TECHNICAL GUIDE
A USB Type-A to Type-B cable has a different plug on each end because USB 2.0 made the shape carry the role: the flat Standard-A end goes to the host, the squarer Standard-B end goes to the device. You cannot plug the cable in backwards, so a host can never be wired to a host. Contact counts on this page are from the USB-IF specifications; KINGCONN figures are from the drawings published on the part pages.
Standard-A is the flat rectangular receptacle on a PC, hub or charger. USB 2.0 Standard-A has 4 contacts: VBUS, D-, D+ and GND. USB 3.2 Gen 1 Standard-A keeps the same outline and adds a row behind it for the SuperSpeed pairs, making 9 contacts — which is why a USB 3.0 port accepts a USB 2.0 plug. The added row is the reason USB 3.0 receptacles are usually moulded in blue, as on 7USB3-F0-2001.
KINGCONN publishes 5 USB 2.0 and 4 USB 3.0 board-mount Standard-A parts, in vertical SMT, right-angle DIP and dual-port versions. 7USB3-F0-0016 is published at 9 contacts.
Standard-B is the tall, near-square receptacle you find on printers, scanners, audio interfaces and lab instruments. It has 4 contacts in USB 2.0 and 9 in USB 3.2 Gen 1, where the housing grows a stepped extension for the added row — so a USB 3.0 Standard-B plug does not fit a USB 2.0 Standard-B socket, although the reverse works.
Standard-B is not part of the KINGCONN board-mount range. It is described here because "USB Type-A to Type-B" is what the cable is called, and because equipment that still uses it is exactly the equipment that also needs the Mini-B and Micro-B parts below.
Mini-B and Micro-B are 5-contact connectors: VBUS, D-, D+, ID and GND. The ID pin is what USB On-The-Go uses to decide which end acts as host. Micro-B replaced Mini-B because its latch sits in the plug rather than the receptacle, which moves the wear to the cable — the part the user can replace.
USB 3.0 Micro-B widens the shell and goes to 10 contacts; 7MCUB-F0-0017 is published at 10 contacts with a 5.75 mm mated height and 10,000 mating cycles. KINGCONN lists 5 Mini-B parts at 0.80 mm contact pitch and 8 Micro-B parts with profile heights from 0.75 mm.
The USB Type-C receptacle has 24 positions, arranged as mirrored halves so the plug works either way up. The mirroring is what costs the position count: the pairs, VBUS and GND all appear on each side, plus CC1 and CC2 for orientation detection and power delivery negotiation, and SBU1 and SBU2 for alternate modes.
Not every design needs all 24. KINGCONN publishes Type-C receptacles at 24, 16 and 14 positions: 7USB31-C0-1001 is a 24-position receptacle and 7USB31-F0-0026 a 16-position receptacle. The 16-position versions drop the SuperSpeed pairs and serve charge-and-USB-2.0 products at lower cost and with simpler routing. Contact pitches in the family are 0.50, 0.70 and 0.85 mm, and durability is published at 3,000 to 10,000 mating cycles.
Type-C for anything user-facing and new. Micro-B where you are servicing an installed base or shipping into a market with an existing cable. Standard-A when the board is the host. Mini-B when the product line has to stay pin-compatible with equipment already in the field — that is a supply question rather than a design preference, and it is covered in the discontinued-connector guide.
See the USB receptacle selection guide for the selection parameters, the Type-C selection guide for pin count and durability, or the I/O connector overview for the whole range. Send your interface and mount style to service@kingconn.com.tw.
Standards referenced: