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Add USB Power Delivery Trigger HAT tutorial #628

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Add USB Power Delivery Trigger HAT tutorial
ahmedhossa20008-max May 20, 2026
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Expand USB PD trigger HAT tutorial
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170 changes: 170 additions & 0 deletions docs/tutorials/pi-hats/usb-power-delivery-trigger-hat.mdx
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---
title: Building a USB Power Delivery Trigger HAT
description: Build a Raspberry Pi HAT that negotiates USB-C Power Delivery voltages and exposes a protected, filtered terminal-block output.
---

import CircuitPreview from "@site/src/components/CircuitPreview"

## 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

```tsx
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

```tsx
<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

```tsx
<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

<CircuitPreview code={`
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:

```ts
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:

```cpp
// 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.
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