USB-C is the default connector for almost every new electronic product, but adding it is not the same as soldering a receptacle to a board. A simple low-power device needs only a pair of 5.1 kilohm CC pull-down resistors, protection, and a charger to receive basic 5 V; anything that needs a higher voltage requires a dedicated Power Delivery controller that negotiates a profile with the source. Behind the small connector sit an identification protocol, a power negotiation, non-trivial mechanical requirements, and an optional certification process. Here is what each one actually demands.

Why USB-C Became the Default

Nearly every founder who arrives with a new electronic product asks the same question during specification: which connector goes on the housing. The answer is almost always USB-C. It is the dominant standard in consumer products, regulators in several major markets now mandate a common charging connector across broad categories of portable devices, and customers simply expect the cable already in their drawer to fit. Choosing anything else means explaining why.

What Happens When the Cable Is Plugged In

Unlike older connectors, where voltage was simply present on a pin, USB-C requires the two ends to identify each other before meaningful current flows. Identification happens over the CC lines. In the simplest case it is set by pull-down resistors — a device that only wants basic bus power gets 5 V with a pair of 5.1 kilohm resistors and nothing more.

If you need more than that, Power Delivery enters the picture: the product requests a voltage and current profile, the source advertises what it can supply, and the two converge. In practice that means a dedicated PD controller or a microcontroller running a PD stack — not just a receptacle.

  • Simple, low-current product: no PD needed. Resistors, protection, charger. Cheapest and most reliable path.
  • Product needing higher voltage or power: a PD controller to request 9 V, 15 V or 20 V. This also changes the downstream conversion chain, since your regulators now see a wide input range.
  • Product that also sources power outward: a dual role, and a substantially more complex design of protection and routing.

In every case the decision follows from the product's energy budget. If there is a battery involved, work through battery pack design first — the pack capacity and charge profile set the power requirement, not the other way round.

Charging: How Much Power Does the Product Really Need?

A frequent mistake is designing toward the maximum the standard permits rather than toward what the product consumes. Every step up in power adds components, heat, board area, and cost.

Ask first: what is the battery capacity, what charge time will the user accept, and does the product operate while charging? A wearable that charges overnight needs nothing beyond the basics. A power tool with a large pack that the user wants filled during a coffee break does.

Watch the thermal side too. Fast charging inside a sealed enclosure is a real thermal problem that needs dissipation area and often a firmware-imposed charge rate limit, especially in small products. In designs where the connector opening compromises sealing, wireless charging is sometimes the better trade — the sealing implications are covered in IP ratings explained.

Data Over the Same Connector

The great advantage of USB-C is that the same port carries data. Even if you never advertise the product as a data device, wire the data lines anyway. They give you a production configuration interface, a way to pull logs from a returned unit, and above all a firmware update path. A product you can revive and update over the cable saves expensive field returns and complements over-the-air updating rather than replacing it — see OTA firmware updates.

If you have chosen a microcontroller with an integrated USB peripheral, this is nearly free in parts and board area; see how to choose a microcontroller. Note that higher data rates require controlled-impedance differential pairs, which affects your stackup and layout — see PCB design and prototype cost.

The Mechanical Side, Where Products Break

The connector is the component the user touches most, which makes it failure point number one. A few rules worth enforcing in every design:

  • Real mechanical anchoring. Choose a receptacle with through-hole anchoring legs rather than surface pads alone, so a pull on the cable cannot peel the footprint off the board.
  • Alignment to the housing opening. A small mismatch between the opening and the board-mounted connector becomes a permanent side load. Define tolerances and build a check fixture.
  • Mating cycle rating. The datasheet specifies an insertion cycle count. Confirm it matches the expected usage frequency over the product's life.
  • Sealing. Any opening degrades the ingress rating, and gaskets around a connector are hard to do well.
  • Strain relief and drop behavior. A cable plugged in during a fall levers directly on the board — worth considering alongside drop test design.

Protection, Compliance, and Certification

Every exposed pin is an entry point for electrostatic discharge, so protection diodes on the data and power lines are mandatory rather than optional. Beyond that there are two separate regulatory layers, and they are often confused:

  • Product compliance. Electrical safety and electromagnetic compatibility, which are prerequisites for selling in your target market. For the US, that means the relevant safety standard for your product category and an emissions evaluation — see FCC certification for electronics and EMC testing cost.
  • USB specification compliance. A separate process, relevant mainly if you intend to use the official logo or sell through channels that require it.

Even if you never pursue formal USB certification, design to the specification anyway. A product that deviates behaves badly with certain chargers, and those complaints go straight into customer reviews.

Decide Early, Not Late

Choosing a connector sounds like a small decision, but it touches power topology, enclosure design, firmware, and certification — so make it during concept definition, not at the end. Validate it on real units through the build phases described in EVT, DVT and PVT, and see the rest of our electronics development articles for the surrounding decisions.

If you are specifying a new electronic product and want the connector, power path, firmware, and enclosure decisions made as one coherent design rather than in sequence, get in touch through our contact form.