Monolithic Power Systems Inc. NB669GQ-P

Overview

NB669GQ-P from Monolithic Power Systems is a fully integrated 24V-input synchronous buck converter with fixed 5V/6A output, integrated 5V/100mA LDO, and 300kHz CLK output for external charge pump drive - designed for laptop and tablet power rails requiring high efficiency, fast transient response, and compact footprint.

For engineers reviewing the NB669GQ-P datasheet, NB669GQ-P pinout, NB669GQ-P application, or NB669GQ-P equivalent, this device supports critical design tasks including main system rail regulation, auxiliary 5V supply switching, gate drive voltage generation via external charge pump, and coordinated power-good signaling in space-constrained portable electronics.

Technical Context

The NB669GQ-P employs Constant-On-Time (COT) control to deliver fast load-transient response without external compensation, enabling stable operation with ceramic output capacitors. Its internal high-side (30mΩ) and low-side (15mΩ) MOSFETs support continuous 6A output at up to 500kHz switching frequency.

It integrates dual regulation paths: primary buck stage with 95–105% VOUT power-good monitoring and latch-off reset via EN or VIN cycle, plus an independent 5V LDO with switch-over logic that connects LDO output to VOUT once VOUT exceeds 4.77V - eliminating redundant regulation loss during active mode.

Key Specifications

Pinout & Package

Package: QFN16 (3mm × 3mm) with exposed thermal pad on underside for enhanced heat dissipation in high-power-density layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-current synchronous buck converter applications.

Compared with MP2315GQ-Z and RT7290AZSP, NB669GQ-P uniquely combines 6A output, integrated LDO with automatic switch-over, and dedicated 300kHz CLK - making it optimal for compact, multi-rail portable designs where minimizing discrete components and coordinating auxiliary power is critical.

Availability

NB669GQ-P is available at Aetrix Electronics and suitable for laptop computer power subsystems, tablet PC SoC supplies, and flat panel display logic rails requiring stable component supply through end-of-life transition planning.

Supply support for NB669GQ-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, motion control, and automotive applications.

The NB669GQ-P belongs to MPS's high-current integrated buck converter product line, engineered specifically for space-constrained portable electronics requiring combined main rail regulation, auxiliary LDO, and gate-drive support in a single QFN package.

FAQ

What is the function of the CLK pin on NB669GQ-P?

The CLK pin outputs a 300kHz square wave used to drive an external charge pump circuit. This allows generation of ~12–15V gate drive voltage for external load switches without drawing current from the main 5V buck output, preserving overall system efficiency and thermal margin.

How does the LDO switch-over mechanism work?

When the main buck output (VOUT) rises above 4.77V and the power-good flag asserts, the internal 5V LDO shuts off and an integrated MOSFET connects the LDO pin directly to VOUT. This switch-over occurs within 20μs and eliminates 100mA × 0.2V conduction loss during active operation while retaining fast wake-up capability.

Can NB669GQ-P operate with only ceramic output capacitors?

Yes. The NB669GQ-P includes internal ramp compensation that stabilizes Constant-On-Time control without requiring ESR-based feedback, enabling use of low-ESR ceramic capacitors exclusively - reducing output ripple, board area, and total BOM cost versus electrolytic+ceramic hybrid solutions.

What protection features are implemented and how do they reset?

It implements OCP (valley-current limit), OVP (130% trip), UVP (60% trip), thermal shutdown (150°C), and UVLO (4.65V). All fault conditions latch off the converter and require either pulling EN low or cycling VIN to reset - ensuring system safety during persistent faults.

Is the EN pin allowed to float during operation?

No. The EN pin must be actively driven high or low - it must never be left floating. Internal clamping limits EN voltage to ≤12V, and maximum pull-up current must stay below 1mA. For automatic startup, use a resistive divider (e.g., 150kΩ/51kΩ) to set precise UVLO thresholds.

What is the purpose of the AGND pin and how should it be routed?

AGND serves as the reference ground for the internal 0.6V feedback comparator and analog control circuitry. It must be routed separately from PGND and connected to a quiet ground plane near the VFB sensing network to prevent switching noise from degrading regulation accuracy or causing instability.

Does NB669GQ-P support pre-biased output startup?

Yes. If the output is pre-biased at startup, the IC disables both high-side and low-side MOSFETs until the internal reference voltage exceeds the sensed VOUT level at the FB node - preventing reverse current flow and ensuring monotonic voltage ramp-up without output overshoot.