USB-C Power Delivery for Makers: Powering Projects From Any Charger

USB-C Power Delivery (USB PD) turns a common phone charger into a programmable bench supply. A single cable can deliver 5V, 9V, 12V, 15V, 20V and up to 100W, and a small trigger IC or microcontroller negotiates the voltage you need. This guide covers how the protocol works, which hardware to choose, how to wire it, and how to read the negotiated voltage in firmware.

Quick Takeaways

• USB PD negotiates voltage over the CC1/CC2 pins. A passive cable and a bare connector only give you 5V.
• A PD trigger board (such as the CH224K or IP2721) requests 9V, 12V, 15V, or 20V with no firmware.
• A resistor pair of 5.1kΩ on CC1 and CC2 makes a USB-C port advertise itself as a legal 5V sink.
• Always add a TVS diode, a fuse, and bulk capacitance to protect your load.

How USB-C Power Delivery Works

Old USB ports gave you 5V at 500mA on a VBUS line. USB-C changed the physical connector. USB PD changed the electrical contract.

Two devices talk over the CC (Configuration Channel) wire. The source (charger) advertises what it can supply. The sink (your project) picks a profile. The charger then switches VBUS to the chosen voltage.

The Basic Handshake

1. The charger places a pull-up resistor, Rp, on CC.
2. Your sink places a pull-down resistor, Rd = 5.1kΩ, on CC.
3. The charger detects Rd and enables 5V on VBUS.
4. For higher voltages, the sink sends PD messages over CC (a BMC-encoded digital signal at 300kHz).
5. The source replies with its Source Capabilities list.
6. The sink sends a Request for one profile.
7. The source confirms with Accept and PS_RDY, then changes the voltage.

Steps 4 through 7 are the part you outsource to a PD trigger IC or a PD sink controller.

Standard Fixed Voltage Profiles

Voltages above 20V (28V, 36V, 48V) exist under PD 3.1 Extended Power Range (EPR). They require 5A e-marked cables and compatible chargers.

Pinout Configuration of a USB-C Connector

A full USB-C receptacle has 24 pins. Makers usually need only a few.

Cheap breakout boards often expose only VBUS, GND, CC1, CC2, D+, and D-. Check that your breakout includes the 5.1kΩ pull-downs. Many do not.

Option 1: Dumb 5V With Two Resistors

This is the simplest design and works with every compliant USB-C charger.

Wiring:

• Connect a 5.1kΩ resistor from CC1 to GND.
• Connect a second 5.1kΩ resistor from CC2 to GND.
• Connect VBUS to your 5V rail.

Without those resistors, a USB-C to USB-C cable from a compliant charger delivers 0V. This is the most common beginner failure. If your project is dead on a USB-C charger, check CC1 and CC2 first.

For USB-A to USB-C cables, the resistors are not required. The cable already includes a 56kΩ pull-up on CC.

Option 2: PD Trigger Boards (No Code)

A PD trigger board hardwires the negotiation. You set the target voltage with solder jumpers, DIP switches, or a resistor on a config pin.

CH224K Trigger Configuration

The CH224K selects its voltage using the CFG1, CFG2, and CFG3 pins.

Pin tables vary by board vendor. Always read the silkscreen and the datasheet for your exact module. The CH224K supports 5V, 9V, 12V, 15V, 20V, and some revisions support 28V with PPS.

Practical Rules for Trigger Boards

• Confirm the charger supports your voltage. A 5V/3A phone charger will not provide 12V.
• Check current rating of the trigger board’s traces and connector, not just the IC.
• Measure VBUS with a multimeter before connecting your load.
• If negotiation fails, most boards fall back to 5V.

Option 3: Programmable Sink With the STUSB4500

The STUSB4500 is a USB PD sink controller with non-volatile memory (NVM). You program up to three Power Data Objects (PDOs) over I2C, and it stores them permanently.

Key Specifications

Circuit Breakdown

1. VBUS from the connector feeds the VBUS_SENSE pin through a divider or direct tie, per datasheet.
2. CC1 and CC2 connect directly to the matching CC1DB/CC1 and CC2DB/CC2 pins.
3. VBUS_EN_SNK drives the gate of a P-channel MOSFET that gates power to your load.
4. Add a 100nF and a 10µF capacitor near VDD.
5. Connect SDA and SCL to your microcontroller with 4.7kΩ pull-ups to 3.3V.

The MOSFET matters. Your load stays disconnected until the PD contract completes, so a high-voltage mistake cannot reach your electronics.

Arduino Code: Read STUSB4500 Status

This sketch reads the RDO (Request Data Object) register to confirm which voltage and current were negotiated. It uses the standard Wire library on an ESP32 or Arduino with 3.3V logic.

#include <Wire.h>

// STUSB4500 default 7-bit I2C address
#define STUSB_ADDR   0x28
// Register holding the Request Data Object (RDO), 4 bytes
#define RDO_REG      0x91

void setup() {
  Serial.begin(115200);
  Wire.begin();            // SDA/SCL default pins
  Wire.setClock(400000);   // 400kHz fast mode supported by STUSB4500
  delay(500);              // Allow PD negotiation to complete
}

void loop() {
  uint32_t rdo = 0;

  Wire.beginTransmission(STUSB_ADDR);
  Wire.write(RDO_REG);     // Point to the RDO register
  Wire.endTransmission(false);
  Wire.requestFrom((uint8_t)STUSB_ADDR, (uint8_t)4);

  // Assemble 4 bytes, little-endian
  for (int i = 0; i < 4 && Wire.available(); i++) {
    rdo |= ((uint32_t)Wire.read()) << (8 * i);
  }

  // Bits 19:10 hold the operating current in 10mA units
  uint16_t current_mA = ((rdo >> 10) & 0x3FF) * 10;

  Serial.print("Operating current request: ");
  Serial.print(current_mA);
  Serial.println(" mA");

  delay(1000);
}

This reads the negotiated current. To read the active PDO voltage, read the PDO registers starting at 0x85 and decode bits 19:10 (voltage in 50mV units). Use the open-source STUSB4500 library from SparkFun for full NVM programming.

Option 4: Full Software PD With a Sink Controller

When you need PPS (Programmable Power Supply), which lets you request any voltage from 3.3V to 21V in 20mV steps, move to an advanced controller. The TPS25730, CYPD3177, and STUSB4500 (fixed profiles only) serve different needs.

Use PPS for battery chargers and bench supply builds. A PPS charger can adjust voltage dynamically, which suits CC/CV lithium charging.

Choosing the Right Charger

Not all chargers offer every profile. Look at the label.

• A label reading 5V/3A, 9V/3A, 12V/2.25A, 15V/3A, 20V/5A supports all fixed profiles.
• Chargers from GaN brands often include PPS.
• A phone charger marked 5V/2A only is not a PD charger.
• Laptop chargers are excellent sources: 65W and 100W units are cheap and widely available.

Use a certified e-marked cable for currents above 3A. An unmarked cable limits you to 3A, even if the charger supports 5A.

Protecting Your Circuit

PD chargers hot-plug at up to 20V. Hot-plugging a long cable onto a low-ESR capacitor creates a voltage spike that can reach double the supply voltage due to cable inductance. Protect against it.

For a 20V rail, select a TVS with a standoff voltage above 20V, such as the SMBJ22A or SMBJ24A. Use capacitors rated for at least 35V. Ceramic capacitors lose a significant part of their capacitance under DC bias, so check the DC-bias curve in the datasheet.

Step-Down: Getting 3.3V and 5V From 12V or 20V

Most microcontrollers need 3.3V or 5V. Add a buck converter after the PD stage.

An LDO from 20V to 3.3V at 200mA wastes (20 − 3.3) × 0.2 = 3.34W as heat. That melts a small package. Use a buck converter whenever the input-to-output drop is large.

Real-World Project: 12V LED Strip Controller With ESP32

This build powers a 12V LED strip and an ESP32 from a single USB-C PD charger.

Parts List

• CH224K PD trigger board (set to 12V)
• MP1584EN buck module (set to 5V)
• ESP32 DevKit
• IRLZ44N logic-level N-channel MOSFET
• 10kΩ pull-down resistor
• 220Ω gate resistor
• 12V LED strip (max 3A)
• SMBJ15A TVS diode

Wiring Steps

1. Plug the CH224K into a 30W or higher PD charger.
2. Verify 12V on the output with a multimeter.
3. Connect the SMBJ15A across the 12V rail and GND.
4. Feed 12V to the LED strip positive terminal.
5. Connect the LED strip negative to the MOSFET drain.
6. Connect the MOSFET source to GND.
7. Connect GPIO25 to the MOSFET gate through the 220Ω resistor.
8. Place the 10kΩ resistor from gate to GND.
9. Feed 12V into the MP1584EN, set it to 5V, and connect the output to the ESP32 VIN pin.
10. Tie all grounds together.

MicroPython Code: PWM Dimming

from machine import Pin, PWM
import time

# GPIO25 drives the MOSFET gate
led = PWM(Pin(25), freq=1000)   # 1kHz PWM avoids visible flicker

while True:
    # Ramp brightness up (duty range is 0-1023 on ESP32 MicroPython)
    for duty in range(0, 1024, 8):
        led.duty(duty)
        time.sleep_ms(10)
    # Ramp brightness down
    for duty in range(1023, -1, -8):
        led.duty(duty)
        time.sleep_ms(10)

The ESP32 GPIO outputs 3.3V. The IRLZ44N is a logic-level MOSFET with a gate threshold of 1V to 2V, so 3.3V drive switches it fully on.

Troubleshooting USB-C PD Builds

Measure VBUS at the connector, then at your load. A drop above 0.3V points to resistive losses in the cable or traces.

FAQ

Can I power an Arduino from a USB-C PD charger?

Yes. A USB-C PD charger supplies 5V by default to any sink with 5.1kΩ pull-downs on CC1 and CC2. Most Arduino Uno and Nano boards use USB-A, micro-USB, or mini-USB, so use a USB-C to USB-A adapter cable or an Arduino with a USB-C connector, such as the Nano ESP32. The Arduino’s own regulator accepts up to 20V on VIN on some boards, but check your specific board’s rating.

How do I get 12V from a USB-C charger?

Use a PD trigger board such as the CH224K or IP2721 configured for 12V. Plug it into a charger that lists 12V among its profiles. The board negotiates the voltage and outputs 12V on its terminals.

Does USB-C PD need a special cable?

For up to 3A (60W at 20V), any standard USB-C cable works. For 5A (100W at 20V), you need an e-marked cable. Charging at 5V needs no special cable.

Is USB-C PD safe for low-voltage electronics?

It is safe when your design is correct. The charger only raises the voltage after a successful negotiation, and defaults to 5V. Add a TVS diode, a fuse, and a buck converter so downstream 3.3V and 5V parts never see 20V.