Why 56k ohm pull-up resistor?
To do so, USB-C cables have a 56k ohm resistor that allows the power supply and the device plugged into it to work out the correct power level that suits both ends of the charging party, making sure the device does not draw more power than the plug can supply.
How do I test a USB cable with a multimeter?
Set the Multimeter to DCV 20 mode and it should show around 5V. If that works, then another test you can do is get a 1.5kohm resistor and connect it between either of the data wires and the hot wire while your computer is on.
What is USB IF certified?
The USB-IF cable certification program aims to provide USB end users with a list of cables that meet quality standards necessary to operate in a USB environment. All cables do not have the same capabilities. The USB-IF certifies cables for different purposes.
What kind of resistor do I need for USB Type C?
The specification table below shows what values can be used to set a specific Type-C charging mode and underneath, in the small print, we can see that a 56kΩ resistor should be used with all legacy cable connections.
Why do I need a USB Type C cable?
Because the USB Type-C standard specifically defines higher rates of charging that aren’t catered for in older Type-B or other connectors, cable manufacturers are supposed to use the CC connection and Rp resistor to ensure that devices don’t attempt to draw too much current from older chargers or devices that can’t support it.
What kind of resistor does a USB 2.0 battery pack have?
A USB 2.0 type battery pack, for example has both a type-A female and a micro-B female connector: The USB Type-C specifications (available at USB.org as “Universal Serial Bus type-C Cable and Connector Specification”) explain different resistor values for determining whether a device is sourcing or sinking current.
How does a USB 3.1 power supply work?
Rather than sending configuration data over the CC pin, the pin is pulled up to the 5V supply rail and the current coming into the pin is monitored to determine the output power requested by the device. The amount of current is controlled by the pull-up resistor Rp, and setting it to specific values sets the device to draw either 0.9A, 1.5A or 3A.