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Monolithic Power Systems Inc. NB671LGQ-P
- Part No.:
- NB671LGQ-P
- Manufacturer:
- Monolithic Power Systems Inc.
- Package:
- 16-PowerVFQFN
- Datasheet:
-
NB671LGQ-P.pdf
- Description:
- IC REG BUCK ADJ 6A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,908
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Product details
Overview
NB671LGQ-P from Monolithic Power Systems is a high-efficiency, 5.5V–24V input synchronous step-down DC/DC converter delivering 6A continuous and 9A peak output current with 120μA quiescent current. It employs Constant-On-Time (COT) control for fast transient response, integrates low-RDS(ON) MOSFETs (30mΩ HS / 15mΩ LS), and supports adjustable output from 0.604V to 5.5V - used in laptop power rails and flat-panel display logic supplies.
For engineers reviewing the NB671LGQ-P datasheet, NB671LGQ-P pinout, NB671LGQ-P application, or NB671LGQ-P equivalent, key selection criteria include its LP#-enabled low-power mode (60μA IQ), internal soft-start, output discharge capability, 500kHz switching frequency (with adaptive reduction down to ~150kHz at 5.5VIN/5VOUT), and integrated OCP/OVP/UVP/thermal shutdown with latch-off reset.
Technical Context
The NB671LGQ-P implements a proprietary COT control architecture with internal ramp compensation, enabling stable operation with ceramic output capacitors without external compensation. Its valley-current OCP senses via low-side MOSFET RDS(ON), triggering cycle-by-cycle limiting at 7.8–9.5A.
It features dual-mode operation: PWM (CCM) at heavy loads with fixed-frequency regulation, and skip-mode (DCM) at light loads where LS-FET driver enters high-Z state and current modulation limits reverse inductor current to <−1mA - reducing switching losses and achieving high light-load efficiency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 24V - supports wide industrial and computing input rails including 12V, 19V, and 24V systems. |
| Output Current | 6A continuous / 9A peak - enables single-chip power delivery for CPU I/O, GPU core, or display interface rails. |
| Quiescent Current | 120μA (typ.) - ensures >85% efficiency at 1mA load; drops to 60μA in LP#-activated low-power mode. |
| Switching Frequency | 400–600kHz (typ. 500kHz) - balances EMI, inductor size, and efficiency; reduces to ~150kHz at 5.5VIN/5VOUT for high duty-cycle operation. |
| Reference Voltage | 604mV ±6mV - sets output accuracy; enables precise 1% VOUT regulation via external resistor divider. |
| Protection Features | OCP (valley-current limit), OVP (130% VREF latch), UVP (60% VREF latch), thermal shutdown (150°C), and UVLO (4.76V VCC threshold). |
| Power Good Signal | Open-drain PG with 95%/85% VREF thresholds and 0.5ms delay - provides reliable system power sequencing and fault indication. |
Pinout & Package
Package: QFN16 (3mm × 3mm, exposed thermal pad). Pin count: 16 terminals (including 2 NC pins and 2 SW pins paralleled internally).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VIN | Primary input supply | Accepts 5.5–24V; requires local bulk decoupling; connects directly to high-side MOSFET source and internal LDO input. |
| 2 PGND | Power ground return | Low-impedance path for high di/dt switch currents; must be tied to exposed pad and connected via multiple vias. |
| 3 LP# | Low-power mode enable | Active-low logic input (0.45V low / 0.67V high); reduces IQ to 60μA when asserted; 3.3V-tolerant. |
| 4 PG | Power good open-drain output | Indicates VOUT ≥95% VREF; requires external pull-up; sinks 4mA at 0.4V for fault signaling. |
| 5,6 NC | No connect | Unbonded; must remain unconnected per datasheet - no routing or stitching allowed. |
| 7 VOUT | Output voltage sense | Direct connection point to output capacitor; used for feedback loop stability and remote sensing. |
| 8,9 Exposed Pad | Thermal & ground plane | Internally connected to PGND; mandatory for thermal dissipation (θJA = 70°C/W) and EMI reduction. |
| 10 BST | Bootstrap supply | Connects to SW via 0.1μF ceramic capacitor; forms floating gate drive for high-side MOSFET. |
| 11 VCC | Internal 5V LDO output | Powers control circuitry; requires ≥1μF X7R/X5R ceramic decoupling placed within 2mm of pin. |
| 12 FB | Feedback input | Resistor divider tap point; referenced to AGND; high-impedance (10–50nA) for precision VOUT setting. |
| 13 EN | Enable control | Digital input (1.15–1.4V threshold); pulls up to VIN for automatic startup; latches off during faults. |
| 14 AGND | Analog ground reference | Separate from PGND; ties internal reference and FB divider ground - critical for <1% output regulation. |
| 15,16 SW | Switch node | Paralleled high-current output; drives external inductor and BST capacitor; swings from −0.3V to VIN+4V. |
Key Features
| Feature | Design Value |
|---|---|
| Proprietary switching loss reduction | Optimizes dead-time and gate drive timing to minimize shoot-through and conduction loss across load range. |
| Internal soft start | 1.8ms monotonic VREF ramp prevents inrush current and output overshoot during power-up. |
| Output discharge function | Integrated 6Ω NMOS between VOUT and PGND actively discharges output when disabled or faulted - avoids residual voltage hold-up. |
| Adaptive COT with internal ramp | Eliminates need for external ramp components; stabilizes control loop with ceramic-only output capacitors (no ESR dependency). |
| LP#-controlled ultra-low IQ mode | Reduces quiescent current from 120μA to 60μA while maintaining regulation - extends battery runtime in standby states. |
Applications
| Laptop Mainboard VRM | Tablet SoC Core Supply |
|---|---|
|
Use Scenario: Powers Intel Core i-series or AMD Ryzen mobile CPU I/O rail (1.05V/3A) from 12V or 19V adapter input. IC Role / Device Role / Timing Role: Primary synchronous buck regulator with fast transient response to handle CPU burst loads (e.g., Turbo Boost). Use Value: 6A continuous rating and COT control ensure <50mV output deviation during 3A/μs load steps; LP# mode cuts idle power by 50%. |
Use Scenario: Supplies ARM-based application processor core voltage (0.8V/4A) in battery-powered tablets using 3.7–4.2V Li-ion input. IC Role / Device Role / Timing Role: High-efficiency step-down converter operating in skip-mode at light loads and PWM at active loads. Use Value: 120μA IQ and 60μA LP# mode extend battery life >12 hours in standby; 500kHz switching minimizes inductor size (<2.2μH). |
| Flat Panel Display Logic Rail | Distributed Telecom Power |
|
Use Scenario: Generates 3.3V/5A logic supply for LCD controller and timing controller (TCON) in 24V-powered monitors. IC Role / Device Role / Timing Role: Compact, thermally efficient DC/DC stage replacing discrete solutions in space-constrained front bezel PCBs. Use Value: QFN16 (3×3mm) package and integrated MOSFETs reduce BOM count by 7 parts; PG signal enables display power sequencing. |
Use Scenario: Provides isolated 5V/6A intermediate bus for PoE-powered access points or small-cell baseband modules fed from 24V backplane. IC Role / Device Role / Timing Role: High-current intermediate converter with robust protection for unattended telecom equipment. Use Value: Latch-off OVP/UVP and thermal shutdown prevent field failures; 9A peak supports inrush of downstream hot-swap controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2451DT-LF-Z | 4.75–36V input, 0.8A max, no LP# pin, higher IQ (250μA), no output discharge. | Suitable only for sub-1A loads; lacks low-power mode and discharge - not drop-in for NB671LGQ-P's 6A/low-IQ use cases. | Select only if output current ≤0.8A and LP#/discharge are unnecessary. |
| RT7297CGJ8 | 4.5–24V input, 6A continuous, 150μA IQ, no LP# pin, no integrated discharge MOSFET. | Matches current rating but lacks LP#-enabled ultra-low IQ and active output discharge - compromises battery standby time and safety. | Prefer NB671LGQ-P where <60μA IQ or controlled discharge is required; RT7297CGJ8 fits cost-sensitive 6A designs without those features. |
Compared with MP2451DT-LF-Z and RT7297CGJ8, NB671LGQ-P uniquely combines 6A capability, 60μA LP#-mode IQ, and integrated output discharge - making it irreplaceable for high-current, battery-sensitive applications requiring both performance and safety.
Availability
NB671LGQ-P is available at Aetrix Electronics and suitable for laptop mainboards, tablet SoC power rails, flat-panel display logic supplies, and distributed telecom power systems requiring stable component supply throughout design-in, prototyping, and volume production.
Supply support for NB671LGQ-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 leadership in DC/DC conversion, motor drivers, and LED lighting controllers.
NB671LGQ-P belongs to MPS's NB67x family of high-current, low-quiescent-current synchronous buck converters - designed specifically for portable computing and display power where efficiency, thermal density, and feature integration are critical.
FAQ
What is the function of the LP# pin, and how does it affect efficiency?
The LP# (Low Power) pin is an active-low input that enables ultra-low quiescent current mode. When pulled low, it reduces IQ from 120μA to 60μA, significantly improving light-load efficiency in battery-powered standby states. The pin is 3.3V-tolerant and supports 1.05V logic levels; if unused, it must be pulled to VCC via a >1MΩ resistor to avoid floating.
Can NB671LGQ-P operate with a 5.5V input and 5V output?
Yes - NB671LGQ-P supports 5.5VIN/5VOUT conversion using its adaptive COT control. At this near-unity ratio, switching frequency drops to ~150kHz to maintain stable regulation and minimize ripple, enabled by internal ramp compensation and optimized dead-time control.
Does NB671LGQ-P require external compensation components?
No - NB671LGQ-P includes internal ramp compensation, allowing stable operation with ceramic-only output capacitors (no ESR dependency). External ramp components (R/C network) are optional and only needed in edge-case layouts with extreme parasitics or marginal phase margin.
How does the output discharge function work, and what is its on-resistance?
When EN is low or a fault triggers shutdown, NB671LGQ-P activates an internal 6Ω NMOS between VOUT and PGND to safely discharge the output capacitor. This prevents residual voltage from interfering with system reset or causing latch-up in downstream logic - no external FET or resistor is required.
What is the maximum recommended PCB copper area for thermal relief on the exposed pad?
The QFN16 (3×3mm) exposed pad must be connected to a minimum 100mm² solid PGND copper pour with ≥6 thermal vias (0.3mm diameter, spaced ≤1mm apart) to achieve the specified θJA = 70°C/W. Reducing copper area or via count increases junction temperature and risks thermal shutdown under 6A load.
Is NB671LGQ-P pin-compatible with NB671, and what is the key pin difference?
Yes - NB671LGQ-P is pin-to-pin compatible with NB671, except pin 3: NB671 uses NC (no connect), while NB671LGQ-P repurposes it as LP#. All other pins (VIN, PGND, PG, SW, BST, VCC, FB, EN, AGND, VOUT) retain identical functions and locations.
What protection mechanisms trigger latch-off versus auto-recovery behavior?
OVP (130% VREF) and UVP (60% VREF) cause latch-off shutdown; recovery requires EN toggling low or full VIN power cycle. Thermal shutdown and UVLO are auto-recovering - operation resumes once junction temperature falls below 125°C or VIN rises above 4.76V.
NB671LGQ-P Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Monolithic Power Systems Inc.
- Series:
- -
- Package/Case:
- 16-PowerVFQFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5.5V
- Voltage - Input (Max):
- 22V
- Voltage - Output (Min/Fixed):
- 0.604V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 6A
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
NB671LGQ-P FAQ
1.How can I place an order for NB671LGQ-P through Aetrix?
Please submit a Request for Quotation (RFQ) for NB671LGQ-P on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for NB671LGQ-P reliable?
The price and inventory of NB671LGQ-P are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NB671LGQ-P is usually 5 days.
3.What payment methods are accepted for NB671LGQ-P?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NB671LGQ-P transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for NB671LGQ-P?
NB671LGQ-P orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your NB671LGQ-P order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for NB671LGQ-P?
For technical support, including NB671LGQ-P datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NB671LGQ-P requirements.
6.How does Aetrix verify that NB671LGQ-P is sourced from the original manufacturer or authorized distributors?
All NB671LGQ-P products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that NB671LGQ-P meets industry standards.
7.What is the process for return or replacement of NB671LGQ-P?
All NB671LGQ-P units undergo pre-shipment inspection (PSI). If there is an issue with NB671LGQ-P, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The NB671LGQ-P part is unused and in its original packaging.
Return procedure for NB671LGQ-P:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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