Hi, I’m traying to power on VisionFive2 with power supply 5.2V - 3.0 A and 5V - 5A and I ca’nt get. Red light is on but not green light. Does anyone knows why? Thanks.
There are a lot of potential issues, but I think it is easier when you tell us more about your situation.
Are you trying to boot from micro SD, eMMC, or NVMe?
Which image are you trying to boot?
If you are booting from micro SD or eMMC, power should not be the issue.
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Which image ?
If using the latest, did you change the switches to read latest the SPL+U-boot and U-boot+OpenSBI directly from the SD card (or eMMC). Because the default ones that were written to the onboard QSPI NOR FLASH (switches default position when shipped) will not allow you to boot the latest image without being updated first.
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Ok, changing switches.
If a straight voltage, has to be 5.5V or over for the NB679 regulator.
Recommended Supply voltage … 5.5 V to 24 V
(The device is not guaranteed to function outside of its operating conditions)
USB-C connector, generally up to 3 or 5 Amp
so… 5V 5A up to 25W
12V 3A gives ~35W which is suggested for the VF2
or 20V 2A gives 40W
I’ll keep it in mind, thanks.
Worth noting that the NB679 will only start switching/regulating properly at 5.5v, but it will still hold it’s internal switching mosfet ‘on’ and allow the full supply to pass through relatively unimpeded at lower voltages.
This is why the board will work even if you have a classic 5v USB supply. You are, however, really vulnerable to voltage dips if doing this, probably OK running from the SD but add a NVMe or some high power USB devices and you should pretty much expect problems unless the adapter and cabling are really solid. A proper USB-PD supply is the only way to be certain.
PS: If anyone is looking at the schematics page for the USB-C supply and wondering what this is:
It’s an ‘ideal diode’ that sits after the DC converter, and it’s ‘anode’ is the master 5v power rail for the whole board (incl. USB, fan and GPIO power). It works just like a regular diode but has (effectively) no forward voltage drop, no reverse leakage, and a higher breakdown threshold. It puzzled me so I went and, eventually, found out that ‘ideal diodes’ are a thing. The resistor,
r91284 that can bypass this is NC (not fitted).
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Thanks for explanation. Now I’m using a proper USB-PD supply. Before this, with low volatge (5v) I had problems with monitor.
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