I set up miniature Halloween and Christmas Villages. One of the larger manufacturers is switching to having their pieces powered by USB A or C ports instead of DC barrell connections. They appear to just draw power from the charger or port without any kind of USB compliant negotiation, the ones with USB C ports don’t even have the 5.1K pulldown resistors to request default power from the charger. My understanding is they should work when using a A to C cable, but not with a C to C cable, yet they do. Do the makers of USB C chargers actually have them output power even without the required pulldown resistors in the load device, or is my whole understanding of this incorrect?
No resistors → no power
Why do you think there is nothing there, though?
I don’t see any resistors between the pins in the device- there’s just two wires connected to the jack, and I used a breakout box to measure resistance between ground and and the other pins with an ohmmeter and didn’t get anything.
You wouldn’t see anything in the device - they go on the data lines. Low-wattage surface mount devices can easily fit inside the USB plug itself.
The resistance should be between CC and ground.
I would expect a typical rating of 5 vdc @ 500 mA on a lousy charger and, as said, without further negotiation.
I recommend an test instrument, I have one like below but there are other kinds:
You’re correct: on the device/load that is being powered, there must be a 5.1 kΩ resistor between CC1 and ground, and a 5.1 kΩ resistor between CC2 and ground, if the power source has a USB-C connector and is USB-C compliant.
It’s a mystery if you’re getting 5 V without the resistors. Is it possible the USB-C to USB-C cable is e-marked? If so, one of the connectors on the cable contains a 5.1 kΩ resistor between CC and ground.