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Texas Instruments LM3674MFX-1.875
- Part No.:
- LM3674MFX-1.875
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MFX-1.875.pdf
- Description:
- IC REG BUCK 1.875V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,140
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Product details
Overview
LM3674MFX-1.875 from Texas Instruments is a fixed-output, 2-MHz synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered systems. It delivers up to 600 mA load current with 1.875 V output, operates from 2.7 V to 5.5 V input, features internal soft-start and 0.01 µA shutdown current, and targets power rails in mobile phones and portable instrumentation.
For engineers reviewing the LM3674MFX-1.875 datasheet, LM3674MFX-1.875 pinout, LM3674MFX-1.875 application, or LM3674MFX-1.875 equivalent, key selection criteria include its fixed 1.875 V output, SOT-23-5 package footprint, 2 MHz switching frequency enabling compact 2.2 µH inductor + 10 µF/4.7 µF ceramic capacitor design, and integrated PFET/NFET synchronous rectification for high efficiency at low output voltages.
Technical Context
The LM3674MFX-1.875 employs voltage-mode PWM control with input voltage feed-forward to achieve tight line regulation (0.083 %/V) and load regulation (0.0010 %/mA). Its internal 0.5 V reference and fixed resistor divider set the regulated output precisely to 1.875 V without external feedback components.
It integrates a 380 mΩ PFET switch and 250 mΩ NFET synchronous rectifier, enabling high-efficiency operation across 2.7–5.5 V input while delivering 600 mA. Thermal shutdown, current overload protection, and undervoltage lockout ensure robust operation in portable environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.875 V - eliminates need for external feedback resistors and simplifies layout for stable low-noise rail generation. |
| 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) plus margin for transient spikes. |
| Max Load Current | 600 mA - sufficient for powering core logic, RF transceivers, or sensor subsystems in handheld devices. |
| Switching Frequency | 2 MHz (typical) - enables use of small 2.2 µH shielded inductor and 10 µF/4.7 µF X5R/X7R ceramic capacitors, minimizing board area. |
| Shutdown Current | 0.01 µA (typical) - extends battery life during system sleep modes without requiring external load switches. |
| Feedback Reference | 0.5 V internal - sets precise output via internal resistor divider; no external FB network required for fixed versions. |
| Thermal Protection | 125 °C junction limit - automatically disables switching to prevent damage during sustained overload or poor thermal dissipation. |
Pinout & Package
SOT-23-5 package (2.90 mm × 1.60 mm body size) with exposed pad not electrically connected; rated for 130 °C/W junction-to-ambient thermal resistance on 4-layer PCB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Connects to input filter capacitor (4.7 µF); must be ≥2.7 V for startup; supplies internal bias and PFET switch. |
| GND (Pin 2) | Ground reference | Primary return path for input/output currents and internal circuitry; requires low-impedance connection to PCB ground plane. |
| EN (Pin 3) | Enable control | Logic-high (>1 V) enables regulation; <0.4 V forces shutdown mode with 0.01 µA quiescent draw; must not float. |
| FB (Pin 4) | Feedback node | Internally connected to fixed resistor divider; unused externally for LM3674MFX-1.875 - leave unconnected per datasheet. |
| SW (Pin 5) | Switching node | Drives external inductor; carries high di/dt square wave; requires short, low-inductance trace to minimize EMI and voltage overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Internal synchronous rectification | Integrated 250 mΩ NFET replaces external Schottky diode, reducing conduction loss and improving efficiency by ~8–12% at 300 mA load. |
| 2-MHz fixed-frequency PWM | Enables consistent EMI profile and eliminates need for external frequency programming; supports ultra-compact passive component selection. |
| Internal soft-start | Ramps output voltage over ~240–350 µs (depending on COUT and load), limiting inrush current to protect input source and downstream circuitry. |
| Current limit protection | 1020 mA typical peak switch current limit prevents destructive overcurrent during short-circuit or heavy transient events. |
| Thermal shutdown | Activates at 125 °C junction temperature and holds device off until temperature falls below hysteresis threshold (~15 °C). |
Applications
| Mobile Phone Core Rail | Portable Instrument ADC Supply |
|---|---|
Use Scenario: Powers baseband processor core voltage in GSM/UMTS smartphones operating from single-cell Li-Ion battery. IC Role / Device Role / Timing Role: Primary buck regulator generating stable 1.875 V supply for digital logic and memory interfaces. Use Value: Delivers 600 mA at >88% efficiency across 3.0–4.2 V input range, with 2 MHz switching enabling minimal BOM count (3 passives) and fast transient response to CPU burst loads. | Use Scenario: Supplies precision analog-to-digital converter (ADC) reference and analog front-end in handheld multimeters or data loggers. IC Role / Device Role / Timing Role: Low-noise, tightly regulated DC-DC source replacing LDO to improve power efficiency without sacrificing voltage accuracy. Use Value: 0.083 %/V line regulation and 0.0010 %/mA load regulation maintain ±1.5 mV output stability over battery discharge and varying sensor load conditions. |
| W-LAN Baseband Power | Digital Still Camera Image Sensor Bias |
Use Scenario: Provides clean 1.875 V rail for Wi-Fi baseband ICs in portable hotspot devices or tablets. IC Role / Device Role / Timing Role: High-frequency buck converter decoupled from noisy RF sections via LC filtering; SW node isolated from sensitive analog traces. Use Value: 2 MHz operation shifts switching noise above critical 2.4 GHz ISM band harmonics, easing EMI filtering and improving RF coexistence. | Use Scenario: Generates bias voltage for CMOS image sensor digital core in compact digital cameras. IC Role / Device Role / Timing Role: Efficient point-of-load regulator placed near sensor module to minimize IR drop and noise coupling. Use Value: 0.01 µA shutdown current preserves battery charge during camera standby; internal soft-start prevents sensor initialization faults caused by output voltage slew rate. |
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 output; 3 MHz switching; 0.02 µA shutdown; 400 mA max load. | Lower output voltage and reduced current capability; better suited for ultra-low-power microcontrollers than 600 mA loads. | Select when 1.8 V matches system requirement and higher frequency allows smaller inductors, but verify load headroom. |
| AP3012KTR-G1 | Fixed 1.8 V output; 1.5 MHz switching; 0.1 µA shutdown; 300 mA max load; no internal synchronous rectifier. | Lower efficiency due to external diode; insufficient current for 600 mA applications; requires additional diode and larger output capacitor. | Consider only for cost-sensitive, lower-current designs where efficiency and board space are secondary concerns. |
Compared with TPS62231DRYR and AP3012KTR-G1, the LM3674MFX-1.875 provides 75 mV higher output voltage, 200 mA greater load capacity, and integrated synchronous rectification-making it uniquely suitable for 1.875 V rails demanding full 600 mA at high efficiency in space-constrained Li-Ion systems.
Availability
LM3674MFX-1.875 is available at Aetrix Electronics and suitable for mobile phone power management, portable instrument DC-DC conversion, and W-LAN baseband supply applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LM3674MFX-1.875 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 specializing in analog and embedded processing technologies, with leadership in power management ICs for portable and industrial applications.
The LM3674 product line delivers compact, high-frequency synchronous buck converters for battery-powered devices, designed specifically to replace inefficient linear regulators while minimizing external component count and PCB area.
FAQ
What is the output voltage tolerance of the LM3674MFX-1.875 under full operating conditions?
The LM3674MFX-1.875 has a guaranteed output voltage tolerance of ±4% over –30°C to 125°C junction temperature, 2.7 V to 5.5 V input, and 0–600 mA load. This is derived from the ±4% feedback voltage (VFB) specification referenced to the internal 0.5 V bandgap, which directly determines the 1.875 V output via fixed resistor ratio. No external calibration or trimming is required.
Can the LM3674MFX-1.875 operate with an input voltage below 2.7 V?
No - the LM3674MFX-1.875 incorporates undervoltage lockout (UVLO) that prevents startup until VIN reaches ≥2.7 V. Below this threshold, the device remains in shutdown state regardless of EN pin status. Attempting to operate below 2.7 V risks unstable regulation or failure to initiate soft-start; TI specifies 2.7 V as the absolute minimum recommended input for reliable operation.
Is an external feedback resistor network required for the LM3674MFX-1.875?
No - the LM3674MFX-1.875 is a fixed-output variant with internal resistor divider configured for 1.875 V. Pin 4 (FB) is internally connected and must remain unconnected on the PCB. Adding external resistors would disrupt regulation and is explicitly prohibited in the datasheet. Only adjustable versions (e.g., LM3674-ADJ) require external R1/R2.
What is the maximum achievable efficiency of the LM3674MFX-1.875 at 300 mA load?
At 300 mA load, 3.6 V input, and 25°C ambient, the LM3674MFX-1.875 achieves up to 92% peak efficiency - as shown in Figure 10 of the SNVS405G datasheet. This value assumes optimal layout, 2.2 µH inductor with ≤200 mΩ DCR, and 10 µF/4.7 µF X5R ceramic capacitors. Efficiency drops to ~85% at 600 mA due to increased conduction losses in the internal PFET/NFET switches.
Does the LM3674MFX-1.875 support 100% duty-cycle operation for dropout scenarios?
No - the LM3674MFX-1.875 does not support 100% duty-cycle operation. That feature is exclusive to the adjustable LM3674-ADJ version, which can enter LDO-like mode when VIN approaches VOUT. The fixed-output LM3674MFX-1.875 requires minimum headroom (VIN ≥ VOUT + ILOAD × [RDSON(P) + RINDUCTOR]) to maintain regulation; below this, output collapses.
LM3674MFX-1.875 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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):
- 1.875V
- Voltage - Output (Max):
- -
- Current - Output:
- 600mA
- Frequency - Switching:
- 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM3674MFX-1.875 FAQ
1.How can I place an order for LM3674MFX-1.875 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MFX-1.875 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 LM3674MFX-1.875 reliable?
The price and inventory of LM3674MFX-1.875 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3674MFX-1.875 is usually 5 days.
3.What payment methods are accepted for LM3674MFX-1.875?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MFX-1.875 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MFX-1.875?
LM3674MFX-1.875 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MFX-1.875 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 LM3674MFX-1.875?
For technical support, including LM3674MFX-1.875 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MFX-1.875 requirements.
6.How does Aetrix verify that LM3674MFX-1.875 is sourced from the original manufacturer or authorized distributors?
All LM3674MFX-1.875 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 LM3674MFX-1.875 meets industry standards.
7.What is the process for return or replacement of LM3674MFX-1.875?
All LM3674MFX-1.875 units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MFX-1.875, 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 LM3674MFX-1.875 part is unused and in its original packaging.
Return procedure for LM3674MFX-1.875:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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