Connectors
USB-C pinout
All 24 contacts of the USB Type-C receptacle and plug, what each one does, and how the connector negotiates power up to 240 W.
Receptacle (socket) front view - full-featured, 24 contacts
GroundDataPowerConfigurationSpecial
Tap or hover any pin to see what it does.
USB Type-C has 24 contacts in two rows of 12 on a centre tongue. The layout is symmetrical, so the plug fits either way up; the two configuration-channel pins (CC1 and CC2) tell each end which way round the cable is and what power it can carry. Four VBUS and four ground contacts share the current, and two pairs of high-speed lanes carry USB 3.x, USB4 or DisplayPort.
Tap any pin in the diagram to see its function. Switch between the receptacle (socket) view, the plug view (a mirror image) and the simplified USB 2.0-only connector found on many chargers and low-cost devices.
Receptacle (socket) front view: every pin
| Pin | Name | Function |
|---|---|---|
| A1 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| A2 | TX1+ | SuperSpeed / USB4 lane 1 transmit, positive halfHigh-speed differential pair with A3. Not used on USB 2.0-only ports. |
| A3 | TX1- | SuperSpeed / USB4 lane 1 transmit, negative halfPairs with A2. |
| A4 | VBUS | Bus power: 5 V default, up to 20 V (SPR) or 48 V (EPR) under a USB PD contractOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| A5 | CC1 | Configuration channel: attach and orientation detection; Current advertisement via Rp (source) / Rd (sink); USB Power Delivery messages (BMC-coded); Becomes the VCONN output when the cable's CC wire lands on CC2Each CC pin needs its own termination: a sink fits a separate 5.1 kΩ Rd to ground on CC1 and on CC2. |
| A6 | D+ | USB 2.0 data +, position 1Bridge to B6 on the board with a very short stub (spec guidance: under 3.5 mm) so USB 2.0 works with the plug either way up. |
| A7 | D- | USB 2.0 data -, position 1Bridge to B7 on the board. |
| A8 | SBU1 | Sideband use: Alternate Modes (for example DisplayPort AUX); USB4 sideband transmit (SBTX); Liquid detectionLeave open or with only a weak pull-down when unused. SBU1 at one end of a cable arrives on SBU2 at the other. |
| A9 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| A10 | RX2- | SuperSpeed / USB4 lane 2 receive, negative halfPairs with A11. |
| A11 | RX2+ | SuperSpeed / USB4 lane 2 receive, positive halfPairs with A10. |
| A12 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| B1 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| B2 | TX2+ | SuperSpeed / USB4 lane 2 transmit, positive halfPairs with B3. |
| B3 | TX2- | SuperSpeed / USB4 lane 2 transmit, negative halfPairs with B2. |
| B4 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| B5 | CC2 | Configuration channel (second position); Becomes the VCONN output when the cable's CC wire lands on CC1Mirror of A5 for the flipped orientation. Needs its own 5.1 kΩ Rd on a sink. |
| B6 | D+ | USB 2.0 data +, position 2Bridge to A6. |
| B7 | D- | USB 2.0 data -, position 2Bridge to A7. |
| B8 | SBU2 | Sideband use: Alternate Modes; USB4 sideband receive (SBRX)Leave open or weakly pulled down when unused. |
| B9 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| B10 | RX1- | SuperSpeed / USB4 lane 1 receive, negative halfPairs with B11. |
| B11 | RX1+ | SuperSpeed / USB4 lane 1 receive, positive halfPairs with B10. |
| B12 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
Plug front view: every pin
| Pin | Name | Function |
|---|---|---|
| A1 | GND | Ground / power returnAll four GND contacts are joined inside the plug and bonded to the shield/braid. |
| A2 | TX1+ | SuperSpeed / USB4 lane 1 transmit, positive halfPairs with A3. In a full-featured cable this contact is wired to B11 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| A3 | TX1- | SuperSpeed / USB4 lane 1 transmit, negative halfPairs with A2. In a full-featured cable this contact is wired to B10 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| A4 | VBUS | Bus power: 5 V default, up to 20 V (SPR) or 48 V (EPR) under a USB PD contractAll four VBUS contacts are joined inside the plug. Full-featured cables carry a 10 nF bypass capacitor on VBUS at each end (rated 30 V, or 63 V for EPR cables). |
| A5 | CC | The single configuration-channel wire of the cable; Carries attach detection, current advertisement and USB PD messagesOnly one CC conductor runs through a cable; it connects A5 to A5. A legacy C-to-A cable puts a 56 kΩ Rp here; a C-to-Micro-B/Standard-B cable puts a 5.1 kΩ Rd here. |
| A6 | D+ | USB 2.0 data +, position 1The cable's only USB 2.0 pair; runs straight through to the same position at the other end. |
| A7 | D- | USB 2.0 data -, position 1The cable's only USB 2.0 pair; runs straight through to the same position at the other end. |
| A8 | SBU1 | Sideband use: Alternate Modes (for example DisplayPort AUX); USB4 sideband transmit (SBTX); Liquid detectionWired to B8 at the other end of a full-featured cable. Absent in USB 2.0-only plugs. |
| A9 | VBUS | Bus powerAll four VBUS contacts are joined inside the plug. Full-featured cables carry a 10 nF bypass capacitor on VBUS at each end (rated 30 V, or 63 V for EPR cables). |
| A10 | RX2- | SuperSpeed / USB4 lane 2 receive, negative halfPairs with A11. In a full-featured cable this contact is wired to B3 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| A11 | RX2+ | SuperSpeed / USB4 lane 2 receive, positive halfPairs with A10. In a full-featured cable this contact is wired to B2 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| A12 | GND | Ground / power returnAll four GND contacts are joined inside the plug and bonded to the shield/braid. |
| B1 | GND | Ground / power returnAll four GND contacts are joined inside the plug and bonded to the shield/braid. |
| B2 | TX2+ | SuperSpeed / USB4 lane 2 transmit, positive halfPairs with B3. In a full-featured cable this contact is wired to A11 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| B3 | TX2- | SuperSpeed / USB4 lane 2 transmit, negative halfPairs with B2. In a full-featured cable this contact is wired to A10 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| B4 | VBUS | Bus powerAll four VBUS contacts are joined inside the plug. Full-featured cables carry a 10 nF bypass capacitor on VBUS at each end (rated 30 V, or 63 V for EPR cables). |
| B5 | VCONN | Plug power (3.0-5.5 V) for the e-marker chip or active electronics in the cableUsed in electronically marked cables. The receptacle's spare CC pin feeds it. Before VCONN is applied a powered cable shows Ra (800 Ω-1.2 kΩ) on this contact. |
| B6 | (none) | No contact here in a Type-C plug; a cable carries only one USB 2.0 pair (A6/A7). |
| B7 | (none) | No contact here in a Type-C plug; a cable carries only one USB 2.0 pair (A6/A7). |
| B8 | SBU2 | Sideband use: Alternate Modes; USB4 sideband receive (SBRX)Wired to A8 at the other end of a full-featured cable. Absent in USB 2.0-only plugs. |
| B9 | VBUS | Bus powerAll four VBUS contacts are joined inside the plug. Full-featured cables carry a 10 nF bypass capacitor on VBUS at each end (rated 30 V, or 63 V for EPR cables). |
| B10 | RX1- | SuperSpeed / USB4 lane 1 receive, negative halfPairs with B11. In a full-featured cable this contact is wired to A3 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| B11 | RX1+ | SuperSpeed / USB4 lane 1 receive, positive halfPairs with B10. In a full-featured cable this contact is wired to A2 at the far end, so each transmitter meets a receiver. Absent in USB 2.0-only plugs. |
| B12 | GND | Ground / power returnAll four GND contacts are joined inside the plug and bonded to the shield/braid. |
USB 2.0-only receptacle: every pin
| Pin | Name | Function |
|---|---|---|
| A1 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| A2 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| A3 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| A4 | VBUS | Bus power: 5 V default, up to 20 V (SPR) or 48 V (EPR) under a USB PD contractOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| A5 | CC1 | Configuration channel: attach and orientation detection; Current advertisement via Rp (source) / Rd (sink); USB Power Delivery messages (BMC-coded); Becomes the VCONN output when the cable's CC wire lands on CC2Each CC pin needs its own termination: a sink fits a separate 5.1 kΩ Rd to ground on CC1 and on CC2. |
| A6 | D+ | USB 2.0 data +, position 1Bridge to B6 on the board with a very short stub (spec guidance: under 3.5 mm) so USB 2.0 works with the plug either way up. |
| A7 | D- | USB 2.0 data -, position 1Bridge to B7 on the board. |
| A8 | SBU1 | Sideband use: Alternate Modes (for example DisplayPort AUX); USB4 sideband transmit (SBTX); Liquid detectionContact position exists but should be left unconnected unless a specific function needs it. |
| A9 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| A10 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| A11 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| A12 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| B1 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
| B2 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| B3 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| B4 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| B5 | CC2 | Configuration channel (second position); Becomes the VCONN output when the cable's CC wire lands on CC1Mirror of A5 for the flipped orientation. Needs its own 5.1 kΩ Rd on a sink. |
| B6 | D+ | USB 2.0 data +, position 2Bridge to A6. |
| B7 | D- | USB 2.0 data -, position 2Bridge to A7. |
| B8 | SBU2 | Sideband use: Alternate Modes; USB4 sideband receive (SBRX)Contact position exists but should be left unconnected unless a specific function needs it. |
| B9 | VBUS | Bus powerOne of four VBUS contacts (A4, A9, B4, B9), all bussed together. A Type-C source keeps VBUS switched off until it detects a sink on CC, then supplies 5 V (or a higher negotiated USB PD voltage). |
| B10 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| B11 | NC | SuperSpeed position not used on a USB 2.0 receptacle; must not be connected to anything. |
| B12 | GND | Ground / power returnOne of four ground contacts (A1, A12, B1, B12). All four are tied together on the board and inside the plug. Ground and VBUS contacts touch before the signal contacts when you plug in. |
Key facts
- 24 contacts in two rows of 12 on a centre tongue. The arrangement is rotationally symmetric, so the plug fits either way up and the electronics work out the orientation from the CC pins.
- Power: VBUS on A4, A9, B4, B9 and ground on A1, A12, B1, B12 - each group is bussed together. Ground and VBUS contacts mate before the data and CC contacts.
- Orientation and attach detection: a source pulls CC up through Rp, a sink pulls each CC pin down through its own Rd of 5.1 kΩ. The CC pin that sees Rd tells the source which way the plug is inserted.
- The value of the source's Rp advertises current. Pull-up to 4.75-5.5 V: 56 kΩ = default USB power, 22 kΩ = 1.5 A, 10 kΩ = 3.0 A. Pull-up to 3.3 V: 36 kΩ / 12 kΩ / 4.7 kΩ. As current sources: 80 µA / 180 µA / 330 µA.
- Legacy adapter cables: a Type-C plug on a cable whose other end is a USB-A plug (or a C-to-Micro-B receptacle adapter, or a captive cable to a host) must contain a 56 kΩ ±5 % Rp. A C plug on a cable going to a Standard-B or Micro-B device end contains a 5.1 kΩ Rd.
- A Type-C source must leave VBUS unpowered until a sink is attached. That is why a gadget with no Rd resistors gets no power from a C-to-C charger, even though it charges from an old USB-A charger (legacy chargers are exempt and always drive VBUS).
- Default USB power is 500 mA for USB 2.0 ports and 900 mA (single-lane) or 1,500 mA (dual-lane) for USB 3.x ports. USB Type-C Current adds 1.5 A and 3.0 A at 5 V. Battery Charging 1.2 ports give up to 1.5 A.
- Order of precedence for power: USB PD overrides Type-C Current, which overrides BC 1.2, which overrides plain USB 2.0/3.x default power.
- USB Power Delivery negotiates over the CC wire. Standard Power Range reaches 20 V × 5 A = 100 W. Extended Power Range (PD 3.1+) adds fixed 28 V, 36 V and 48 V levels for 140 W, 180 W and 240 W. The Type-C spec caps VBUS at 48 V nominal.
- The receptacle contacts are rated for 5 A, but ordinary C-to-C cables are rated 3 A. Only cables with an e-marker chip may carry 5 A, and 240 W (EPR) cables must be e-marked for 5 A and 50 V.
- VCONN: after attach, the receptacle's unused CC pin is switched to VCONN (3.0-5.5 V) to power the e-marker or active electronics in the cable plug. Ports with SuperSpeed must be able to supply at least 1 W (1.5 W for two-lane); others at least 100 mW.
- SBU1/SBU2 are sideband pins for Alternate Modes (e.g. DisplayPort AUX) and the USB4 sideband channel (SBTX/SBRX). They cross over inside the cable. Unused SBU pins stay open or weakly pulled down.
- A cable carries only one USB 2.0 pair (plug contacts A6/A7). The receptacle has two pairs (A6/A7 and B6/B7) so the device must join A6 to B6 and A7 to B7.
- A USB 2.0-only receptacle uses 16 positions: 4× VBUS, 4× GND, CC1, CC2, both D+/D- pairs, and the two SBU positions (left unconnected unless needed). The eight SuperSpeed positions are empty.
- Power-only parts: a power-only plug needs just nine contacts (A1, A4, A5, A9, A12, B1, B4, B9, B12); a power-only receptacle keeps D+/D- but shorts them together inside the connector instead of routing them to the board.
- Signal names in the specification: TXp1/TXn1 = TX1+/TX1-, RXp2/RXn2 = RX2+/RX2-, Dp1/Dn1 = D+/D- at position 1, and so on. The plug's B6/B7 positions are empty.
Sources
Pin assignments were checked against these references on 2026-10-14. The diagram is our own drawing.
- USB Type-C Cable and Connector Specification, Release 2.5 (March 2026), USB-IF / USB 3.0 Promoter Group
- USB-IF document library entry for the Type-C specification
- USB-IF - USB Charger (USB Power Delivery)
- Espressif ESP-IoT-Solution - USB Type-C Hardware Design Guide
Questions people ask
How many pins does USB-C have?
24: twelve on each side of the centre tongue (A1–A12 and B1–B12). USB 2.0-only devices use a subset of them.
What are the CC pins on USB-C?
CC1 and CC2 are the configuration channel. Pull-up and pull-down resistors on them show which way the plug is inserted and how much current the source offers; USB Power Delivery messages also travel over CC.
Why does my USB-C device not charge from a USB-C charger?
The device must present 5.1 kΩ pull-down resistors (Rd) on both CC pins. Some cheap devices omit them, so a compliant USB-C charger never turns on VBUS. A USB-A to USB-C cable works because it has its own pull-up resistor.
How much power can USB-C carry?
Up to 5 V at 3 A (15 W) without negotiation, 100 W (20 V at 5 A) with USB Power Delivery and a 5 A cable, and up to 240 W (48 V at 5 A) with USB PD 3.1 Extended Power Range.