USB 5V and External Voltage on my PCB

Projects General Guidance
1

I have a PCB that I made for a remote power supply and monitoring system. I have an ESP32 chip on it that is to be programmed using a USB-UART port.
Since the system is remote, I have 12v to 5v regulators on the board as well to act as the external power supply. When I connect the USB cable, I get a notification that the power that my PCB has exceeded the power limits of the USB port.

What could be the issue? Is it the diode? or what did i miss out on in the design? I used the espressif wroom-32 schematic as a guide for my PCB.
Also what can I do to solve the issue? The PCB is due next week and was shipped in from China so I don't have much time.

2D_PCB1_2025-04-18
2D_PCB1_2025-04-182160×2159 282 KB

SCH_Pow
Screenshot (260)
er Regulators and Monitoring_2025-05-25.pdf|attachment (221.6 KB)

2

What is 'giving' the error message?

3

WhatsApp Image 2025-05-25 at 19.56.23_79a53d54
WhatsApp Image 2025-05-25 at 19.56.23_79a53d541280×720 136 KB

My laptop

4
  1. Have you tried a diferent laptop?
  2. Measure the current flowing into the USB to see if it exceeds the spec.
5

What would be specifications be in my case?

6

To be clear do you mean with the board also fed with 12V power or do you mean powered only from the USB cable?

If only the USB cable then how do you know that the power consumption of the board is less than USB can provide?

Please post your complete schematic. If your software has the capability to export the drawing as a jpeg file please use that.

Edit, sorry, I see you did post the full schematic.

7

The Schottky diodes of the two buck converters are the wrong way round, shorting the power rail.
Leo..

8

What is connected externally?

9

IMG_4017
IMG_40171920×1376 81.5 KB

Edit:
Wawa said it first.

10

I don't know off the top of my head, but you can either get it from your laptop, or look up the USB 2 or 3 whichever applies spec on-line.
Off the top of my head, 500 mA for USB 2 or 900 mA for USB 3. What does the PCB do? You designed it, so you should know. As a designer, you should own a current meter or, at a minimum, a VOM. I also use several varieties of USB-specific power measuring dongles.

11

whoa. Thank you for noting this. Could it be the reason why the USB is drawing more power than can be accommodated?

I will correct that within the course of the week and get back on the results.

12

there is an input from a 12V battery that is to be stepped down to 5V to power the ESP32 remotely. I haven't connected the battery yet because I wanted to upload my code onto the ESP through the USB.

13

Yes. The 5dolt rail is now shorted to ground via the inductor and the diode.
Leo..

14

I resoldered the diodes in the correct way and it worked. Thanks a lot.