Does you 25W PSU have a 5V/5A mode that can be negotiated via USB PD?
If not, current available to conected USB devices will be restricted to a combined maximum of 600mA which probably won't be enough to run an external HDD.
It can be overridden in config.txt by adding the following to the end of it:IIRC there's also an EEPROM setting that has the same effect.
If your 96W Mac charger lacks that mode the same thing will happen.
The wattage rating of PD PSU is (possibly intentionally) confusing. It's the maximum rating for the PSU but for anything more than 25W (15W if 5V/5A is not supported) it has to supply the same current at a higher voltage than 5V. The cable and connector is only rated for 5A regardless of voltage.
If the desired mode cannot be negotiated or the sink device is not capable of PD you get 5V/3A.
If not, current available to conected USB devices will be restricted to a combined maximum of 600mA which probably won't be enough to run an external HDD.
It can be overridden in config.txt by adding the following to the end of it:
Code:
usb_max_current_enable=1If your 96W Mac charger lacks that mode the same thing will happen.
The wattage rating of PD PSU is (possibly intentionally) confusing. It's the maximum rating for the PSU but for anything more than 25W (15W if 5V/5A is not supported) it has to supply the same current at a higher voltage than 5V. The cable and connector is only rated for 5A regardless of voltage.
If the desired mode cannot be negotiated or the sink device is not capable of PD you get 5V/3A.
Statistics: Posted by thagrol — Mon Jun 10, 2024 8:55 pm
