Sony laptop memory power supply circuit (SC486)

Sony laptop memory power supply circuit (SC486)

Shown is the memory power supply circuit of WN-FE53BW Sony laptop , which uses SC486 as the power management chip.     There are two sets of PWM signal generation circuits in the SC486 chip. One set outputs two PWM signals with opposite phases from the @ pin and the @ pin, which are respectively added to the gates of the two field effect transistors in Ql, so that the two field effect transistors conduct cross-conduction. Turn on, changing the battery's supply voltage into pulse voltage . After being filtered by L1 and Cl0, the voltage becomes +2.5 V to power the memory. At the same time, the +2.5 V power supply is added to the @ pin and @ pin of SC486. There is a second set of PWM signal generation circuits and two field effect transistors inside the chip. These two field effect transistors turn the 2.5 V voltage into a pulse signal, which is output by the @ pin and @ pin of SC486. After being filtered by Cl1, it outputs a 1.25 V DC voltage to power the circuit in the memory .