As reported on some VLab forums , the LA-C391P can experience charging issues where the battery shows as "plugged in, not charging".
+------------------+ +------------------+ | EC BIOS Chip | | MAIN BIOS Chip | | (Winbond 25Q64) | | (Winbond 25Q128) | +--------+---------+ +--------+---------+ | | +------------+---------------+ | [Embedded Controller / PCH]
Result 0 from the same search is a "component replacement" thread on HP's community forum, which mentions "APW70-LA-C391P" and a broken LED near the power supply input. This confirms the motherboard model. apw70 lac391p schematic portable
Keep in mind that designing a portable device with a power management IC like the APW70 LAC391P requires expertise in power electronics, analog design, and system integration.
Always start on page 2 or 3 of the PDF. The block diagram gives you a birds-eye view of how the system buses interconnect, identifying which page numbers host specific elements like the charging circuit, audio codecs, or BIOS chip. As reported on some VLab forums , the
When the power button is triggered, the EC pulses a wake signal that enables downstream power rails: : Stabilizes the DDR4 memory system.
Verify secondary voltages like memory power or system agent rails. If the APW70 is responsible for generating these specific rails, check the FB (Feedback) loop to ensure resistors have not drifted in value. Step-by-Step Troubleshooting Process Keep in mind that designing a portable device
: The 3.3V and 5.0V Always-On rails managed by a dedicated Power Management Integrated Circuit (PMIC) step-down controller. If these are missing, the Embedded Controller (EC/Super I/O) chip will not boot. Suspend and Run Rails (S3 to S0 State)
The input power flows from the DC-IN jack through the input protection MOSFETs.
Embedded Controller (EC) manages the initial power-on logic before handing off control to the main chipset. Decoding the APW70 Power IC in Portable Schematics
APW70 LAC391P is a motherboard model used in the Dell Latitude 3510