The PS4 never truly turns "off" in the traditional sense; it enters a low-power standby mode.
The magic of a regulated power supply lies in the feedback loop. On the ADP-160ER schematic, trace the output voltage (20V) through a voltage divider (resistors) into a TL431 programmable shunt regulator.
The TL431 compares a fraction of the output voltage to an internal 2.5V reference. If the voltage rises above 20V, the TL431 conducts more current. This current flows through an optocoupler (PC123 or similar) , causing its internal LED to glow brighter. Adp-160er Schematic
On the primary side, the optocoupler’s phototransistor conducts more current, pulling the FB pin of the PWM controller low. The PWM responds by reducing the duty cycle (shortening the on-time of the MOSFET), which lowers the output voltage back to 20V.
Without this feedback loop, the adapter would output 30V+ and destroy the laptop. The PS4 never truly turns "off" in the
Regulator core
Feedback & compensation
Enable / soft-start
Protection
Auxiliary circuits