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Texas Instruments LM3674MFX-1.2
- Part No.:
- LM3674MFX-1.2
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MFX-1.2.pdf
- Description:
- IC REG BUCK 1.2V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,277
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Product details
Overview
LM3674MFX-1.2 from Texas Instruments is a fixed-output 1.2 V, 2-MHz synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered portable systems. It delivers up to 600 mA load current across 2.7–5.5 V input range, features internal soft-start, 0.01 µA shutdown current, and operates in PWM mode with voltage-mode control and input feed-forward for high line/load regulation.
For engineers reviewing the LM3674MFX-1.2 datasheet, LM3674MFX-1.2 pinout, LM3674MFX-1.2 application, or LM3674MFX-1.2 equivalent, this page provides verified functional identity, confirmed SOT-23-5 package mapping, validated pin functions, real-world efficiency curves at 1.2 V output, and two technically documented alternative parts with explicit parameter-level differences.
Technical Context
The LM3674MFX-1.2 uses voltage-mode PWM control with input voltage feed-forward to maintain stable regulation under dynamic line and load conditions. Its internal 0.5 V reference feeds an error amplifier that compares FB voltage against VREF to modulate PFET on-time at a fixed 2 MHz switching frequency.
Synchronous rectification employs an integrated NFET (RDSON(N) = 250–400 mΩ) alongside the PFET (RDSON(P) = 380–500 mΩ) to eliminate external diode losses. Current limiting triggers at 1020 mA (typical), and thermal shutdown activates at TJ ≥ 125°C - both implemented in hardware without software dependency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V ±4% - internally trimmed; no external resistors required for regulation. |
| 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). |
| Max Load Current | 600 mA continuous - sustained across full input range and −30°C to +125°C junction temperature. |
| Switching Frequency | 2 MHz typical (1.6–2.6 MHz over temp) - enables use of small 2.2 µH inductor and 10 µF ceramic output capacitor. |
| Shutdown Current | 0.01 µA typical - reduces battery drain during system sleep; EN pin < 0.4 V disables all circuitry. |
| Feedback Reference | 0.5 V internal - sets output via internal resistor divider; FB pin monitors regulated output directly. |
| Thermal Protection | Junction shutdown at 125°C - automatically recovers after cooldown; no latch-up or manual reset required. |
Pinout & Package
LM3674MFX-1.2 is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm with standard lead pitch and thermal pad omitted.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Accepts 2.7–5.5 V; requires 4.7 µF ceramic input capacitor placed adjacent to minimize high-frequency ripple. |
| GND (Pin 2) | Ground reference | Primary return path for input, output, and internal switch currents; must be low-impedance PCB plane. |
| EN (Pin 3) | Digital enable | Active-high logic input; device enabled when >1 V, disabled when <0.4 V; 0.01 µA leakage ensures minimal standby loss. |
| FB (Pin 4) | Analog feedback | Monitors regulated 1.2 V output directly; internal divider sets VOUT = 1.2 V; no external resistors needed. |
| SW (Pin 5) | Switching node | Connects to PFET drain and NFET source; drives external 2.2 µH inductor; carries high di/dt square wave. |
Key Features
| Feature | Design Value |
|---|---|
| Internal synchronous rectification | Eliminates external Schottky diode; achieves >90% peak efficiency at 300 mA/1.2 V with 2.2 µH inductor. |
| 2-MHz fixed-frequency PWM | Enables compact BOM: only three external components (CIN, COUT, L1) required for full operation. |
| 0.5 V internal reference | Provides precise 1.2 V output without trimming or external feedback network; reduces layout sensitivity. |
| Integrated soft-start | Prevents inrush current at startup by stepping current limit (70 → 140 → 280 → 1020 mA); start-up time ~240–350 µs. |
| Thermal + current protection | Hardware-based safeguards prevent damage during overload or ambient overheating; no firmware or configuration needed. |
Applications
| Mobile Phone Power Rail | MP3 Player Core Logic Supply |
|---|---|
Use Scenario: Powers baseband processor core voltage in slim-profile GSM/3G handsets using single-cell Li-Ion battery. IC Role / Device Role / Timing Role: Primary buck regulator delivering stable 1.2 V to CPU core; operates continuously during active mode and enters ultra-low-IQ shutdown during idle. Use Value: Enables >90% conversion efficiency at 300 mA load, minimizing heat buildup in sealed enclosure and extending talk time by reducing quiescent loss. |
Use Scenario: Supplies 1.2 V to DSP and audio codec in portable MP3 players with tight board space constraints. IC Role / Device Role / Timing Role: Fixed-output DC-DC converter replacing linear regulator; switches at 2 MHz to avoid audible noise in audio band. Use Value: Reduces power dissipation by 65% vs LDO solution at 400 mA, allowing use of smaller battery and eliminating need for heatsinking. |
| Digital Still Camera Sensor Bias | Portable Instrument Low-Noise MCU Supply |
Use Scenario: Generates clean 1.2 V supply for CMOS image sensor analog front-end in compact digital cameras. IC Role / Device Role / Timing Role: High-efficiency buck converter with low output ripple; SW node routed away from analog traces per layout guidelines. Use Value: Achieves <25 mVpp output ripple with 10 µF X5R ceramic capacitor, meeting sensor PSRR requirements without additional LC filtering. |
Use Scenario: Powers ARM Cortex-M0+ microcontroller in handheld test equipment requiring long battery life and stable brownout behavior. IC Role / Device Role / Timing Role: Main system regulator with undervoltage lockout (UVLO) and thermal shutdown; EN pin controlled by MCU for sequenced power-up. Use Value: Maintains regulation down to VIN = 2.7 V while delivering 600 mA, ensuring reliable operation across full battery discharge cycle. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | 1.2 V fixed, 3-MHz switching, 400-mA max load, 3.5-µA quiescent current in PWM mode | Higher frequency allows smaller inductor but lower max current; less suitable for 600-mA camera sensor rails | Select when board space is critical and load ≤400 mA; verify thermal performance with 3-MHz switching losses. |
| AP3012KTR-G1 | 1.2 V fixed, 1.5-MHz switching, 500-mA max load, no internal synchronous rectifier (requires external diode) | Lower efficiency (~82% at 300 mA) due to diode conduction loss; higher thermal footprint | Choose only if cost is primary constraint and efficiency >85% is not required; add Schottky diode and re-evaluate layout area. |
Compared with LM3674MFX-1.2, TPS62231DRYR trades 200 mA load capacity for higher switching frequency and smaller passive size, while AP3012KTR-G1 sacrifices efficiency and integration to reduce unit cost - neither matches the 600-mA capability, 2-MHz optimization, and fully integrated synchronous design of LM3674MFX-1.2.
Availability
LM3674MFX-1.2 is available at Aetrix Electronics and suitable for mobile phones, portable instruments, digital still cameras, and MP3 players requiring stable component supply with guaranteed long-term manufacturability and consistent electrical specifications.
Supply support for LM3674MFX-1.2 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 power management solutions for industrial, automotive, and consumer markets.
The LM3674 product line was developed specifically for space-constrained portable electronics requiring high-efficiency, low-noise, single-cell Li-Ion compatible DC-DC conversion with minimal external components.
FAQ
What is the maximum output current supported by the LM3674MFX-1.2?
The LM3674MFX-1.2 supports up to 600 mA of continuous output current across its full operating temperature range (−30°C to +125°C) and input voltage range (2.7 V to 5.5 V), as specified in the Electrical Characteristics table of the SNVS405G datasheet. This rating assumes proper PCB thermal design using a 2-layer or 4-layer board per the RθJA values provided.
Does the LM3674MFX-1.2 require external feedback resistors to set the 1.2 V output?
No, the LM3674MFX-1.2 does not require external feedback resistors. It is a fixed-output variant with an internal resistor divider configured to deliver 1.2 V; the FB pin connects directly to the output capacitor. External resistors are only required for the adjustable LM3674-ADJ version, which uses a 0.5 V internal reference.
What package type and dimensions does the LM3674MFX-1.2 use?
The LM3674MFX-1.2 is packaged in a 5-pin SOT-23 (DBV) case with nominal body dimensions of 2.90 mm × 1.60 mm. Pin assignment follows TI's standard DBV top-view layout: VIN (1), GND (2), EN (3), FB (4), SW (5). No thermal pad is included in this variant.
How does the LM3674MFX-1.2 achieve high efficiency at light loads?
The LM3674MFX-1.2 maintains high efficiency at light loads through internal synchronous rectification - using an integrated NFET instead of a lossy external diode - and a low 300 µA typical quiescent current (IQ) in active PWM mode. Its 2-MHz fixed-frequency operation avoids frequency scaling artifacts, preserving regulation accuracy even below 10 mA output.
Can the LM3674MFX-1.2 operate with an input voltage below 2.7 V?
No, the LM3674MFX-1.2 is not specified to operate reliably below 2.7 V input. The Recommended Operating Conditions table explicitly defines 2.7 V as the minimum input voltage. Operation below this threshold may result in undervoltage lockout activation, unregulated output, or failure to start - particularly critical during Li-Ion battery end-of-discharge.
LM3674MFX-1.2 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):
- 1.2V
- 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-1.2 FAQ
1.How can I place an order for LM3674MFX-1.2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MFX-1.2 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-1.2 reliable?
The price and inventory of LM3674MFX-1.2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3674MFX-1.2 is usually 5 days.
3.What payment methods are accepted for LM3674MFX-1.2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MFX-1.2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MFX-1.2?
LM3674MFX-1.2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MFX-1.2 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-1.2?
For technical support, including LM3674MFX-1.2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MFX-1.2 requirements.
6.How does Aetrix verify that LM3674MFX-1.2 is sourced from the original manufacturer or authorized distributors?
All LM3674MFX-1.2 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-1.2 meets industry standards.
7.What is the process for return or replacement of LM3674MFX-1.2?
All LM3674MFX-1.2 units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MFX-1.2, 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-1.2 part is unused and in its original packaging.
Return procedure for LM3674MFX-1.2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3674MFX-1.2 Tags
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