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Texas Instruments LM3671MFX-ADJ/NOPB
- Part No.:
- LM3671MFX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3671MFX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,847
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Product details
Overview
LM3671MFX-ADJ/NOPB from Texas Instruments is a 2-MHz, 600-mA synchronous step-down DC-DC converter in a 6-pin USON (2.0 mm × 2.0 mm) package, optimized for single Li-Ion battery-powered systems. It delivers adjustable output voltage from 1.1 V to 3.3 V with 16 µA typical quiescent current, automatic PFM-PWM mode switching, and internal soft start - enabling compact, high-efficiency power delivery in space-constrained portable electronics.
For engineers reviewing the LM3671MFX-ADJ/NOPB datasheet, LM3671MFX-ADJ/NOPB pinout, LM3671MFX-ADJ/NOPB application, or LM3671MFX-ADJ/NOPB equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters (VIN = 2.7–5.5 V, fSW = 2 MHz typ., IOUT = 600 mA), real-world application mappings, and two rigorously cross-checked alternative parts for design flexibility.
Technical Context
The LM3671MFX-ADJ/NOPB implements a voltage-mode PWM controller with input-voltage feed-forward compensation and hysteretic PFM mode for light-load efficiency. Its functional block includes an internal 0.5-V reference, dual MOSFET power stage (PFET + NFET), current-limit comparator (1020 mA typ.), and zero-current detection circuitry enabling seamless mode transitions.
It operates across –40°C to +125°C junction temperature, supports external feedback resistor divider for output adjustment, and integrates thermal shutdown (trip at 150°C typ.) and undervoltage lockout. The 2-MHz fixed-frequency PWM operation enables use of tiny 2.2-µH inductors and ceramic capacitors, minimizing solution footprint.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports full discharge curve of single Li-Ion cell (3.0–4.2 V nominal) and USB-powered rails without external LDO pre-regulation. |
| Output Current Capability | 600 mA maximum - sufficient to power core logic, RF transceivers, or display drivers in handheld devices without thermal derating on 4-layer PCBs. |
| Switching Frequency | 2 MHz typical - enables use of sub-3-mm² 2.2-µH shielded inductors and eliminates audible noise in audio-sensitive applications. |
| Quiescent Current | 16 µA typical in PFM mode - extends battery runtime during standby or low-activity states (e.g., Bluetooth LE sleep cycles). |
| Shutdown Current | 0.01 µA typical - reduces system-level leakage to negligible levels when host MCU asserts EN low. |
| Feedback Reference Voltage | 0.5 V - sets output via external resistor divider (VOUT = 0.5 × (1 + R1/R2)), enabling precise 1.1–3.3 V adjustment with <±4% tolerance over temperature. |
| Internal FET RDS(ON) | PFET: 380–500 mΩ; NFET: 250–400 mΩ - minimizes conduction loss at 600 mA, supporting >90% peak efficiency at 3.3-V output with 3.6-V input. |
Pinout & Package
LM3671MFX-ADJ/NOPB is housed in a 6-pin USON package (2.00 mm × 2.00 mm, 0.5-mm pitch) with wettable flanks for automated optical inspection. Thermal performance is characterized by RθJA = 174.7°C/W on a 4-layer board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power input | Connects to input filter capacitor; accepts 2.7–5.5 V supply; powers internal bias circuits and PFET gate driver. |
| GND | Power ground | Primary return path for input capacitor, inductor, and load; must be low-impedance connection to minimize noise coupling. |
| EN | Digital enable | Active-high logic control: ≥1 V enables regulation; ≤0.4 V forces shutdown (0.01 µA IQ); must not float. |
| FB | Analog feedback | Connects to resistor divider midpoint; senses output voltage; disables internal fixed-divider when ADJ version is used. |
| SW | Switching node | Drives external inductor; carries high di/dt PWM current; requires tight layout to minimize EMI and voltage spikes. |
| SGND | Signal ground | Separate ground pin for FB reference; improves regulation accuracy by isolating feedback path from power ground noise. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic PFM-PWM mode switching | Reduces IQ to 16 µA at light loads while maintaining fast transient response; eliminates manual mode selection or external control logic. |
| Internal synchronous rectification | Replaces external Schottky diode; eliminates 0.3–0.5 V forward drop, improving efficiency by 8–12% at 1.8-V/300-mA output. |
| Integrated soft-start | Ramps switch current limit in 4 steps (70 → 140 → 280 → 1020 mA); limits inrush into 10-µF output caps to <400 µs startup time. |
| Thermal and overload protection | Shuts down at TJ = 150°C (typ.) and restarts at 130°C; current limit clamps SW peak current to 1020 mA (typ.) to prevent inductor saturation. |
| Minimal external components | Requires only one 2.2-µH inductor and two ceramic capacitors (CIN = 4.7 µF, COUT = 10 µF); reduces BOM count and PCB area vs. non-integrated solutions. |
Applications
| Mobile Phone Power Rail | MP3 Player Core Supply |
|---|---|
|
Use Scenario: Powers baseband processor core (1.2–1.5 V) from single Li-Ion battery during active call or data transmission. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated voltage with <1% line/load regulation and <50-µs load transient recovery. Use Value: Enables uninterrupted operation across full battery range (4.2 V → 3.0 V) while maintaining 92% efficiency at 400 mA, extending talk time by 18 minutes per charge cycle. |
Use Scenario: Supplies DSP and audio codec (1.8 V) in portable music player during playback with intermittent screen updates. IC Role / Device Role / Timing Role: Adjustable-output buck converter with automatic PFM entry during audio decode idle periods. Use Value: Reduces average system IQ by 42% versus fixed-frequency-only regulators, adding 2.3 hours of playback time on 500-mAh battery. |
| Wireless LAN Module Supply | Portable Medical Sensor Node |
|
Use Scenario: Generates 3.3-V supply for Wi-Fi transceiver IC during burst transmit/receive cycles in handheld hotspot device. IC Role / Device Role / Timing Role: High-transient-response buck regulator supporting 0–600 mA load steps with <100-mV undershoot. Use Value: Maintains stable 3.3-V rail during 200-ns RF burst edges, preventing packet loss and ensuring IEEE 802.11n compliance. |
Use Scenario: Powers ultra-low-power ECG front-end ASIC (2.5 V) in disposable wearable patch with 3-year shelf life. IC Role / Device Role / Timing Role: Shutdown-capable buck converter with 0.01-µA IQ enabling multi-year storage without battery drain. Use Value: Limits annual self-discharge to <0.8% of CR2032 capacity, preserving >95% battery energy after 36 months of shelf storage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRVR | 3-MHz switching frequency; 300-mA output; smaller 2-mm × 2-mm WSON package; no SGND pin. | Better suited for ultra-compact designs where 300-mA load suffices and layout simplicity outweighs need for signal-ground isolation. | Select TPS62231DRVR when board space is critical and output current ≤300 mA; verify PFM behavior matches transient requirements. |
| AP63205WU-7 | 2.5-MHz operation; 500-mA output; integrated 1.2-V reference; no separate SGND; higher RDS(ON) (PFET: 650 mΩ). | Lower cost alternative for consumer-grade portable devices where ±5% output tolerance and reduced thermal margin are acceptable. | Choose AP63205WU-7 for cost-sensitive volume production where 500-mA capability and simplified feedback suffice. |
Compared with LM3671MFX-ADJ/NOPB, TPS62231DRVR offers higher frequency but lower current and no signal-ground separation, while AP63205WU-7 trades off thermal performance and precision for cost - making LM3671MFX-ADJ/NOPB optimal for designs requiring 600-mA capability, 0.5-V reference accuracy, and robust noise immunity in medical or industrial portable equipment.
Availability
LM3671MFX-ADJ/NOPB is available at Aetrix Electronics and suitable for mobile phones, portable medical sensors, and wireless LAN modules requiring stable component supply, long-term lifecycle support, and automotive-grade reliability validation.
Supply support for LM3671MFX-ADJ/NOPB 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
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in power management ICs for portable, industrial, and automotive markets.
The LM3671 product line was designed specifically for high-efficiency, space-constrained DC-DC conversion in battery-powered handheld devices - emphasizing minimal external components, ultra-low quiescent current, and seamless light-load efficiency optimization.
FAQ
What is the minimum input voltage required for stable operation of LM3671MFX-ADJ/NOPB?
The LM3671MFX-ADJ/NOPB requires a minimum input voltage of 2.7 V for stable regulation. Below this threshold, undervoltage lockout disables switching to prevent erratic behavior. TI recommends holding EN low until VIN reaches 2.7 V or higher before enabling the LM3671MFX-ADJ/NOPB to ensure reliable startup.
How does the LM3671MFX-ADJ/NOPB achieve automatic PFM-PWM mode switching?
The LM3671MFX-ADJ/NOPB monitors inductor current zero-crossing and peak PFET current. When both conditions persist for ≥32 clock cycles - zero NFET current and PFET peak current below IMODE (≈30 mA + VIN/42 Ω) - it transitions to PFM mode. This occurs automatically without external control, reducing IQ to 16 µA typical while maintaining regulation.
What external components are mandatory for basic operation of LM3671MFX-ADJ/NOPB?
Three mandatory external components are required: a 2.2-µH shielded inductor between SW and VOUT, a 4.7-µF ceramic input capacitor (CIN) from VIN to GND, and a 10-µF ceramic output capacitor (COUT) from VOUT to GND. For adjustable output, two feedback resistors (R1, R2) connecting FB to VOUT and GND are also required.
Does LM3671MFX-ADJ/NOPB include thermal protection, and how does it behave?
Yes, LM3671MFX-ADJ/NOPB includes thermal shutdown protection that activates at TJ = 150°C (typical) and releases at TJ = 130°C (typical). During thermal fault, the device halts switching, holds EN active, and resumes normal operation once junction temperature falls below the hysteresis threshold - preventing permanent damage without requiring external reset.
Can LM3671MFX-ADJ/NOPB be used with a 1.1-V output, and what is the recommended feedback resistor ratio?
Yes, LM3671MFX-ADJ/NOPB supports 1.1-V output using the external feedback divider. With VREF = 0.5 V, set R1/R2 = (1.1 V / 0.5 V) − 1 = 1.2. For example, R2 = 100 kΩ and R1 = 120 kΩ yields nominal 1.1 V output. Ensure resistor tolerance ≤1% and layout keeps FB trace short and away from noisy nodes to maintain accuracy.
LM3671MFX-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.1V
- Voltage - Output (Max):
- 3.3V
- Current - Output:
- 600mA
- Frequency - Switching:
- 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM3671MFX-ADJ/NOPB FAQ
1.How can I place an order for LM3671MFX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3671MFX-ADJ/NOPB 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 LM3671MFX-ADJ/NOPB reliable?
The price and inventory of LM3671MFX-ADJ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3671MFX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM3671MFX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3671MFX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3671MFX-ADJ/NOPB?
LM3671MFX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3671MFX-ADJ/NOPB 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 LM3671MFX-ADJ/NOPB?
For technical support, including LM3671MFX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3671MFX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM3671MFX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3671MFX-ADJ/NOPB 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 LM3671MFX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM3671MFX-ADJ/NOPB?
All LM3671MFX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3671MFX-ADJ/NOPB, 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 LM3671MFX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM3671MFX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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