USB Type-C Wiring Diagram: Full 24-Pin Pinout, CC Logic, and Power Delivery Explained
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A USB Type-C wiring diagram maps all 24 pins of the reversible connector, covering SuperSpeed pairs, CC1/CC2 configuration channels, SBU lines, power rails, and ground.
USB Type-C is a 24-pin reversible connector defined in the USB Type-C Cable and Connector Specification. Its symmetrical physical layout means the plug can be inserted in either orientation, but this requires duplicating signal pairs on both sides of the connector. Understanding the pinout is essential for anyone designing cables, active adapters, or custom PCB receptacles.
The 24 pins break down as follows. There are four ground pins (GND, pins A1, A12, B1, B12) and four VBUS power pins (A4, A9, B4, B9) providing the 5 V bus at up to 3 A in standard configurations, or up to 5 A with a suitably rated Electronically Marked Cable (eMark) and USB Power Delivery negotiation.
The two Configuration Channel pins, CC1 (A5) and CC2 (B5), are among the most important signals. CC pins serve multiple functions: they detect plug orientation (which CC pin is pulled down to GND by the cable), communicate cable capabilities (via the eMark chip in active cables), and carry the USB Power Delivery (USB PD) protocol using BIPHASE MARK CODING (BMC). Pull-up resistors on the host side (Rp) and pull-down resistors on the device side (Rd) define the default current advertisement without USB PD. A 56 kΩ pull-up to VBUS signals 900 mA (USB 3.2 default), 22 kΩ signals 1.5 A, and 10 kΩ signals 3 A.
High-speed SuperSpeed data is carried on two differential pairs per side: TX1+/TX1− (A2/A3), RX1+/RX1− (B10/B11) on the primary side and TX2+/TX2− (B2/B3), RX2+/RX2− (A10/A11) on the secondary side. These pairs carry USB 3.2 Gen 1 (5 Gbps), Gen 2 (10 Gbps), or Gen 2×2 (20 Gbps) data. Legacy USB 2.0 is carried on D+/D− (A6, A7 and B6, B7), also duplicated for reversibility.
The SBU1 (A8) and SBU2 (B8) pins are Sideband Use pins reserved for alternate modes such as DisplayPort, Thunderbolt, and audio adapters. Their function depends entirely on the negotiated alternate mode and they carry no standard USB signal in USB-only operation.
Non-compliant DIY cables that connect CC1 or CC2 directly to VBUS can damage USB PD-capable devices by triggering uncontrolled high-voltage negotiation. Any cable connecting CC pins must use appropriate pull resistors — never a direct short to VBUS.
How to wire usb type c wiring diagram
- Identify the receptacle pinout orientation USB Type-C receptacles follow IEC 62680-1-3. Pin A1 is at top-left when the receptacle tongue is facing you. Pins A1–A12 run left to right on the upper row; pins B12–B1 run right to left on the lower row (mirrored). Obtain the mechanical drawing from your connector manufacturer to confirm pin 1 location before soldering.
- Wire VBUS and GND pins Connect all four VBUS pins (A4, A9, B4, B9) together to your power rail. Connect all four GND pins (A1, A12, B1, B12) together to circuit ground. Use adequate trace width or wire gauge: for 3 A continuous, use a minimum of 26 AWG wire per VBUS pair (two pairs paralleled provides headroom). For 5 A, use 24 AWG minimum per pair.
- Terminate the CC pins correctly For a UFP (device/sink): place a 5.1 kΩ ±5% resistor from CC1 (A5) to GND and a second 5.1 kΩ resistor from CC2 (B5) to GND. For a DFP (host/source): place Rp resistors from CC1 and CC2 to VBUS according to the current advertisement level. If using a USB PD controller IC, follow the IC datasheet — the IC handles CC termination internally.
- Wire SuperSpeed differential pairs Each SuperSpeed pair must be routed as a 90 Ω differential impedance controlled pair (for USB 3.x). On the primary side connect TX1+/TX1− (A2/A3) and RX1+/RX1− (B10/B11). On the secondary side connect TX2+/TX2− (B2/B3) and RX2+/RX2− (A10/A11). Maintain pair-to-pair length matching within 5 mil and minimise stub lengths.
- Wire USB 2.0 D+ and D− lines D+ is on A6 and B6; D− is on A7 and B7. In a device receptacle, connect A6 to B6 (joined D+) and A7 to B7 (joined D−), then route as a 90 Ω differential pair to your USB 2.0 controller. Series termination resistors of 22–33 Ω near the driver output are standard practice.
- Handle SBU pins for alternate mode or leave open SBU1 (A8) and SBU2 (B8) are used by DisplayPort Alt Mode (as ML3 and ML0 sideband), audio adapter mode, and Thunderbolt. If your design does not implement an alternate mode, leave SBU pins unconnected. If implementing DisplayPort Alt Mode, follow the VESA DisplayPort Alt Mode on USB Type-C Standard for mux configuration and SBU signal routing.
- Verify with USB compliance test equipment before production Use a USB Type-C protocol analyser to verify CC communication, plug orientation switching, and PD negotiation. Verify eye diagrams on SuperSpeed pairs using a USB compliance test fixture. Check that VBUS is not present before CC negotiation completes (VBUS must follow CC, not precede it, per the USB Type-C specification).
Specifications
| Total Pin Count | 24 (12 per side, mirrored for reversibility) |
|---|---|
| VBUS Pins | 4 (A4, A9, B4, B9) |
| GND Pins | 4 (A1, A12, B1, B12) |
| SuperSpeed Differential Pairs | 4 pairs (TX1, RX1, TX2, RX2) — 90 Ω differential impedance |
| USB 2.0 D+/D− Pairs | 2 (A6/A7 and B6/B7, shorted together at receptacle) — 90 Ω differential impedance |
| CC Pins | 2 (CC1: A5, CC2: B5) — carry PD BMC signalling and orientation detection |
| SBU Pins | 2 (SBU1: A8, SBU2: B8) — alternate mode sideband signals |
| Standard Power Range Maximum (USB PD 3.1 SPR) | 20 V / 5 A = 100 W (requires eMark cable rated ≥5 A) |
| Extended Power Range Maximum (USB PD 3.1 EPR) | 48 V / 5 A = 240 W (requires EPR-capable host, cable, and device) |
Safety warnings
- USB Power Delivery at Extended Power Range (EPR) voltages (up to 48 V) presents a shock hazard and can cause serious burns or fire if cables or connectors are damaged. Only use cables and connectors rated and certified for the negotiated voltage and current. Never modify or internally rewire certified USB PD cables.
- Incorrect CC pin wiring — particularly connecting CC to VBUS directly — can force USB PD-capable devices into uncontrolled high-voltage states, permanently damaging connected equipment. Always use the correct termination resistors as specified in the USB Type-C specification.
- VBUS must not be present on the bus before the CC handshake is complete. Designs that apply VBUS before CC negotiation violates the USB Type-C specification and can damage compliant UFP devices that have not yet configured their internal power management.
- Any PCB design or cable assembly intended for commercial sale must pass applicable regulatory testing (FCC Part 15, CE marking, TUV, UL) and USB-IF compliance testing. Self-built cables and boards should be treated as prototype/reference designs only and not used with equipment where failure could cause injury or data loss.
- High-speed differential pair routing requires controlled impedance PCB stackup. Incorrect impedance causes signal reflections, data errors, and potential EMI emissions that may violate regulatory limits.
Tools needed
- Digital multimeter with resistance and diode test functions
- Hot-air rework station or reflow oven (for SMT receptacle soldering)
- USB Type-C protocol analyser (for verifying CC negotiation and PD messaging)
- Oscilloscope with differential probes, minimum 2 GHz bandwidth (for SuperSpeed signal verification)
- USB compliance test fixture (for pre-compliance eye diagram measurement)
- Controlled impedance PCB fabrication (not a bench tool — a fabrication requirement for SuperSpeed designs)
- ESD wrist strap and grounded mat (USB receptacle pins are ESD-sensitive before ESD protection is installed)
Common mistakes
- Connecting only one VBUS pin and one GND pin — all four VBUS pins and all four GND pins must be connected to carry rated current without excessive resistance or heat.
- Omitting CC pull-down resistors on a device-side design — without Rd on both CC1 and CC2, the host will not detect the device and will not enable VBUS.
- Routing SuperSpeed differential pairs as single-ended traces or violating impedance control — USB 3.x pairs require 90 Ω differential impedance; an incorrect stackup causes bit errors even at short cable lengths.
- Using a USB Type-C connector footprint without its required mounting and shielding tabs connected to chassis ground — the shield tabs must be connected to chassis/earth ground, not signal ground, to prevent EMI and to provide mechanical robustness.
- Assuming a USB Type-C cable supports SuperSpeed because it has a Type-C connector on both ends — the cable must be specifically rated for USB 3.x or USB4; a charge-only or USB 2.0 cable with Type-C connectors does not contain SuperSpeed conductors.
Troubleshooting
- Host does not detect device or no VBUS appears after plug insertion
- Cause: Missing or incorrect CC termination resistors on device side (Rd), or CC pins not connected in cable Fix: Measure resistance from CC1 to GND and CC2 to GND at the device receptacle. Should read 5.1 kΩ each for a UFP. Verify cable has CC conductor connected (test with a known-good cable). Verify host Rp pull-up resistors are present.
- Device only detected in one plug orientation
- Cause: One of the two CC pins not connected or CC mux in the device not functioning Fix: Verify both CC1 (A5) and CC2 (B5) have their 5.1 kΩ Rd resistors populated. On UFP devices, the USB PD or CC detection IC reads which CC pin is pulled high by the host to determine orientation. Check IC power supply and firmware orientation detection logic.
- USB 2.0 enumeration works but USB 3.x SuperSpeed fails
- Cause: SuperSpeed differential pair routing errors, impedance mismatch, or inadequate cable/connector SuperSpeed rating Fix: Verify SuperSpeed pairs are connected to the correct pins (TX1/RX1 and TX2/RX2). Check PCB trace impedance — should be 90 Ω differential. Swap with a certified USB 3.x cable. Measure eye diagram on SuperSpeed pairs with oscilloscope and compare to USB specification mask.
- Power Delivery negotiation fails; device charges at only 5 V / 900 mA
- Cause: PD controller IC not communicating on CC, cable not eMark-rated, or host not PD-capable Fix: Monitor CC1/CC2 with an oscilloscope or USB PD protocol analyser during plug insertion. Verify BMC modulated PD messages are present. Confirm cable is rated for the required current (eMark required above 3 A). Verify PD controller firmware and CC resistors match IC datasheet requirements.
Frequently asked questions
Why does USB Type-C have two CC pins and when are both used?
CC1 and CC2 together enable plug-orientation detection. In a standard cable, only one CC pin is connected end-to-end; the other is used for Ra (cable pull-down for active cables) or the eMark chip communication. In a full-featured cable, both CC1 and CC2 are connected through the eMark chip, which identifies cable current capacity and supported alternate modes to the host controller.
What is the difference between a USB Type-C cable and a USB Type-C full-featured cable?
A standard (passive) USB Type-C cable carries USB 2.0 D+/D− and one CC pin, with SuperSpeed pairs optional depending on the rated USB generation. A full-featured cable carries all SuperSpeed pairs, both CC pins through an eMark chip, SBU lines, and VBUS/GND at full 5 A capacity. Full-featured cables are required for USB 3.2 Gen 2×2, USB4, and Thunderbolt 4 operation.
What resistors do I need on the CC pins when building a USB Type-C device?
A USB host (DFP — Downstream Facing Port) places a pull-up resistor (Rp) from CC1 and CC2 to VBUS: 56 kΩ for 900 mA, 22 kΩ for 1.5 A, or 10 kΩ for 3 A advertisement. A USB device (UFP — Upstream Facing Port) places a 5.1 kΩ pull-down resistor (Rd) from CC1 and CC2 to GND. USB PD controllers handle CC communication on top of these resistors.
Can I simply connect USB 2.0 D+ and D− wires inside a USB Type-C connector without the SuperSpeed pairs?
Yes. A charge-only or USB 2.0-only cable carries only VBUS, GND, CC (with the appropriate Ra or Rd termination), and D+/D−. The SuperSpeed pairs and SBU pins are unused. However, such a cable must still have CC correctly terminated or it will not be recognised as a compliant USB Type-C cable by host controllers that enumerate cable capability before enabling VBUS.
What voltage can USB Type-C Power Delivery supply, and what limits it?
USB PD 3.1 defines Standard Power Range (SPR) profiles up to 20 V / 5 A (100 W) and Extended Power Range (EPR) profiles at 28 V, 36 V, and 48 V up to 5 A (240 W maximum). The actual voltage and current negotiated depend on the source capability, cable rating (eMark chip data), and sink request. The cable must be Electronically Marked and rated for the negotiated current.
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