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Texas Instruments LM3674MFX-1.8
- Part No.:
- LM3674MFX-1.8
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MFX-1.8.pdf
- Description:
- IC REG BUCK 1.8V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,518
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Product details
Overview
LM3674MFX-1.8 from Texas Instruments is a fixed-output 1.8 V, 2-MHz synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered portable electronics. It delivers up to 600 mA load current from 2.7 V to 5.5 V input, features internal soft-start, 0.01 µA shutdown current, and operates in a 5-pin SOT-23 package with integrated PFET/NFET switches.
For engineers reviewing the LM3674MFX-1.8 datasheet, LM3674MFX-1.8 pinout, LM3674MFX-1.8 application, or LM3674MFX-1.8 equivalent, key selection criteria include its fixed 1.8 V output, 2 MHz switching frequency enabling ultra-compact 3-component designs (2.2 µH inductor + 4.7 µF CIN + 10 µF COUT), synchronous rectification efficiency, and thermal/current protection for mobile power rails.
Technical Context
The LM3674MFX-1.8 uses 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 feedback network eliminate external resistors, simplifying layout for stable 1.8 V output across temperature (−30°C to 125°C).
It integrates a 380 mΩ PFET switch and 250 mΩ NFET synchronous rectifier, enabling high efficiency at low output voltages. The device transitions seamlessly between PWM mode (2 MHz typical) and shutdown mode (0.01 µA IQ), with built-in current limit (1020 mA typ) and thermal shutdown for robust operation under transient overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.8 V ±4% - eliminates need for external feedback resistors and ensures stable core logic supply. |
| 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 USB 5 V rails. |
| Max Load Current | 600 mA - sufficient for powering ARM Cortex-M microcontrollers, RF transceivers, and display drivers. |
| Switching Frequency | 2 MHz (typical) - enables use of tiny 2.2 µH inductors and ceramic capacitors, reducing board area by >50% vs 500 kHz converters. |
| Shutdown Current | 0.01 µA (typical) - extends battery life during system sleep modes without external enable circuitry. |
| Internal Reference | 0.5 V - sets precise FB threshold; combined with fixed resistor divider, guarantees accurate 1.8 V output regardless of temperature drift. |
| Thermal Protection | Junction shutdown at 125°C - prevents damage during sustained overload or poor PCB thermal design. |
Pinout & Package
LM3674MFX-1.8 is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, optimized for space-constrained portable PCBs with exposed thermal pad (not electrically connected).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Accepts 2.7–5.5 V; requires local 4.7 µF ceramic capacitor to suppress high-frequency switching noise. |
| GND (Pin 2) | Ground reference | Common return path for input/output currents; must be connected to low-impedance ground plane. |
| EN (Pin 3) | Enable control | Logic-high (>1 V) enables regulation; <0.4 V forces shutdown; 0.01 µA leakage allows direct MCU GPIO control. |
| FB (Pin 4) | Feedback input | Internally tied to fixed resistor divider; monitors output voltage and adjusts duty cycle to maintain 1.8 V. |
| SW (Pin 5) | Switching node | Connects to inductor; carries high di/dt pulses; requires short, wide trace to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 380 mΩ PFET + 250 mΩ NFET reduces conduction loss, enabling >90% efficiency at 300 mA/1.8 V. |
| Internal soft-start | Gradual current limit ramp (70 → 140 → 280 → 1020 mA) limits inrush current, preventing input rail collapse during startup. |
| 2 MHz fixed-frequency PWM | Enables use of 2.2 µH shielded inductors and 0805-case ceramics, eliminating bulky ferrite beads and electrolytics. |
| Thermal & current protection | Auto-recovery thermal shutdown and cycle-by-cycle current limiting (1020 mA typ) protect IC and external components during fault conditions. |
| Low-noise operation | Voltage-mode control with feed-forward minimizes output ripple (<25 mV p-p at 300 mA) and improves transient response vs hysteretic regulators. |
Applications
| Mobile Phone Power Rail | WLAN Module Supply |
|---|---|
Use Scenario: Powers baseband processor core voltage in slim smartphone designs where board space and battery life are critical. IC Role / Device Role / Timing Role: Primary 1.8 V buck regulator delivering regulated power to ARM-based application processors. Use Value: 2 MHz switching allows compact 2.2 µH inductor + 10 µF ceramic output capacitor, reducing solution size by 40% vs legacy 500 kHz converters. | Use Scenario: Supplies clean 1.8 V to IEEE 802.11n WLAN transceivers requiring low-noise, fast-transient response power. IC Role / Device Role / Timing Role: Dedicated RF subsystem regulator with <25 mV output ripple and sub-10 µs load transient recovery. Use Value: Internal soft-start and synchronous rectification ensure stable startup and >88% efficiency at 400 mA, extending Wi-Fi session time. |
| Digital Camera Sensor Bias | Portable HDD Controller |
Use Scenario: Provides precision 1.8 V bias to CMOS image sensor analog front-end in compact digital still cameras. IC Role / Device Role / Timing Role: Low-noise, low-drift DC-DC source replacing LDOs to improve power efficiency without compromising SNR. Use Value: Fixed 1.8 V output with ±4% tolerance and 0.0010 %/mA load regulation maintains sensor ADC accuracy across varying current draw. | Use Scenario: Powers 1.8 V interface logic and buffer memory in 2.5-inch portable hard disk drives with thermal constraints. IC Role / Device Role / Timing Role: High-reliability buck converter with thermal shutdown protecting drive electronics during extended read/write bursts. Use Value: 125°C junction shutdown and 600 mA capability support continuous 500 mA operation in confined HDD enclosures. |
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; 0.6 V to 5.5 V adjustable output; 0.03 µA shutdown current. | Requires external feedback resistors; better suited for multi-rail systems needing programmable outputs. | Select when adjustable output or higher frequency (3 MHz) is required; not pin-compatible with LM3674MFX-1.8. |
| AP3012KTR-G1 | 1.5 MHz fixed frequency; 600 mA max; no internal soft-start; 1.5 µA shutdown current. | Lacks soft-start and thermal protection; lower integration increases external component count. | Choose for cost-sensitive designs where simplified protection and lower IQ are acceptable trade-offs. |
Compared with TPS62231DRVR and AP3012KTR-G1, the LM3674MFX-1.8 offers superior integration for fixed 1.8 V applications-its internal feedback, soft-start, and thermal shutdown reduce BOM count and improve reliability in space-constrained portable devices, while maintaining identical 5-pin SOT-23 footprint compatibility.
Availability
LM3674MFX-1.8 is available at Aetrix Electronics and suitable for mobile phones, WLAN modules, digital cameras, and portable HDD controllers requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3674MFX-1.8 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 over 50 years of innovation in power management ICs.
The LM3674 product line was designed specifically for ultra-compact, high-efficiency power conversion in battery-powered portable electronics, emphasizing minimal external components, low quiescent current, and robust protection features.
FAQ
What is the recommended input and output capacitor configuration for LM3674MFX-1.8?
The LM3674MFX-1.8 requires a 4.7 µF X5R/X7R ceramic capacitor (6.3 V rating) placed adjacent to the VIN pin and a 10 µF X5R/X7R ceramic capacitor (6.3 V rating) at the VOUT node. These values are validated for stable operation across −30°C to 85°C ambient and ensure <25 mV output ripple at 300 mA load. Larger capacitance improves transient response but is not required for basic functionality.
Does LM3674MFX-1.8 require external feedback resistors to set its output voltage?
No, the LM3674MFX-1.8 is a fixed-output variant with an internally trimmed resistor divider that sets the FB pin to regulate precisely at 1.8 V. Unlike the LM3674-ADJ version, it does not require external R1/R2 resistors-this simplifies layout, reduces component count, and eliminates resistor tolerance errors affecting output accuracy.
What is the maximum achievable efficiency of LM3674MFX-1.8 at 300 mA output current?
At 300 mA output current, 3.6 V input, and 25°C ambient, the LM3674MFX-1.8 achieves up to 92% efficiency, as confirmed by Figure 9 in the SNVS405G datasheet. This high efficiency results from synchronous rectification (380 mΩ PFET + 250 mΩ NFET) and 2 MHz operation minimizing inductor core losses and capacitor ESR heating.
Can LM3674MFX-1.8 operate with a 2.5 V input voltage?
No-LM3674MFX-1.8 has a minimum recommended input voltage of 2.7 V per Section 6.3 of the datasheet. At 2.5 V, the device may fail to start or drop out of regulation due to insufficient headroom for the internal PFET's RDSON and inductor DCR losses. For sub-2.7 V operation, consider an LDO or a different buck architecture.
How does the EN pin function on LM3674MFX-1.8, and what logic levels enable/disable it?
The EN pin on LM3674MFX-1.8 is a digital control input: applying >1 V (typical) enables regulation, while <0.4 V places the device in shutdown mode with 0.01 µA typical quiescent current. The pin draws only 0.01 µA, allowing direct connection to low-drive-strength MCU GPIOs without level-shifting or pull-up resistors.
LM3674MFX-1.8 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):
- 1.8V
- 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-1.8 FAQ
1.How can I place an order for LM3674MFX-1.8 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MFX-1.8 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-1.8 reliable?
The price and inventory of LM3674MFX-1.8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3674MFX-1.8 is usually 5 days.
3.What payment methods are accepted for LM3674MFX-1.8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MFX-1.8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MFX-1.8?
LM3674MFX-1.8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MFX-1.8 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-1.8?
For technical support, including LM3674MFX-1.8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MFX-1.8 requirements.
6.How does Aetrix verify that LM3674MFX-1.8 is sourced from the original manufacturer or authorized distributors?
All LM3674MFX-1.8 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-1.8 meets industry standards.
7.What is the process for return or replacement of LM3674MFX-1.8?
All LM3674MFX-1.8 units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MFX-1.8, 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-1.8 part is unused and in its original packaging.
Return procedure for LM3674MFX-1.8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3674MFX-1.8 Tags
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