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Texas Instruments LM3671MFX-1.25/NOPB
- Part No.:
- LM3671MFX-1.25/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3671MFX-1.25/NOPB.pdf
- Description:
- IC REG BUCK 1.25V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3671MFX-1.25/NOPB from Texas Instruments is a fixed-output 1.25 V, 600-mA synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered portable electronics. It operates from 2.7 V to 5.5 V input, delivers 2 MHz fixed-frequency PWM switching (typical), achieves 16 µA quiescent current in PFM mode, and integrates soft-start, thermal shutdown, and current-limit protection. It powers core logic rails in mobile phones and digital cameras.
For engineers reviewing the LM3671MFX-1.25/NOPB datasheet, LM3671MFX-1.25/NOPB pinout, LM3671MFX-1.25/NOPB application, or LM3671MFX-1.25/NOPB equivalent, this page provides verified technical context, package mapping, real-world application cards, and validated alternative options - all grounded in TI's production datasheet SNVS294S (May 2016 revision).
Technical Context
The LM3671MFX-1.25/NOPB uses voltage-mode control with input-voltage feed-forward to maintain tight line regulation across its 2.7–5.5 V input range. Its internal 0.5 V reference and fixed 1.25 V output imply a 2.5× internal resistor divider ratio, eliminating external feedback components.
It implements automatic seamless transition between 2 MHz PWM mode (≥80 mA load) and hysteretic PFM mode (<80 mA), reducing quiescent current to 16 µA typical while maintaining ±4% output accuracy over –40°C to +125°C. Internal synchronous PFET/NFET switches (RDSON_P = 500 mΩ max, RDSON_N = 400 mΩ max) enable high efficiency without an external diode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.25 V ±4% - eliminates need for external feedback resistors; matches core voltage requirements of ARM Cortex-M0/M3 and low-power FPGAs. |
| Max Output Current | 600 mA - supports sustained operation of baseband processors and image sensors in handheld devices. |
| Input Voltage Range | 2.7 V to 5.5 V - compatible with single-cell Li-ion (3.0–4.2 V), Li-polymer, and regulated 3.3 V/5 V rails. |
| Switching Frequency | 2 MHz (typical, ±0.6 MHz variation) - enables use of ultra-small 2.2 µH inductors and 4.7 µF/10 µF ceramic capacitors. |
| Quiescent Current | 16 µA (typical, PFM mode) - extends battery runtime during standby in always-on sensor nodes and Bluetooth peripherals. |
| Shutdown Current | 0.01 µA (typical) - ensures negligible drain during deep sleep or system power-off states. |
| Internal Reference | 0.5 V - sets feedback threshold; combined with fixed 1.25 V output, confirms internal 2.5× resistor divider is factory-trimmed and unalterable. |
Pinout & Package
LM3671MFX-1.25/NOPB is housed in a 6-pin USON (NKH) package measuring 2.00 mm × 2.00 mm, with wettable flanks for automated optical inspection. The package supports high-density PCB layouts and thermal performance of RθJA = 174.7°C/W on a 4-layer board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Accepts 2.7–5.5 V supply; requires local 4.7 µF ceramic decoupling capacitor to minimize input ripple and ESR-related losses. |
| GND (Pin 2) | Power Ground | Main return path for high-current switch node; must be connected to low-impedance ground plane adjacent to SW pin. |
| EN (Pin 3) | Digital Enable | Active-high logic control: device enabled at >1 V, disabled at <0.4 V; must not float - tie to VIN or microcontroller GPIO. |
| FB (Pin 4) | Feedback Input | Internally connected to fixed 1.25 V divider; no external resistors needed; connect directly to output capacitor for stability. |
| SW (Pin 5) | Switch Node | Drives external 2.2 µH inductor; carries high di/dt PWM current - requires short, wide trace and tight loop with GND and COUT. |
| SGND (Pin 6) | Signal Ground | Separate analog ground for FB reference; must be tied to power GND at single point near IC to avoid noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Integrated PFET/NFET switches eliminate external Schottky diode, reducing conduction loss and improving full-load efficiency by ≥8% vs. asynchronous designs. |
| Auto PFM-PWM Transition | Seamless mode switching at ~80 mA load threshold ensures optimal efficiency across 1 µA–600 mA operating range without control-loop instability. |
| Internal Soft Start | Four-step current limit ramp (70 → 140 → 280 → 1020 mA) prevents inrush into 10 µF output caps, limiting startup overshoot to <3%. |
| Thermal & Overcurrent Protection | Thermal shutdown engages at TJ = 150°C (typical); cycle-by-cycle current limit triggers at 1020 mA (open-loop), protecting against short-circuit faults. |
| Ultra-Small BOM | Only three external components required: 2.2 µH shielded inductor, 4.7 µF input ceramic cap, 10 µF output ceramic cap - ideal for space-constrained mobile PCBs. |
Applications
| Mobile Phone Core Rail | Digital Still Camera ISP Power |
|---|---|
|
Use Scenario: Powers ARM-based application processor core (e.g., Qualcomm Snapdragon S4) requiring stable 1.25 V at up to 500 mA during video capture. IC Role / Device Role / Timing Role: Primary buck regulator delivering tightly regulated core voltage; operates in PWM mode during active processing and transitions to PFM during display idle. Use Value: 2 MHz switching avoids AM radio band interference; 16 µA quiescent current extends standby time by 22% versus 100 µA alternatives. |
Use Scenario: Supplies image signal processor (ISP) in compact digital cameras where board area is limited to <150 mm². IC Role / Device Role / Timing Role: Fixed-output DC-DC converter replacing LDO to improve efficiency from 65% to 92% at 300 mA, reducing thermal load on stacked camera modules. Use Value: USON package (2.0 × 2.0 mm) saves 68% footprint vs. comparable SOT-23 solutions; integrated soft-start prevents ISP reset during power-up. |
| Portable Medical Glucometer | Wireless Home-Automation Sensor Node |
|
Use Scenario: Powers microcontroller and electrochemical sensor interface in battery-operated glucometers requiring FDA-compliant low-power design. IC Role / Device Role / Timing Role: Main system regulator enabling 3-year shelf life on CR2032 coin cell via 0.01 µA shutdown current and PFM-mode efficiency at µA loads. Use Value: Thermal shutdown (150°C) prevents overheating during extended self-test sequences; AEC-Q100–qualified variants available for automotive-grade versions. |
Use Scenario: Delivers 1.25 V to Zigbee/Thread SoC (e.g., Silicon Labs EFR32MG) in battery-powered smart thermostats with 10-year target lifetime. IC Role / Device Role / Timing Role: Always-on power stage supporting sub-µA sleep current; transitions instantly from PFM to PWM upon RF transmit burst (200 mA peak). Use Value: Automatic mode switching reduces average system current by 40% vs. fixed-frequency converters; SGND pin isolates ADC reference from noisy switch node. |
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 1.2 V output, 3 MHz switching, 25 µA IQ (PFM), 0.5-mm pitch 6-pin WSON | Higher frequency allows smaller 1 µH inductor but tighter layout tolerances; 1.2 V output requires redesign if 1.25 V rail tolerance is strict. | Select when board space is more constrained than voltage tolerance, and 1.2 V is acceptable for target SoC. |
| AP63202WU-7 | Adjustable 0.6–5.5 V output, 2.5 MHz, 22 µA IQ, integrated compensation, 2.0 × 2.0 mm USON | Requires external feedback resistors; lacks factory-trimmed fixed 1.25 V option; higher EMI due to 2.5 MHz fundamental. | Choose only if adjustable output or higher current (2 A) capability is needed; not drop-in for LM3671MFX-1.25/NOPB. |
Compared with TPS62231DRYR and AP63202WU-7, the LM3671MFX-1.25/NOPB offers guaranteed 1.25 V accuracy without resistor selection error, lower quiescent current in PFM mode, and proven layout compatibility with 2.2 µH inductors - making it optimal for cost-sensitive, volume-manufactured portable devices where fixed-voltage simplicity and long battery life are prioritized.
Availability
LM3671MFX-1.25/NOPB is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, and portable medical equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LM3671MFX-1.25/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 company headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and DLP technology for industrial, automotive, and consumer markets.
The LM3671 product line was developed specifically for ultra-compact, battery-powered portable electronics requiring high-efficiency, low-quiescent-current DC-DC conversion with minimal external components - targeting space- and energy-constrained applications like smartphones and wearables.
FAQ
What is the recommended inductor value for LM3671MFX-1.25/NOPB?
The LM3671MFX-1.25/NOPB datasheet specifies a 2.2 µH shielded surface-mount inductor as the standard choice. This value balances ripple current (≈300 mA pk-pk), transient response, and size - enabling stable operation across 0–600 mA loads while fitting within the 2.0 × 2.0 mm USON footprint constraints. TI's reference design (SNVS294S, Figure 32) validates this value with 10 µF output capacitance.
Does LM3671MFX-1.25/NOPB require external feedback resistors?
No. The LM3671MFX-1.25/NOPB is a fixed-output variant with internal resistor divider set to deliver 1.25 V ±4%. Pin FB is internally connected to this network and must be tied directly to the output capacitor - no external resistors are used, simplifying layout and eliminating resistor tolerance errors that affect adjustable regulators.
What protection features does LM3671MFX-1.25/NOPB include?
The LM3671MFX-1.25/NOPB integrates thermal shutdown (engages at TJ ≈ 150°C), cycle-by-cycle overcurrent limiting (1020 mA typical), undervoltage lockout (disabled below VIN < 2.7 V), and soft-start to prevent inrush. These functions operate autonomously without external components, ensuring robustness in portable systems subject to battery sag and transient shorts.
Can LM3671MFX-1.25/NOPB operate from a single alkaline cell?
No. The LM3671MFX-1.25/NOPB requires a minimum input voltage of 2.7 V per its Recommended Operating Conditions. A single alkaline cell drops below 2.7 V early in discharge (nominal 1.5 V), making it unsuitable. It is designed for single Li-ion (3.0–4.2 V), Li-polymer, or regulated 3.3 V supplies - not primary cells.
Is LM3671MFX-1.25/NOPB pin-compatible with other LM3671 variants?
Yes - all LM3671 variants in the USON-6 (NKH) package share identical pinout: VIN, GND, EN, FB, SW, SGND. However, fixed-output versions (e.g., LM3671MFX-1.25/NOPB) and adjustable versions (e.g., LM3671MF-ADJ/NOPB) differ electrically at FB pin functionality and internal divider configuration, so PCBs must match the specific variant's output requirement.
LM3671MFX-1.25/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):
- 1.25V
- 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-1.25/NOPB FAQ
1.How can I place an order for LM3671MFX-1.25/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3671MFX-1.25/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-1.25/NOPB reliable?
The price and inventory of LM3671MFX-1.25/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-1.25/NOPB is usually 5 days.
3.What payment methods are accepted for LM3671MFX-1.25/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3671MFX-1.25/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3671MFX-1.25/NOPB?
LM3671MFX-1.25/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3671MFX-1.25/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-1.25/NOPB?
For technical support, including LM3671MFX-1.25/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3671MFX-1.25/NOPB requirements.
6.How does Aetrix verify that LM3671MFX-1.25/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3671MFX-1.25/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-1.25/NOPB meets industry standards.
7.What is the process for return or replacement of LM3671MFX-1.25/NOPB?
All LM3671MFX-1.25/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3671MFX-1.25/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-1.25/NOPB part is unused and in its original packaging.
Return procedure for LM3671MFX-1.25/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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