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Texas Instruments LM3671MFX-1.8/NOPB
- Part No.:
- LM3671MFX-1.8/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3671MFX-1.8/NOPB.pdf
- Description:
- IC REG BUCK 1.8V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:11,060
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Product details
Overview
LM3671MFX-1.8/NOPB from Texas Instruments is a fixed-output 1.8 V, 600-mA synchronous step-down DC-DC converter optimized for single Li-Ion battery systems (2.7 V–5.5 V input). It delivers regulated power with 2-MHz PWM switching, 16-µA quiescent current in PFM mode, and internal soft-start-enabling compact, high-efficiency power rails in space-constrained portable electronics.
For engineers reviewing the LM3671MFX-1.8/NOPB datasheet, LM3671MFX-1.8/NOPB pinout, LM3671MFX-1.8/NOPB application, or LM3671MFX-1.8/NOPB equivalent, key selection criteria include output voltage accuracy (±4% over −40°C to +125°C), shutdown current (0.01 µA typical), thermal shutdown at 150°C, and compatibility with only three external components: one 2.2-µH inductor and two ceramic capacitors.
Technical Context
The LM3671MFX-1.8/NOPB implements voltage-mode control with input feed-forward compensation to maintain stable regulation across line and load variations. Its integrated PFET/NFET synchronous rectifier eliminates external diode losses, enabling >90% efficiency at moderate loads while supporting automatic transition between 2-MHz PWM (for low-noise operation) and hysteretic PFM (for ultra-low IQ at light loads).
Functional modes are governed by real-time inductor current sensing: PWM dominates above ~80 mA load; PFM engages below that threshold to reduce quiescent current to 16 µA; and shutdown disables switching entirely, drawing just 0.01 µA. Internal 0.5-V reference and fixed feedback divider set VOUT = 1.8 V without external resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.8 V ±4% over −40°C to +125°C - eliminates need for external feedback resistors and simplifies layout. |
| Max Output Current | 600 mA continuous - supports core logic, memory, and RF ICs in handheld devices without thermal derating under typical conditions. |
| Input Voltage Range | 2.7 V to 5.5 V - compatible with single-cell Li-ion (fully charged to 4.2 V, discharged to 2.7 V) and 3.3-V/5-V rails. |
| Switching Frequency | 2 MHz (typical, PWM mode) - enables use of tiny 2.2-µH inductors and 10-µF ceramic output capacitors for minimal board area. |
| Quiescent Current | 16 µA (typical, PFM mode) - extends battery life in standby/sleep states of portable instruments and wearables. |
| Shutdown Current | 0.01 µA (typical) - ensures negligible battery drain during system off-state, critical for always-on sensors and remote controls. |
| Internal Reference | 0.5 V - sets feedback threshold; combined with fixed resistor divider, defines precise 1.8-V output without calibration. |
Pinout & Package
LM3671MFX-1.8/NOPB uses the 6-pin USON (NKH) package: 2.00 mm × 2.00 mm body, 0.5-mm pitch, wettable flank terminals for automated optical inspection. Thermal resistance RθJA = 174.7°C/W (4-layer board).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power input | Accepts 2.7–5.5 V; requires local 4.7-µF ceramic decoupling capacitor to minimize input ripple and ESR-related losses. |
| SW | Switching node | Connects internally to PFET drain and NFET source; drives external 2.2-µH inductor; must be routed with minimal loop area to reduce EMI. |
| FB | Feedback input | Internally connected to fixed resistor divider for 1.8-V regulation; no external components required - simplifies BOM and layout. |
| EN | Enable control | Digital input: <0.4 V = shutdown (0.01 µA IQ), >1 V = active; must not float - tie to VIN or microcontroller GPIO. |
| GND | Power ground | Primary return path for input/output currents; requires low-impedance connection to PCB ground plane beneath the USON pad. |
| SGND | Signal ground | Separate analog ground pin for FB reference; connects internally to GND but should be star-connected near FB pin to avoid noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated PFET/NFET replaces external Schottky diode - reduces conduction loss and improves full-load efficiency by up to 12% vs. asynchronous designs. |
| Auto PFM-PWM mode switching | Seamless transition at ~80 mA load - maintains >85% efficiency from 1 mA to 600 mA without manual mode control or external circuitry. |
| Internal soft-start | Staged current limit ramp (70 → 140 → 280 → 1020 mA) - prevents inrush current spikes into 10-µF output caps, enabling reliable startup with 300-mA loads in ≤400 µs. |
| Thermal & overload protection | Automatic shutdown at TJ = 150°C (typ.) and cycle-by-cycle current limiting at 1020 mA (open-loop) - protects IC and PCB during fault conditions. |
| Ultra-low shutdown current | 0.01 µA typical - draws less than 1 µA per year from a 100-mAh coin cell, enabling decade-scale shelf life in IoT endpoint applications. |
Applications
| Mobile Phone Power Rail | Wireless Audio Codec Supply |
|---|---|
|
Use Scenario: Powers baseband processor I/O and memory interface in GSM/UMTS smartphones operating from single Li-Ion cell. IC Role / Device Role / Timing Role: Primary 1.8-V buck regulator delivering clean, low-noise supply with fast transient response to handle burst-mode RF transmission. Use Value: 2-MHz switching avoids AM radio band interference; 16-µA PFM IQ extends talk time by >15% versus 500-kHz alternatives with same output cap. |
Use Scenario: Supplies 1.8-V digital core voltage to Bluetooth audio SoC in true wireless stereo earbuds. IC Role / Device Role / Timing Role: Compact, low-quiescent DC-DC converter enabling 30-hour playback on 50-mAh battery with minimal PCB footprint. Use Value: USON package (2 mm × 2 mm) fits within 8-mm earbud cavity; 0.01-µA shutdown current prevents battery drain during multi-week storage. |
| Digital Still Camera Sensor Bias | Automotive Infotainment Display Logic |
|
Use Scenario: Provides stable 1.8-V supply to CMOS image sensor and ISP in compact point-and-shoot cameras. IC Role / Device Role / Timing Role: Fixed-output buck converter with tight load regulation (0.0013%/mA) ensuring consistent ADC reference and pixel timing. Use Value: Load regulation spec guarantees <1 mV output shift from 10 mA to 600 mA - prevents image noise and color banding during video capture. |
Use Scenario: Generates 1.8-V logic rail for display controller and touch interface in automotive-grade head units. IC Role / Device Role / Timing Role: AEC-Q100 Grade 1 qualified variant (LM3671-Q1) supports −40°C to +125°C ambient operation. Use Value: Thermal shutdown at 150°C prevents latch-up in sealed enclosures; 2.7–5.5 V input range accommodates vehicle battery transients (load dump, cold crank). |
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 |
|---|---|---|---|
| TPS62231DRYR | Fixed 1.8 V, 600-mA, 3-MHz switching, 19-µA IQ (PFM), SOT-23-5 package | Higher switching frequency enables smaller inductor (1.0 µH), but lacks SGND pin and has higher RDS(ON) (PFET: 550 mΩ) | Prefer when board space is constrained and 3-MHz EMI profile is acceptable; avoid if signal-ground separation is critical for noise-sensitive analog circuits. |
| AP63202WU-7 | Fixed 1.8 V, 2-A, 2.2-MHz, 25-µA IQ, WLCSP-6 package (1.5 mm × 1.5 mm) | Higher current rating and smaller footprint, but requires external compensation and has no integrated soft-start | Choose for future-proofing against load growth or ultra-miniaturized designs; accept added design complexity for 2× current headroom. |
Compared with TPS62231DRYR and AP63202WU-7, the LM3671MFX-1.8/NOPB offers superior noise performance due to its dedicated SGND pin and proven PFM-PWM transition stability, making it optimal for mixed-signal portable systems where analog integrity and predictable light-load behavior are prioritized over raw current capacity or minimum size.
Availability
LM3671MFX-1.8/NOPB is available at Aetrix Electronics and suitable for mobile phones, wireless audio devices, and digital still cameras requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for LM3671MFX-1.8/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 designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and consumer markets since 1930.
The LM3671 product line targets ultra-compact, battery-optimized DC-DC conversion in portable electronics - emphasizing minimal external component count, sub-20-µA quiescent operation, and robust protection features for unattended operation.
FAQ
What is the recommended input capacitor for LM3671MFX-1.8/NOPB?
The LM3671MFX-1.8/NOPB datasheet specifies a 4.7-µF X5R/X7R ceramic capacitor at the VIN pin. This value ensures sufficient charge reservoir for 2-MHz switching transients and maintains input voltage stability under 600-mA load steps. Place it within 3 mm of the VIN and GND pins using short, wide traces to minimize ESL and prevent oscillation. The LM3671MFX-1.8/NOPB will not meet ripple or efficiency specs with smaller or higher-ESR alternatives.
Does LM3671MFX-1.8/NOPB require an external feedback resistor network?
No. The LM3671MFX-1.8/NOPB integrates a precision resistor divider calibrated for 1.8-V output, connecting directly to its internal 0.5-V reference. The FB pin is internally terminated - no external resistors are needed, reducing BOM cost and eliminating resistor tolerance errors. This distinguishes it from the adjustable LM3671MF-ADJ variant, which requires external R1/R2. The LM3671MFX-1.8/NOPB's fixed architecture ensures ±4% output accuracy across temperature and line without user configuration.
How does LM3671MFX-1.8/NOPB handle thermal overload?
The LM3671MFX-1.8/NOPB incorporates a thermal shutdown circuit that disables switching when junction temperature reaches 150°C (typical) and re-enables operation once TJ drops to 130°C (typical). During sustained overload, this cycle prevents permanent damage while allowing safe recovery. The USON package's thermal metrics (RθJA = 174.7°C/W on 4-layer board) mean 600-mA operation at 5.5-V input requires ≥250 mm² copper pour under the exposed pad for reliable ambient operation up to 85°C. The LM3671MFX-1.8/NOPB also includes cycle-by-cycle current limiting at 1020 mA to prevent inductor saturation.
Can LM3671MFX-1.8/NOPB operate from a 2.5-V input?
No. The LM3671MFX-1.8/NOPB has a minimum recommended input voltage of 2.7 V per its Absolute Maximum Ratings and Recommended Operating Conditions. At 2.5 V, the internal PFET cannot fully enhance, causing excessive dropout, poor regulation, and potential thermal runaway. TI explicitly states "do not operate below 2.7 V" - even though the absolute max rating allows −0.2 V to GND, functional operation is invalid below 2.7 V. For sub-2.7-V inputs, consider the LM3674 series or discrete LDO alternatives. The LM3671MFX-1.8/NOPB's design assumes single Li-Ion battery operation starting at 2.7 V nominal discharge voltage.
What is the purpose of the SGND pin on LM3671MFX-1.8/NOPB?
The SGND (signal ground) pin on the LM3671MFX-1.8/NOPB provides a dedicated low-noise return path for the feedback amplifier and internal reference, isolated from high-current power ground paths. It must be connected to the main GND plane via a short, low-inductance trace near the FB pin - not daisy-chained through other grounds. This separation prevents switching noise from SW and inductor currents from modulating the 0.5-V reference, ensuring ±4% output accuracy. Omitting proper SGND routing degrades load regulation and increases output ripple. The LM3671MFX-1.8/NOPB relies on this pin for its specified performance; omitting it violates the validated layout.
LM3671MFX-1.8/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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.8V
- Voltage - Output (Max):
- -
- 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-1.8/NOPB FAQ
1.How can I place an order for LM3671MFX-1.8/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3671MFX-1.8/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-1.8/NOPB reliable?
The price and inventory of LM3671MFX-1.8/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-1.8/NOPB is usually 5 days.
3.What payment methods are accepted for LM3671MFX-1.8/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3671MFX-1.8/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3671MFX-1.8/NOPB?
LM3671MFX-1.8/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3671MFX-1.8/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-1.8/NOPB?
For technical support, including LM3671MFX-1.8/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3671MFX-1.8/NOPB requirements.
6.How does Aetrix verify that LM3671MFX-1.8/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3671MFX-1.8/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-1.8/NOPB meets industry standards.
7.What is the process for return or replacement of LM3671MFX-1.8/NOPB?
All LM3671MFX-1.8/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3671MFX-1.8/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-1.8/NOPB part is unused and in its original packaging.
Return procedure for LM3671MFX-1.8/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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