Building a USB Power Delivery Trigger HAT

Overview

This tutorial walks through a compact USB Power Delivery trigger HAT.

The board is designed to:

1. Accept power over USB-C
2. Negotiate a selectable PD voltage, from 5V up to 20V
3. Expose the output on terminal block connectors
4. Include a status LED
5. Add filtering capacitors for cleaner power delivery

1. Full circuit

Here is the complete HAT layout at a glance.

2. Power input and PD negotiation

The USB-C connector brings power into the board. A dedicated PD trigger controller then asks the source for the voltage you want.

For this tutorial, the controller is represented as a compact 8-pin device with:

• CC1 and CC2 for the USB-C negotiation pins
• SEL0 and SEL1 for output voltage selection
• VBUS_IN and VBUS_OUT for the power path
• LED for the status indicator

The exact PD controller part can vary. CH224K, FP28XX, and PD2001 families are all common examples that fit this style of board.

3. Add the output terminals

The output should be easy to cable into other gear, so this HAT uses a two-position terminal-style connector for the negotiated supply.

That gives you a clear VOUT+ and GND output pair without crowding the rest of the board.

4. Add filtering and status parts

The large bulk capacitor smooths load transients. The smaller bypass capacitor keeps the rail cleaner right at the controller output.

The status LED gives you a quick visual check that the controller is alive and the rail is active.

import { RaspberryPiHatBoard } from "@tscircuit/common"

export default () => (
<RaspberryPiHatBoard name="HAT1">
  <connector name="J1" standard="usb_c" />

  <chip
    name="U1"
    footprint="soic8"
    manufacturerPartNumber="CH224K"
    pinLabels={{
      pin1: "CC1",
      pin2: "CC2",
      pin3: "SEL1",
      pin4: "SEL0",
      pin5: "GND",
      pin6: "VBUS_IN",
      pin7: "VBUS_OUT",
      pin8: "LED",
    }}
    schPinArrangement={{
      leftSide: {
        direction: "top-to-bottom",
        pins: ["CC1", "CC2", "GND", "VBUS_OUT"],
      },
      rightSide: {
        direction: "top-to-bottom",
        pins: ["SEL1", "SEL0", "VBUS_IN", "LED"],
      },
    }}
  />

  <connector
    name="J2"
    pinLabels={{
      pin1: ["VOUT+"],
      pin2: ["GND"],
    }}
    schPinArrangement={{
      leftSide: {
        direction: "top-to-bottom",
        pins: ["VOUT+"],
      },
      rightSide: {
        direction: "top-to-bottom",
        pins: ["GND"],
      },
    }}
  />

  <resistor name="R1" resistance="10k" footprint="0402" />
  <capacitor name="C1" capacitance="10uF" footprint="0603" />
  <capacitor name="C2" capacitance="100nF" footprint="0402" />
  <led name="D1" color="green" footprint="0603" />

  <trace from="J1.VBUS" to="U1.VBUS_IN" />
  <trace from="J1.GND" to="net.GND" />
  <trace from="U1.VBUS_OUT" to="J2.VOUT+" />
  <trace from="J2.GND" to="net.GND" />
  <trace from="U1.VBUS_OUT" to=".HAT1_chip .V5_1" />
  <trace from="U1.GND" to=".HAT1_chip .GND_1" />
  <trace from="U1.LED" to=".D1.pos" />
  <trace from=".D1.neg" to="net.GND" />
  <trace from="U1.SEL0" to="net.VSET0" />
  <trace from="U1.SEL1" to="net.VSET1" />
</RaspberryPiHatBoard>
)

5. PCB placement

For the PCB, keep the USB-C port near the board edge and place the output connector on the opposite side so cable routing stays clean.

The controller should sit between them, with the filtering capacitors close to the output rail.

import { RaspberryPiHatBoard } from "@tscircuit/common"

export default () => (
<RaspberryPiHatBoard name="HAT1">
  <connector name="J1" standard="usb_c" pcbX={-24} pcbY={0} />

  <chip
    name="U1"
    footprint="soic8"
    manufacturerPartNumber="CH224K"
    pinLabels={{
      pin1: "CC1",
      pin2: "CC2",
      pin3: "SEL1",
      pin4: "SEL0",
      pin5: "GND",
      pin6: "VBUS_IN",
      pin7: "VBUS_OUT",
      pin8: "LED",
    }}
    pcbX={0}
    pcbY={0}
  />

  <connector
    name="J2"
    pinLabels={{
      pin1: ["VOUT+"],
      pin2: ["GND"],
    }}
    footprint={
      <footprint>
        <platedhole
          name="pad1"
          portHints={["pin1"]}
          pcbX="-2.54mm"
          pcbY="0mm"
          shape="circle"
          holeDiameter="1.2mm"
          outerDiameter="2.2mm"
        />
        <platedhole
          name="pad2"
          portHints={["pin2"]}
          pcbX="2.54mm"
          pcbY="0mm"
          shape="circle"
          holeDiameter="1.2mm"
          outerDiameter="2.2mm"
        />
      </footprint>
    }
    pcbX={22}
    pcbY={0}
  />

  <connector
    name="J3"
    pinLabels={{
      pin1: ["VSET0"],
      pin2: ["VSET1"],
    }}
    footprint={
      <footprint>
        <platedhole
          name="pad1"
          portHints={["pin1"]}
          pcbX="-2.54mm"
          pcbY="0mm"
          shape="circle"
          holeDiameter="1mm"
          outerDiameter="2mm"
        />
        <platedhole
          name="pad2"
          portHints={["pin2"]}
          pcbX="2.54mm"
          pcbY="0mm"
          shape="circle"
          holeDiameter="1mm"
          outerDiameter="2mm"
        />
      </footprint>
    }
    pcbX={20}
    pcbY={12}
  />

  <trace from="U1.VBUS_OUT" to=".HAT1_chip .V5_1" />
  <trace from="U1.GND" to=".HAT1_chip .GND_1" />

  <capacitor name="C1" capacitance="10uF" footprint="0603" pcbX={-10} pcbY={10} />
  <capacitor name="C2" capacitance="100nF" footprint="0402" pcbX={-14} pcbY={10} />
  <resistor name="R1" resistance="10k" footprint="0402" pcbX={2} pcbY={12} />
  <led name="D1" color="green" footprint="0603" pcbX={8} pcbY={12} />
</RaspberryPiHatBoard>
)

6. Bill of materials

Reference	Part	Notes
J1	USB-C connector	Input power and PD negotiation
U1	PD trigger controller	Selects the output voltage
J2	Two-position terminal connector	Output rail
J3	Two-position selector header	Voltage selection straps or control pins
C1	10uF capacitor	Bulk output filtering
C2	100nF capacitor	High-frequency decoupling
R1	10k resistor	LED current limiting
D1	Green LED	Power or status indicator

7. Example control code

If your controller exposes selection pins or if you add a tiny MCU helper, this kind of code can set the desired output mode.

const int SEL0 = 2;
const int SEL1 = 3;

void setVoltageMode(int mode) {
  // 0 -> 5V, 1 -> 9V, 2 -> 12V, 3 -> 15V, 4 -> 20V
  digitalWrite(SEL0, mode & 0x01);
  digitalWrite(SEL1, (mode >> 1) & 0x01);
}

void setup() {
  pinMode(SEL0, OUTPUT);
  pinMode(SEL1, OUTPUT);

  // Default to 12V for bench testing
  setVoltageMode(2);
}

void loop() {
  // Keep the selection stable
}

8. Testing procedure

Before attaching a load, verify the output with a multimeter:

1. Plug in a USB-C PD source
2. Select a voltage mode
3. Measure VOUT+ against GND
4. Confirm the voltage matches the selected profile
5. Check that the status LED turns on
6. Attach a small resistive load and confirm the rail stays stable

9. Next steps

• Swap the controller part number for the exact PD trigger chip you prefer
• Add an EEPROM if you want the HAT to advertise itself automatically
• Expand the output section with fusing or current sensing if you want a more complete bench supply