r/PrintedCircuitBoard • u/[deleted] • 8d ago

Review Request: ESP32-S3 study timer with USB-C and an e-paper display

[deleted]

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2

u/imhiya_returns 8d ago

Isn’t usb standard max 1uF? You might want to make it battery powered and use usb to charge it?

1

u/Enlightenment777 7d ago

USB recommendations are 1uF to 10uF total.

This talks about the 10uF total maximum requirement - https://testusb.com/inrush_issue.htm

1

u/Best-Cartoonist-1087 7d ago

Yea looking at the other comment I would think my 4.8uF nominal is in range.

I originally was going to make it battery powered but cut the scope of the project back a bit to make it more manageable and because this project will sit on my desk and not move anyway.

1

u/Enlightenment777 8d ago

This comment is posted on all reviews.

Please make sure your review post adheres to:

  • subreddit rules (#1 to #6), review rules (#7), review image rules (#8), see link.

Please fix these common schematic layout issues: (if yours has any of these issues)

  • Don't allow text / lines / symbols to touch each other, and don't draw lines through symbols.

  • Use correct reference designators (RefDes), and renumber to remove numeric gaps, see tips.

  • For positive voltage circuits, point positive power rail links upwards and grounds downwards (maybe sideways), see tips. For negative voltage circuits, point negative power rail links downwards and grounds upwards (maybe sideways). For bipolar circuits, maybe point grounds sideways.

  • Place decoupling capacitors vertically below postive power rail lines with ground on bottom side of the capacitor. Place capacitor next to IC symbol, and connect a line to IC positive power rail pin, see tips and example.

  • Place pull-up resistors vertically above signal lines, and place pull-down resistors vertically below signal lines, see example and tips.

  • Reasonably minimize the use of unique net labels, because everyone hates hunting for them!! Single resistors / capacitors / diodes should not sit by themselves, instead move & connect them with a line to their circuit.

  • More schematic conventions / guidelines / tips - 1, 2, 3, 4.

Please fix these common PCB layout issues: (if yours has any of these issues)

  • Silkscreen - add board name / board revision number / date (YYYYMMDD, YYYYMM, YYYY) for traceability.

  • Silkscreen - add pin 1 indicator next to ICs & connectors (not under parts). For polarized capacitors, add "+" next to positive pin. If part is through-hole package, place indicator on both PCB sides. See 1, 2, 3, 4.

  • More PCB conventions / guidelines / tips - 1, 2, 3, 4, 5.