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Abstract:
This video presents an updated version of a custom-designed USB Power Delivery (PD) breadboard power supply PCB. The creator details minor but important design fixes implemented in this new white-colored version. Key updates include adding a 1 Megaohm resistor between the USB shield and ground, rerouting resistors R7 and R8 and changing R8's value to create a voltage clamping fail-safe (defaulting to 5V if the switch fails), and correcting a typo on the silkscreen. The core functionality relies on the CH224K chip to negotiate voltages from 5V to 20V (up to 100W) with compatible USB PD chargers, selectable via a DIP switch. The board provides the negotiated voltage via screw terminals and offers switchable 3.3V or 5V regulated rails for breadboard use. Assembly footage showcases the SMD reflow process. Testing confirms successful PD voltage negotiation but reveals slight inaccuracies in the 3.3V and 5V regulated outputs, attributed to using a readily available 56kΩ resistor for R8 instead of the specified 57.6kΩ. The creator shares project resources on PCBWay.
Updated USB PD Breadboard Power Supply: Design Fixes and Testing
0:00:05 Project Introduction: The video showcases an updated version of a USB PD breadboard power supply, motivated by fixing minor design flaws from the previous iteration and trying a new white PCB color.
0:00:26 Update 1 - Shield Resistor: An extra 1 Megaohm resistor was added between the USB connector shield and ground for improved design practice.
0:00:42 Update 2 - Voltage Rail Fail-Safe: Resistors R7 and R8 were rerouted, and R8's value changed. This ensures the regulated output defaults to a specific voltage (5V in this version) if the 3.3V/5V selection switch fails or is positioned incorrectly.
0:01:11 Update 3 - Silkscreen Typo Fix: A typo on the back silkscreen ("USD") was corrected to "USB".
0:01:32 Core Functionality: The design uses the CH224K chip to negotiate USB PD voltages (5V to 20V, up to 100W) from a compatible power supply.
0:02:03 Assembly Showcase: Brief footage shows the process of assembling the surface-mount components using solder paste and a reflow heat source. Through-hole components were soldered separately off-camera.
0:06:12 Project Resources: The creator directs viewers to their PCBWay project page for schematics, BoM, and Gerber files to recreate or order the board.
0:06:35 Board Features: The board includes a USB-C input, screw terminals for the negotiated high-power output, a toggle switch for selecting 3.3V or 5V on the breadboard rails, and a 3-position DIP switch to set the requested PD voltage.
0:07:06 Assembly Detail - R8 Mismatch: The creator notes they used an 0805 size 56kΩ resistor for R8 instead of the intended 0603 size 57.6kΩ resistor due to availability, resulting in a slight physical misfit.
0:07:33 PD Voltage Negotiation Test: Testing with a USB PD power supply confirms the board successfully negotiates and outputs the selected voltages (9V, 12V, 15V, 20V, 5V) at the screw terminals based on DIP switch settings.
0:08:24 Regulated Rail Voltage Test & Issue: The 3.3V rail measures ~3.2V, and the 5V rail measures ~4.8V. This slight inaccuracy is directly attributed to using the 56kΩ resistor for R8 instead of the specified 57.6kΩ needed for the updated fail-safe circuit.
0:09:04 Troubleshooting Recap: The creator explains the initial confusion when the 3.3V rail read 2.3V because they initially used the old R8 value (23.2kΩ) before remembering the design change required the new ~57.6kΩ value.