: The gate voltage for the isolation MOSFETs must be driven approximately 6V higher than VIN (around 25V ) to fully turn on the N-channel gates via the charging IC’s ACDRV pump. 2. The Step-Down Section (3.3V & 5V Always-On)
Understanding the top architecture of the LA-C781P schematic bridges the gap between looking at a confusing green circuit board and confidently diagnosing hardware issues. Always use a current-limited DC power supply when injecting voltage during shorts to prevent fracturing the inner layers of the PCB. lac781p schematic top
If you are looking for the full document for repair purposes, it is hosted on several technical archive sites: HP COMPAQ LA-C781P Laptop Motherboard w/CPU & Fan : The gate voltage for the isolation MOSFETs