Monolithic Power Systems Inc. NB670GQ-P

Overview

NB670GQ-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 / 9A peak current in QFN-16 (3mm×3mm) package. It employs Constant-On-Time (COT) control for fast transient response, features internal 30mΩ/15mΩ MOSFETs, and targets high-density power rails in laptop and tablet mainboard applications.

For engineers reviewing the NB670GQ-P datasheet, NB670GQ-P pinout, NB670GQ-P application, or NB670GQ-P equivalent, key selection criteria include its dual-regulator architecture (buck + LDO), 500kHz switching frequency, PG open-drain signal timing (0.5ms delay), and EN/ENLDO dual-enable logic for sequenced power-up in portable systems.

Technical Context

The NB670GQ-P integrates a COT-controlled synchronous buck stage with valley-current OCP, internal 5V VCC LDO, and a dedicated 3.3V LDO with switch-over functionality that connects to VOUT once output reaches 3.15V. Its block diagram confirms independent control paths for buck regulation, LDO enable, and CLK generation - all synchronized to VIN and AGND references.

Operation includes automatic transition between PWM (CCM) and skip-mode (DCM) based on load, with internal ramp compensation enabling stable ceramic-capacitor-only output filtering. Protection logic implements latch-off reset via EN low or VIN power cycle, not auto-recovery.

Key Specifications

Pinout & Package

Package: QFN-16 (3mm × 3mm), exposed thermal pad on underside. Pin 1 marked by dot; pins 8/9/15/16 are exposed pad connections tied to PGND internally.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck converter with integrated LDO applications.

Compared with MP2451DT-LF-Z and RT7290AZSP, NB670GQ-P uniquely integrates CLK generation and LDO switch-over, enabling single-chip solutions for portable systems requiring coordinated power sequencing, gate drive support, and standby rail optimization - at the trade-off of higher pin count and QFN-16 footprint.

Availability

NB670GQ-P is available at Aetrix Electronics and suitable for laptop computer, tablet PC, and flat panel television applications requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant packaging.

Supply support for NB670GQ-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 power ICs, with over 20 years of expertise in DC-DC conversion and power management.

NB670GQ-P belongs to MPS's high-current integrated buck converter product line, designed specifically for space-constrained portable computing platforms requiring multi-rail power with minimal external components and robust protection.

FAQ

What is the purpose of the dual-enable pins EN and ENLDO?

EN controls only the buck regulator and CLK output, while ENLDO enables or disables the entire IC including VCC and the 3.3V LDO. When ENLDO is low, all regulators shut down - this allows full-system power gating. EN must not be left floating and should be driven by a logic signal or resistive divider per datasheet Table 1.

How does the LDO switch-over function work?

The internal 3.3V LDO powers external circuitry during startup. Once VOUT reaches 3.15V and PG asserts, an internal MOSFET connects LDO output to VOUT, disabling the LDO to reduce quiescent loss. This switch-over is deglitched with 20µs filtering to prevent glitches during transient conditions.

Can NB670GQ-P operate with ceramic-only output capacitors?

Yes - unlike traditional COT converters, NB670GQ-P includes internal ramp compensation that ensures stability with low-ESR ceramic capacitors. No additional ESR is required, enabling smaller footprint, lower ripple, and reduced BOM cost versus electrolytic+ceramic hybrid solutions.

What is the role of the CLK output beyond driving charge pumps?

The 300kHz CLK is a buffered, rail-to-rail square wave intended solely for external charge pump circuits generating gate drive voltages. It is not intended for clock distribution, timing reference, or synchronization with other ICs - its jitter and phase accuracy are not specified for such uses.

Why does NB670GQ-P specify "NOT RECOMMENDED FOR NEW DESIGNS"?

This designation indicates MPS has superseded NB670GQ-P with newer-generation parts offering improved efficiency, smaller packages, or enhanced protection. However, NB670GQ-P remains fully qualified, in production, and supported with full documentation - suitable for legacy design refresh, repair, or cost-sensitive volume programs where redesign is not feasible.

How is thermal performance affected by the exposed pad connection?

The exposed pad (pins 8/9/15/16) must be soldered to a solid PGND copper plane with ≥4 thermal vias to achieve the specified θJA of 70°C/W. Inadequate pad connection increases junction temperature by up to 40°C at 6A load, potentially triggering thermal shutdown prematurely.

Does NB670GQ-P support pre-biased output startup?

Yes - if VOUT is pre-biased above the internal reference voltage at startup, the IC disables both high-side and low-side switches until the internal soft-start reference exceeds the sensed FB voltage. This prevents reverse current flow and ensures controlled ramp-up even with hot-plug or battery-backed outputs.