A USB-C Power Delivery (PD) trigger board lets you pull higher voltages (9V, 12V, 15V, or 20V) from a standard USB-C charger or power bank. This is incredibly useful for powering portable projects, motors, and LED strips.

How USB-C PD Works:
By default, USB-C only provides 5V. To request higher voltages, the device must communicate over the CC (Configuration Channel) line using a BMC-based protocol called PD. A trigger board emulates this negotiation automatically.

How a Trigger Board Works:
The trigger board contains a small PD controller IC (such as the HUSB238, FUSB302, or IP2721). When plugged into a PD source, it sends a request for your selected voltage. The adapter then steps up its output to the requested level.

Common PD Trigger ICs:
- HUSB238: Simple, DIP or SOP package, voltage select via buttons or pins.
- FUSB302: Needs an MCU, more flexible for custom projects.
- IP2721: Similar to HUSB238, supports wide voltage range.

Design Considerations:
1. Input: USB-C female connector with CC1 and CC2 connected to the PD IC.
2. Voltage selection: Use slide switches or push buttons to set desired PDO.
3. Output: Add a 5.5x2.1mm barrel jack or screw terminals for easy connection.
4. Protection: Add a fuse and TVS diode on the output for safety.
5. Indicator: Add an LED to show active voltage level.

Typical Applications:
- Powering 12V LED strips from a USB-C laptop charger.
- Running small DC motors or pumps.
- Bench power supply for prototyping.
- Charging other devices that need 9V or 15V.

A well-designed PD trigger board is a small but powerful addition to any electronics workshop.