Specialized ICs handle the Quick Charge 3.0 or Power Delivery protocols by communicating with connected devices via the USB data lines to negotiate higher voltages (9V/12V).
But we’re not most people. Today, we’re tracing the board, mapping the schematic, and figuring out how this budget workhorse actually ticks. wlx-896b schematic
One or two 150kΩ resistors from the bulk cap’s positive to pin 7 of the UC3842. If these drift open, the chip never starts. Specialized ICs handle the Quick Charge 3
Understanding the schematic begins with its power capabilities and interface layout: 40W (Maximum). One or two 150kΩ resistors from the bulk
The TL431’s cathode pulls the optocoupler LED. The phototransistor side goes to pin 2 (inverting input) of the UC3842. A 10kΩ resistor from pin 2 to ground sets the reference. Changing this resistor changes the output voltage.