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341 changes: 341 additions & 0 deletions docs/tutorials/pi-hats/usb-pd-trigger-hat.mdx
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---
title: Building a USB Power Delivery Trigger HAT
description: Learn how to build a USB Power Delivery trigger HAT for Raspberry Pi that negotiates 5V-20V from USB-C PD power supplies using tscircuit.
---

## Overview

This tutorial will walk you through building a USB Power Delivery (PD) trigger HAT for Raspberry Pi. The HAT uses a CH224K controller to negotiate voltage from USB-C PD power supplies, providing configurable 5V to 20V output.

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

<TscircuitIframe defaultView="3d" code={`
export default () => (
<board width="65mm" height="30mm">
{/* USB-C Connector */}
<chip
name="J1"
footprint="usb_c_16pin"
pinLabels={{
pin1: "GND",
pin2: "VBUS",
pin3: "CC1",
pin4: "CC2",
pin5: "D+",
pin6: "D-",
pin7: "SBU1",
pin8: "SBU2"
}}
pcbX={-25}
pcbY={0}
/>

{/* CH224K USB PD Controller */}
<chip
name="U1"
footprint="essop10"
pinLabels={{
pin1: "CFG1",
pin2: "CFG2",
pin3: "CFG3",
pin4: "CC1",
pin5: "CC2",
pin6: "VIN",
pin7: "GND",
pin8: "VOUT",
pin9: "PG",
pin10: "NC"
}}
schPortArrangement={{
leftSide: { pins: ["VIN", "CC1", "CC2", "GND", "NC"] },
rightSide: { pins: ["VOUT", "PG", "CFG1", "CFG2", "CFG3"] }
}}
pcbX={-5}
pcbY={0}
/>

{/* Status LED */}
<led name="LED1" color="green" footprint="0603" pcbX={10} pcbY={5} />
<resistor name="R1" resistance="1k" footprint="0402" pcbX={10} pcbY={0} />

{/* Output Capacitors */}
<capacitor name="C1" capacitance="10uF" footprint="0805" pcbX={15} pcbY={-5} />
<capacitor name="C2" capacitance="100nF" footprint="0402" pcbX={20} pcbY={-5} />

{/* Terminal Block Output */}
<pinheader name="J2" pinCount={2} pitch="5.08mm" pcbX={25} pcbY={0} />

{/* Raspberry Pi GPIO Header */}
<pinheader name="J3" pinCount={40} pitch="2.54mm" pcbX={0} pcbY={10} />

{/* Power traces */}
<trace from=".J1 .VBUS" to=".U1 .VIN" />
<trace from=".J1 .CC1" to=".U1 .CC1" />
<trace from=".J1 .CC2" to=".U1 .CC2" />
<trace from=".J1 .GND" to="net.GND" />
<trace from=".U1 .GND" to="net.GND" />

{/* Output connections */}
<trace from=".U1 .VOUT" to=".J2 .pin1" />
<trace from=".J2 .pin2" to="net.GND" />

{/* Capacitor connections */}
<trace from=".C1 .pos" to=".U1 .VOUT" />
<trace from=".C1 .neg" to="net.GND" />
<trace from=".C2 .pos" to=".U1 .VOUT" />
<trace from=".C2 .neg" to="net.GND" />

{/* Status LED */}
<trace from=".U1 .PG" to=".R1 .pos" />
<trace from=".R1 .neg" to=".LED1 .pos" />
<trace from=".LED1 .neg" to="net.GND" />
</board>
)
`} />

## Objectives

A USB PD trigger HAT demonstrates advanced power electronics concepts:

- **USB Power Delivery Protocol** - Understanding PD negotiation
- **Voltage Selection** - Configuring output voltage via pins
- **Power Distribution** - Safe delivery of higher voltages
- **HAT Design** - Raspberry Pi expansion board conventions

## Use Cases

- **High Power Projects** - Power motors, heaters, or high-brightness LEDs
- **Battery Charging** - Build chargers for various battery chemistries
- **Lab Power Supply** - Portable voltage source from USB-C chargers
- **Raspberry Pi Clusters** - Efficient power for multiple Pis

## Bill of Materials

| Component | Value | Footprint | Purpose |
|-----------|-------|-----------|---------|
| USB-C Connector | - | 16-pin | PD power input |
| CH224K | - | ESSOP-10 | PD controller |
| LED1 | Green | 0603 | Power good indicator |
| R1 | 1kΩ | 0402 | LED current limit |
| C1 | 10µF | 0805 | Output filtering |
| C2 | 100nF | 0402 | High-freq filtering |
| J2 | 2-pin | 5.08mm | Terminal block output |
| J3 | 40-pin | 2.54mm | Raspberry Pi header |

## Understanding USB Power Delivery

USB PD allows negotiation of higher voltages and currents:

| Profile | Voltage | Max Current | Max Power |
|---------|---------|-------------|-----------|
| 5V | 5V | 3A | 15W |
| 9V | 9V | 3A | 27W |
| 12V | 12V | 3A | 36W |
| 15V | 15V | 3A | 45W |
| 20V | 20V | 5A | 100W |

The CH224K handles all PD communication automatically.

## Circuit Design

### Step 1: CH224K Voltage Configuration

The CH224K selects output voltage based on CFG pin connections:

| CFG3 | CFG2 | CFG1 | Output Voltage |
|------|------|------|----------------|
| Float | Float | Float | 5V |
| Float | Float | GND | 9V |
| Float | GND | Float | 12V |
| Float | GND | GND | 15V |
| GND | Float | Float | 20V |

<CircuitPreview splitView={false} hidePCBTab hide3DTab defaultView="schematic" code={`
export default () => (
<board width="30mm" height="25mm">
<chip
name="U1"
footprint="essop10"
pinLabels={{
pin1: "CFG1",
pin2: "CFG2",
pin3: "CFG3",
pin4: "CC1",
pin5: "CC2",
pin6: "VIN",
pin7: "GND",
pin8: "VOUT",
pin9: "PG",
pin10: "NC"
}}
schPortArrangement={{
leftSide: { pins: ["VIN", "CC1", "CC2", "GND", "NC"] },
rightSide: { pins: ["VOUT", "PG", "CFG1", "CFG2", "CFG3"] }
}}
/>

{/* Example: 12V configuration (CFG2 to GND) */}
<trace from=".U1 .CFG2" to="net.GND" />
<trace from=".U1 .GND" to="net.GND" />
</board>
)
`} />

### Step 2: USB-C Connection

Connect the USB-C CC pins to the controller for PD communication:

<CircuitPreview splitView={false} hidePCBTab hide3DTab defaultView="schematic" code={`
export default () => (
<board width="30mm" height="25mm">
<chip
name="J1"
footprint="usb_c_16pin"
pinLabels={{
pin1: "GND",
pin2: "VBUS",
pin3: "CC1",
pin4: "CC2"
}}
/>

<chip
name="U1"
footprint="essop10"
pinLabels={{
pin4: "CC1",
pin5: "CC2",
pin6: "VIN",
pin7: "GND"
}}
schX={5}
/>

<trace from=".J1 .VBUS" to=".U1 .VIN" />
<trace from=".J1 .CC1" to=".U1 .CC1" />
<trace from=".J1 .CC2" to=".U1 .CC2" />
<trace from=".J1 .GND" to="net.GND" />
<trace from=".U1 .GND" to="net.GND" />
</board>
)
`} />

### Step 3: Output Filtering

Output capacitors ensure stable voltage delivery:

<CircuitPreview splitView={false} hidePCBTab hide3DTab defaultView="schematic" code={`
export default () => (
<board width="30mm" height="25mm">
<capacitor name="C1" capacitance="10uF" footprint="0805" />
<capacitor name="C2" capacitance="100nF" footprint="0402" schX={4} />

<trace from=".C1 .pos" to="net.VOUT" />
<trace from=".C1 .neg" to="net.GND" />
<trace from=".C2 .pos" to="net.VOUT" />
<trace from=".C2 .neg" to="net.GND" />
</board>
)
`} />

### Step 4: Power Good LED

The PG pin indicates successful voltage negotiation:

<CircuitPreview splitView={false} hidePCBTab hide3DTab defaultView="schematic" code={`
export default () => (
<board width="30mm" height="25mm">
<resistor name="R1" resistance="1k" footprint="0402" />
<led name="LED1" color="green" footprint="0603" schX={5} />

<trace from="net.PG" to=".R1 .pos" />
<trace from=".R1 .neg" to=".LED1 .pos" />
<trace from=".LED1 .neg" to="net.GND" />
</board>
)
`} />

## Complete Schematic

<CircuitPreview splitView={false} hidePCBTab hide3DTab defaultView="schematic" code={`
export default () => (
<board width="65mm" height="30mm">
<chip
name="J1"
footprint="usb_c_16pin"
pinLabels={{
pin1: "GND",
pin2: "VBUS",
pin3: "CC1",
pin4: "CC2"
}}
schX={-10}
/>

<chip
name="U1"
footprint="essop10"
pinLabels={{
pin1: "CFG1",
pin2: "CFG2",
pin3: "CFG3",
pin4: "CC1",
pin5: "CC2",
pin6: "VIN",
pin7: "GND",
pin8: "VOUT",
pin9: "PG",
pin10: "NC"
}}
schPortArrangement={{
leftSide: { pins: ["VIN", "CC1", "CC2", "GND", "NC"] },
rightSide: { pins: ["VOUT", "PG", "CFG1", "CFG2", "CFG3"] }
}}
/>

<led name="LED1" color="green" footprint="0603" schX={10} schY={-3} />
<resistor name="R1" resistance="1k" footprint="0402" schX={7} schY={-3} />
<capacitor name="C1" capacitance="10uF" footprint="0805" schX={8} />
<capacitor name="C2" capacitance="100nF" footprint="0402" schX={12} />
<pinheader name="J2" pinCount={2} pitch="5.08mm" schX={15} />

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

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

<trace from=".C1 .pos" to=".U1 .VOUT" />
<trace from=".C1 .neg" to="net.GND" />
<trace from=".C2 .pos" to=".U1 .VOUT" />
<trace from=".C2 .neg" to="net.GND" />

<trace from=".U1 .PG" to=".R1 .pos" />
<trace from=".R1 .neg" to=".LED1 .pos" />
<trace from=".LED1 .neg" to="net.GND" />
</board>
)
`} />

## Testing the HAT

1. **Visual Inspection** - Check solder joints and component orientation
2. **Continuity Test** - Verify no shorts between VOUT and GND
3. **Power Test** - Connect to a USB-C PD charger
4. **LED Check** - Green LED should illuminate when voltage is negotiated
5. **Voltage Verify** - Measure output with a multimeter

## Safety Considerations

- Always verify voltage before connecting loads
- Use appropriate gauge wires for high current
- Include reverse polarity protection for sensitive loads
- Consider adding a fuse for overcurrent protection

## Ordering the PCB

Export the fabrication files and upload to JLCPCB. See [Ordering Prototypes](/building-electronics/ordering-prototypes) for detailed instructions.
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