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Raspberry Pi HATs

Building a USB Power Delivery Trigger HAT

Overview​

This tutorial designs a USB Power Delivery trigger HAT. The board uses a USB-C connector and PD trigger controller to request a fixed voltage, then exposes the negotiated output through filtering and a terminal block.

Use this pattern for projects that need a USB-C power source at 9 V, 12 V, 15 V, or 20 V. Do not connect the negotiated high-voltage rail directly to Raspberry Pi 5 V pins.

Requirements​

  • USB-C receptacle.
  • PD trigger/controller such as CH224K, FP28XX, or PD2001.
  • Configuration resistors or pins for voltage selection.
  • Terminal block output.
  • Status LED with current-limiting resistor.
  • Input and output capacitors.

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" pcbX={-22} pcbY={0} />
<chip name="U1" footprint="sop10" manufacturerPartNumber="CH224K USB PD trigger" pcbX={-6} pcbY={0} />

Step 3: Add voltage selection and output parts​

<resistor name="R1" resistance="10k" footprint="0402" pcbX={2} pcbY={8} />
<resistor name="R2" resistance="10k" footprint="0402" pcbX={2} pcbY={4} />
<chip name="J2" footprint="terminalblock_2" manufacturerPartNumber="PD output" pcbX={20} pcbY={0} />
<led name="LED1" footprint="0603" color="green" pcbX={10} pcbY={8} />
<resistor name="R3" resistance="2.2k" footprint="0402" pcbX={14} pcbY={8} />

Complete example​

import { RaspberryPiHatBoard } from "@tscircuit/common"

export default () => (
  <RaspberryPiHatBoard name="HAT1">
    <chip name="J1" footprint="usb_c_receptacle" manufacturerPartNumber="USB-C receptacle" pcbX={-22} pcbY={0} />
    <chip name="U1" footprint="sop10" manufacturerPartNumber="CH224K USB PD trigger" pcbX={-6} pcbY={0} />
    <chip name="J2" footprint="terminalblock_2" manufacturerPartNumber="PD output" pcbX={20} pcbY={0} />
    <resistor name="R1" resistance="10k" footprint="0402" pcbX={2} pcbY={8} />
    <resistor name="R2" resistance="10k" footprint="0402" pcbX={2} pcbY={4} />
    <resistor name="R3" resistance="2.2k" footprint="0402" pcbX={14} pcbY={8} />
    <led name="LED1" footprint="0603" color="green" pcbX={10} pcbY={8} />
    <capacitor name="C1" capacitance="10uF" footprint="0603" pcbX={-12} pcbY={8} />
    <capacitor name="C2" capacitance="47uF" footprint="cap_0603" pcbX={12} pcbY={-8} />
    <trace from=".J1 > .pin1" to=".U1 > .pin1" />
    <trace from=".J1 > .pin3" to=".U1 > .pin3" />
    <trace from=".J1 > .pin4" to=".U1 > .pin4" />
    <trace from=".U1 > .pin9" to=".J2 > .pin1" />
    <trace from=".U1 > .pin10" to=".J2 > .pin2" />
  </RaspberryPiHatBoard>
)

Layout and bring-up checklist​

  • Use wide traces for VBUS and the negotiated output.
  • Place input capacitance close to the controller VIN pin.
  • Place output capacitance close to the terminal block.
  • Add silkscreen text showing the configured output voltage.
  • Measure the terminal voltage before connecting a load.
  • Test first with a small dummy load before attaching project hardware.