12 Mbps, USB 2.0 is 480 Mbps, and USB4 40Gbps is 40000 Mbps, and the actual usable speed differences are also shown.

In the USB Gen A x B notation, A is the generation and B is the lane count, and the effective bandwidth reflecting encoding overhead is explained as well.

• USB 3.2 Gen 1 x 1: 5000 Mbps, 8b/10b, effective 4000 Mbps
• USB 3.2 Gen 2 x 1: 10000 Mbps, 128b/132b, effective 9696 Mbps
• USB 4 Gen 3 x 2: total 40000 Mbps, effective 38787 Mbps

Cables and connectors support different lane structures depending on whether they have 4-wire, 8-wire, or 12-wire configurations. 4-wire has PWR, GND, D+, D-, 8-wire adds RX/TX pairs to that, and 12-wire includes RX1/RX2, TX1/TX2 as well. USB Type-C has enough pins to support two lane configurations, and CC1/CC2 and SBU1/SBU2 are used for power negotiation, Alt Mode, and DisplayPort auxiliary signals.

Power specs are also summarized together. USB 2.0 is 5V 500mA 2.5W, USB 3.0/3.1 is 5V 900mA 4.5W, and USB-C PD 3.1 EPR goes up to 48V 5A 240W. Looking at data specs and power specs together reveals that USB is not simply a general-purpose port, but a composite specification that handles both speed and power delivery at the same time.