Hi all!

This log is to define the goals for this project. I want to establish what the design objectives of the StampPCB will be.

Objectives

• A drop in PCB Stamp that requires no extra hardware to function (excluding USB-C Port)
  • USB-C Port is excluded from the Stamp to allow for variable position of the stamp relative to USB-C Port if needed
• Programmable voltage and current (no resistor settings)
  • Ideally as high voltage and current as reasonable (thinking 28V, 5A)
  • As many different ways to control the power as possible
• Easy communication with stamp to change the voltage and current configuration
  • Want the widest compatibility with as many microcontrollers as reasonably possible
  • Must use a common communication standard such as I2C, SPI, UART, etc
  • Drop in library for at least RP2XXX microcontrollers
• Constant 3.3V and 5.0V output pins allow for power-on of microcontrollers independently of selected USB power configuration
  • Allows for control of USB PD power configuration through the microcontroller without worrying about effecting the microcontroller
  • Addition of both 3.3V and 5.0V for wider compatibility with different microcontrollers
  • Pins output enough current to power most microcontrollers plus other components (thinking 1A currently)
• Smallest reasonable board area
• • Less than 20x20mm if possible
• Reasonable cost (Ideally less than $20 for 5 boards or more)
  • Possible reduced cost version without 3.3V and 5.0V output pins as well as any other optional components
  • Limit PCB to 2-4 layers
• Stamp pins must be hand solderable
  • Components on stamp may not be hand solderable through will try to make as many components hand solderable as possible
• Microprocessor Agnostic

Inspiration

This project was inspired by the PicoPD. This board adds USB-C Power Delivery to a RP2040. Want variability in the USB-C PD just like this board.

The stamp design is inspired by the RP2350 Stamp. Want a drop in component just like this stamp.

Early Part Choice

Current part choices are influenced by the PicoPD. Want to upgrade from the AP33772 to the AP33772S for a more up to date PD spec (PD3.0 vs PD3.1). This allows for an increase from 100W (20V, 5A) to 140W (28V, 5A) as well as a couple other features. The downside is that there is less fine grain control of the voltage and amperage (20mV vs 100mV increments and 50mA vs 250mA increments)

Current Part Choice

• 1x AP33772S (USB PD3.1 Sink Controller)
• 1x TPD4E5U06DQAR (ESD Protection Diodes)
• 1x 5.0V LDO Regulator (separate constant power for 5.0V output pin)
• 1x 3.3V LDO Regulator (separate constant power for 3.3V output pin)
• 1x NTC Thermistor (Over Temperature Protection Detection, programmable)
• 2x 5.1k Resistors for CC1 and CC2 USB pins to ground
• 2x LED's to show USB-C Power and AP33772S Power
• ?x Resistors and Capacitors

Future Usage of StampPD

While StampPD is designed to be as microprocessor agnostic as I can make it, I do have a board I want to build with it in mind. That board currently uses the RP2350 Stamp with StampPD and a third USB-PD High Power GPIO Stamp to allow the RP2350 to control pins at the max power of StampPD. This project will come after StampPD is finished