Monolithic Power Systems Inc. NB670AGQ-P

Overview

NB670AGQ-P from Monolithic Power Systems is a fully integrated 5V–24V input, 3.3V fixed-output synchronous buck converter with integrated 3.3V/100mA LDO and 300kHz CLK output, delivering 6A continuous and 9A peak output current in QFN-16 (3mm×3mm) package. It employs Constant-On-Time (COT) control for fast transient response, features internal 30mΩ/15mΩ MOSFETs, and supports laptop power rail generation with power-good signaling and thermal shutdown.

For engineers reviewing the NB670AGQ-P datasheet, NB670AGQ-P pinout, NB670AGQ-P application, or NB670AGQ-P equivalent, key selection considerations include its dual-regulator architecture (buck + LDO), 500kHz switching frequency, integrated OCP/OVP/UVP/fault latching, and dedicated CLK output for external charge pump drive-critical for compact 3.3V system power in space-constrained portable designs.

Technical Context

The NB670AGQ-P implements a COT-controlled synchronous buck topology with valley-current overcurrent protection using low-side R_DS(ON) sensing. Its internal 5V VCC regulator powers control logic, while the 3.3V LDO switches over to VOUT once regulation is established, reducing quiescent loss during operation.

It integrates a 300kHz open-drain CLK output referenced to PGND, designed specifically to drive external charge pump circuits for gate-drive voltage generation. The power-good (PG) signal asserts after 0.5ms delay when VOUT reaches ≥95% of 3.3V and deasserts at ≤85%, with latch-off reset via EN or VIN power cycle.

Key Specifications

Pinout & Package

Package: QFN-16 (3mm × 3mm), exposed thermal pad on underside. Pin 1 marked by dot; pins numbered counterclockwise from top-left corner in top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2451DT-LF-Z and RT7290AZSP, NB670AGQ-P uniquely combines 6A buck, integrated 3.3V LDO with switch-over, and 300kHz CLK in one QFN-16 package-enabling single-chip 3.3V system power with gate-drive support, where alternatives require additional ICs or sacrifice current capability.

Availability

NB670AGQ-P is available at Aetrix Electronics and suitable for laptop computer power rails, tablet PC core logic supplies, and flat-panel display logic boards requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for NB670AGQ-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.

NB670AGQ-P belongs to MPS's high-current DC/DC converter product line, designed specifically for compact, efficient 3.3V system power in portable computing and consumer display applications where integration, thermal performance, and multi-rail support are critical.

FAQ

What is the purpose of the CLK pin on NB670AGQ-P?

The CLK pin outputs a 300kHz square wave referenced to PGND, intended to drive an external charge pump circuit. This generates ~12–15V gate-drive voltage for external load switches or high-side FETs without drawing current from the main buck converter, preserving its efficiency and thermal margin.

How does the LDO switch-over function work?

Once the main buck output (VOUT) reaches ≥3.15V and the power-good flag asserts, the internal 3.3V LDO shuts off and an internal MOSFET connects the LDO output pin directly to VOUT. This switch-over reduces quiescent power loss during normal operation while retaining 100mA auxiliary capability during startup or fault conditions.

Can NB670AGQ-P operate with ceramic output capacitors only?

Yes. Unlike traditional COT controllers, NB670AGQ-P includes internal ramp compensation that ensures stability with zero-ESR ceramic capacitors. This eliminates the need for electrolytic or high-ESR tantalum capacitors, reducing board area, cost, and output ripple.

What triggers latch-off protection and how is it reset?

Latch-off is triggered by overvoltage (OVP ≥130%), undervoltage (UVP ≤60%), overcurrent (valley-current limit exceeded), or thermal shutdown (T_J ≥150°C). It disables the high-side FET and holds the low-side FET on until inductor current decays to zero. Reset occurs only by pulling EN low or cycling VIN power.

Is NB670AGQ-P suitable for new designs despite the "NOT RECOMMENDED" notice?

No. The "NOT RECOMMENDED FOR NEW DESIGNS" designation indicates MPS has superseded NB670AGQ-P with newer-generation parts (e.g., MPQ4420 series) offering improved efficiency, smaller packages, or enhanced protection. Aetrix recommends evaluating MPQ4420A-AEC1 or MPQ4470 for new designs requiring similar specs.

What is the role of AGND versus PGND in layout?

AGND is the analog reference ground for the feedback comparator and internal VREF; it must be routed separately from PGND (high-current power ground) and connected to the PGND plane at a single point near the IC to prevent noise coupling into the regulation loop. Mixing them degrades load/line regulation accuracy.

Does NB670AGQ-P support pre-biased output start-up?

Yes. During start-up, if VOUT is pre-biased above the internal FB node voltage, the NB670AGQ-P disables both high-side and low-side FETs until the internal reference ramps above the sensed output voltage. This prevents reverse current flow and ensures controlled, glitch-free power-on sequencing.