Building a USB Power Delivery Trigger HAT

Overview

This tutorial designs a USB-C Power Delivery trigger HAT. The board uses a USB-C receptacle and a PD trigger controller such as the CH224K, FP28XX, or PD2001 to request a fixed voltage from a USB-C charger. The negotiated rail is filtered and exposed on a terminal block for external loads.

Use this HAT when a project needs a convenient 9 V, 12 V, 15 V, or 20 V rail from a USB-C charger. Do not connect the negotiated high-voltage rail directly to Raspberry Pi 5 V pins. The terminal block output is for external loads or a separate regulator stage.

Requirements

• USB-C receptacle with VBUS, GND, CC1, and CC2 connected to the PD controller.
• USB PD trigger/controller such as CH224K, FP28XX, or PD2001.
• Voltage-selection pins or resistors for 5 V, 9 V, 12 V, 15 V, or 20 V negotiation.
• Terminal block output for the negotiated rail.
• Status LED with current-limiting resistor.
• Input and output filtering capacitors.
• Wide VBUS/output copper and clear voltage silkscreen.

Voltage negotiation plan

PD trigger chips differ in their exact pin names, but the design pattern is the same:

Target output	Controller config example	Use case
5 V	default/no high-voltage request	logic rails and low-power loads
9 V	select pin mode for 9 V	small motors, LEDs, regulators
12 V	select pin mode for 12 V	fans, relays, buck regulators
15 V	select pin mode for 15 V	higher-power regulators
20 V	select pin mode for 20 V	only when the downstream circuit is rated for it

Always check the datasheet for your exact controller. The schematic below labels the selection pins generically as CFG1 and CFG2 so you can map them to the exact resistor strap table for CH224K, FP28XX, or PD2001.

Step 1: Add the HAT board

import { RaspberryPiHatBoard } from "@tscircuit/common"

export default () => (
  <RaspberryPiHatBoard name="HAT1">
    {/* USB PD trigger circuit goes here */}
  </RaspberryPiHatBoard>
)

Step 2: Add USB-C and PD controller parts

<chip name="J1" footprint="usb_c_receptacle" manufacturerPartNumber="USB-C receptacle" pinLabels={{ 1: "VBUS", 2: "GND", 3: "CC1", 4: "CC2" }} />
<chip name="U1" footprint="sop10" manufacturerPartNumber="CH224K USB PD trigger" pinLabels={{ 1: "VBUS", 2: "GND", 3: "CC1", 4: "CC2", 5: "CFG1", 6: "CFG2", 7: "PG", 8: "VOUT" }} />

Step 3: Add configuration, status, and output filtering

<resistor name="R1" resistance="10k" footprint="0402" />
<resistor name="R2" resistance="10k" footprint="0402" />
<resistor name="RLED" resistance="2.2k" footprint="0402" />
<led name="LED1" footprint="0603" color="green" />
<capacitor name="CIN" capacitance="10uF" footprint="0603" />
<capacitor name="COUT" capacitance="47uF" footprint="cap_0603" />
<chip name="J2" footprint="terminalblock_2" manufacturerPartNumber="PD output" pinLabels={{ 1: "VOUT", 2: "GND" }} />

Schematic and 3D preview

import { RaspberryPiHatBoard } from "@tscircuit/common"

export default () => (
<RaspberryPiHatBoard name="HAT1">
  <chip name="J1" footprint="usb_c_receptacle" manufacturerPartNumber="USB-C receptacle" pcbX={-24} pcbY={0} pinLabels={{ 1: "VBUS", 2: "GND", 3: "CC1", 4: "CC2" }} />
  <chip name="U1" footprint="sop10" manufacturerPartNumber="CH224K USB PD trigger" pcbX={-6} pcbY={0} pinLabels={{ 1: "VBUS", 2: "GND", 3: "CC1", 4: "CC2", 5: "CFG1", 6: "CFG2", 7: "PG", 8: "VOUT" }} />
  <chip name="J2" footprint="terminalblock_2" manufacturerPartNumber="PD output" pcbX={24} pcbY={0} pinLabels={{ 1: "VOUT", 2: "GND" }} />
  <resistor name="R1" resistance="10k" footprint="0402" pcbX={0} pcbY={8} />
  <resistor name="R2" resistance="10k" footprint="0402" pcbX={5} pcbY={8} />
  <resistor name="RLED" resistance="2.2k" footprint="0402" pcbX={12} pcbY={8} />
  <led name="LED1" footprint="0603" color="green" pcbX={17} pcbY={8} />
  <capacitor name="CIN" capacitance="10uF" footprint="0603" pcbX={-15} pcbY={8} />
  <capacitor name="COUT" capacitance="47uF" footprint="cap_0603" pcbX={15} pcbY={-8} />

  <trace from=".J1 > .VBUS" to="net.VBUS" />
  <trace from=".J1 > .GND" to="net.GND" />
  <trace from=".J1 > .CC1" to=".U1 > .CC1" />
  <trace from=".J1 > .CC2" to=".U1 > .CC2" />
  <trace from="net.VBUS" to=".U1 > .VBUS" />
  <trace from=".U1 > .GND" to="net.GND" />

  <trace from=".R1 > .pin1" to=".U1 > .CFG1" />
  <trace from=".R1 > .pin2" to="net.GND" />
  <trace from=".R2 > .pin1" to=".U1 > .CFG2" />
  <trace from=".R2 > .pin2" to="net.VBUS" />

  <trace from=".U1 > .VOUT" to="net.PD_OUT" />
  <trace from="net.PD_OUT" to=".J2 > .VOUT" />
  <trace from=".J2 > .GND" to="net.GND" />
  <trace from=".CIN > .pin1" to="net.VBUS" />
  <trace from=".CIN > .pin2" to="net.GND" />
  <trace from=".COUT > .pin1" to="net.PD_OUT" />
  <trace from=".COUT > .pin2" to="net.GND" />

  <trace from="net.PD_OUT" to=".RLED > .pin1" />
  <trace from=".RLED > .pin2" to=".LED1 > .anode" />
  <trace from=".LED1 > .cathode" to="net.GND" />
</RaspberryPiHatBoard>
)

Bill of materials

Ref	Part	Notes
J1	USB-C receptacle	Must expose VBUS, GND, CC1, CC2
U1	CH224K / FP28XX / PD2001	USB PD trigger/controller
R1/R2	Configuration resistors	Match values to the controller datasheet voltage table
J2	2-pin terminal block	Negotiated output and ground
LED1/RLED	Green LED + 2.2 kΩ resistor	Output-present indicator
CIN	10 µF capacitor	Input VBUS filtering
COUT	47 µF capacitor	Output bulk filtering

Example voltage-selection code/comments

Most fixed-voltage trigger chips do not need firmware; they use resistor straps or mode pins. If you are documenting the board in code, keep the selected voltage explicit:

const pdTriggerConfig = {
  controller: "CH224K",
  requestedVoltage: "12V",
  warning: "PD_OUT is not connected to Raspberry Pi 5V pins",
}

If your design uses a microcontroller-controlled PD sink instead of a fixed trigger chip, initialize the controller for the same voltage before enabling the downstream load:

// Pseudocode: use the library for your actual PD sink controller.
pd.begin();
pd.requestFixedVoltage(12); // request 12 V PDO
if (pd.contractReady()) {
  enableLoadSwitch();
}

PCB layout guidance

• Route VBUS and PD_OUT with wide traces or pours sized for the expected current.
• Keep CC1 and CC2 short and away from noisy switching nodes.
• Place CIN close to the PD controller VBUS pin and COUT close to the terminal block/load path.
• Put the selected voltage on silkscreen next to the terminal block.
• Keep the high-voltage terminal output physically separated from Raspberry Pi GPIO pins.
• Add mounting holes or strain relief if the terminal block will drive moving wires.

Bring-up and testing procedure

1. Before plugging in USB-C, check continuity: no short from VBUS/PD_OUT to ground.
2. Plug into a current-limited USB-C PD source if available.
3. Measure PD_OUT with no load and confirm it matches the selected voltage.
4. Confirm the status LED turns on only when output is present.
5. Test first with a dummy load sized for the selected voltage.
6. Only connect project hardware after confirming voltage, polarity, and current draw.

Safety notes

• A 20 V PD output can destroy 5 V electronics instantly. Label the selected voltage clearly.
• Use capacitors with voltage ratings above the requested PD voltage.
• Do not backfeed the Raspberry Pi through GPIO, 5 V, or USB ports from PD_OUT unless you add a proper regulator and power-path design.