B638DL NB638 NB* MPS IC Marking NBDN NBAP NBDJ NBCN

NB638 / B638DL is an official MPS (Monolithic Power Systems) synchronous buck converter IC, widely used in laptop motherboards, GPU boards, high-current DC regulators and compact power rails.

It delivers high efficiency, stable output, and very low quiescent current, making it suitable for space-restricted and thermal-sensitive laptop power sections.

Supported Markings (Original MPS Codes)

This IC commonly comes with the following markings:

NBDN / NBAP / NBDJ / NBCN

All above markings are valid NB638 family identification codes used by MPS.

Technical Summary

• Type: High-efficiency synchronous buck converter IC
• Brand: MPS (Monolithic Power Systems)
• Package: QFN
• Marking: NBDN / NBAP / NBDJ / NBCN
• Application: CPU/GPU rails, system power supply, high-current DC regulators
• Features:
• Integrated high-side & low-side MOSFETs
• Precision reference & fast transient response
• Optimized for laptop and desktop VRM sections
• Very compact footprint & excellent thermal behavior
• Use Cases: Laptop motherboard repair, VRM stage replacement, DC-DC step-down applications