RK3328-SOM-EVB increase USB voltage?

Started by berce, June 22, 2022, 06:13:49 pm

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Do you have any suggestions about how I can safely increase the USB output voltage on RK3328-SOM-EVB?

Now it is 4.73 V with only the measurement device attached, 4,72 with a keyboard and 4.67 V with variations when a USB wifi stick is added. The current stays below 0.01 A.
The keyboard works fine, the wifi connection is dropped seconds after connecting.
It's the same for both USB-ports. Connecting an ethernet cable drops another 0.03 V.

It's independent of the images I tried: armbian provided by Olimex and Nixos-22.05 with custom device tree.

The power source is rated 5V 2A.


Possible. I think there is voltage drop on D4 (1N5822/SS34/SMA).

1. How do you power the board? Via the power jack? Try to provide a little bit more than 5V, like 5.3V-5.4V.

2. If that is not possible you can isolate D4 but make sure no other input ever goes into the board (else short circuit). Which USB (I guess it is the USB-HOST1 but still...)? Do you also use the USB-OTG1? If you only use the power jack as power input (and no other power input, and neither USB-OTG1 present), then you can isolate D4 (aka solder a wire above it).
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