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Texas Instruments LM3674MF-1.2
- Part No.:
- LM3674MF-1.2
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MF-1.2.pdf
- Description:
- IC REG BUCK 1.2V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,858
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Product details
Overview
LM3674MF-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 LM3674MF-1.2 datasheet, LM3674MF-1.2 pinout, LM3674MF-1.2 application, or LM3674MF-1.2 equivalent, key selection considerations include its SOT-23-5 package footprint, 1.2 V fixed output with ±4% feedback tolerance, 2.2 µH inductor + dual ceramic capacitor (4.7 µF/10 µF) minimal external component count, and thermal/current protection for mobile power rail design.
Technical Context
The LM3674MF-1.2 implements a voltage-mode PWM controller with internal 0.5 V reference and input voltage feed-forward to maintain stable regulation under varying line conditions. Its functional block includes integrated PFET/NFET synchronous rectifier switches, current-limit comparator (1020 mA typical), thermal shutdown, undervoltage lockout, and soft-start circuitry that ramps switch current limit in discrete steps (70/140/280/1020 mA).
It operates exclusively in PWM mode across full 0–600 mA load range-no PFM or burst mode-and relies on external 2.2 µH shielded inductor and low-ESR ceramic capacitors to achieve >90% peak efficiency at 300 mA (VIN = 3.6 V, VOUT = 1.2 V). The fixed 1.2 V output is internally trimmed; no external feedback resistors are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V ±4% over −30°C to 125°C junction temperature |
| 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 at 1.2 V output without thermal derating on 4-layer PCB |
| Switching Frequency | 2 MHz typical (1.6–2.6 MHz over temp) - enables use of tiny 2.2 µH inductor and 0805-size ceramics |
| Shutdown Current | 0.01 µA typical - preserves battery life during system sleep modes |
| Feedback Reference | 0.5 V internal - sets output via internal resistor divider; no external R1/R2 needed for fixed versions |
| Thermal Protection | 125°C junction shutdown - automatically recovers after cooldown; prevents permanent damage in overload |
Pinout & Package
SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm height, gull-wing leads, RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Connects to input filter capacitor (4.7 µF ceramic); must be ≥2.7 V for enable; max 6 V absolute rating |
| GND (Pin 2) | Ground reference | Primary return path for input/output currents and IC bias; requires low-impedance PCB plane connection |
| EN (Pin 3) | Digital enable | Logic-high (>1 V) enables operation; <0.4 V forces shutdown; 0.01 µA input current minimizes leakage impact |
| FB (Pin 4) | Feedback node | Internally connected to 1.2 V output divider; not accessible externally on fixed-voltage variants |
| SW (Pin 5) | Switching node | Drives external inductor; carries high di/dt square wave (2 MHz); requires tight layout to minimize EMI |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated NFET replaces Schottky diode - eliminates 0.3–0.4 V forward drop, enabling >92% efficiency at 1.2 V/300 mA |
| Internal soft-start | Gradual current limit ramp (70→140→280→1020 mA) - limits inrush into 10 µF output cap, preventing VIN sag during startup |
| Thermal & current protection | Auto-shutdown at 125°C junction temp and >1020 mA peak switch current - protects IC and inductor under fault conditions |
| Minimal BOM requirement | Only three external components needed: 2.2 µH inductor, 4.7 µF input cap, 10 µF output cap - reduces board area and cost vs. non-synchronous alternatives |
| Low-noise PWM operation | Fixed 2 MHz frequency avoids AM/FM radio bands; combined with shielded inductor, meets Class B EMI limits in handheld layouts |
Applications
| Mobile Phone Core Logic | Wireless LAN (WLAN) Baseband |
|---|---|
Use Scenario: Powers ARM Cortex-A series application processor core rail requiring stable 1.2 V at up to 600 mA during burst-mode video decode. IC Role / Device Role / Timing Role: Primary buck regulator delivering clean, low-noise 1.2 V supply directly to SoC VDD_CORE pins. Use Value: 2 MHz switching allows compact 2.2 µH inductor placement near processor, minimizing trace inductance and improving transient response to 200 mA/µs load steps. | Use Scenario: Supplies 1.2 V to IEEE 802.11a/b/g/n WLAN transceiver baseband IC during active packet transmission. IC Role / Device Role / Timing Role: Dedicated point-of-load converter isolating RF-sensitive analog sections from digital switching noise. Use Value: Synchronous architecture achieves >90% efficiency at light loads (10 mA), extending battery runtime in standby while maintaining <15 mVpp ripple. |
| Portable Digital Camera Sensor | MP3 Player DSP Core |
Use Scenario: Provides regulated 1.2 V to CMOS image sensor logic and ADC interface during high-speed capture sequences. IC Role / Device Role / Timing Role: Low-noise power source synchronized to sensor frame timing to prevent rolling shutter artifacts. Use Value: Fixed-frequency PWM ensures predictable EMI spectrum; 0.01 µA shutdown current enables instant-on wake from deep sleep without capacitor recharge delay. | Use Scenario: Powers 1.2 V DSP core in flash-based audio player during MP3 decoding and DAC interface operation. IC Role / Device Role / Timing Role: Main system regulator supporting dynamic voltage scaling based on audio workload. Use Value: Input range (2.7–5.5 V) accommodates full Li-Ion discharge; internal soft-start prevents brownout during cold boot from depleted battery. |
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 | 1.2 V fixed, 3 MHz switching, 600 mA, 0.02 µA shutdown, same SOT-23-5 package | Higher frequency enables smaller 1.0 µH inductor but increases switching losses above 400 mA | Preferred when board space is constrained and efficiency above 400 mA is secondary to size |
| AP3012KTR-G1 | 1.2 V fixed, 1.5 MHz switching, 600 mA, 1 µA shutdown, SOT-23-5, no internal soft-start | Lacks soft-start - requires external RC network to limit inrush; higher shutdown current impacts ultra-low-power sleep | Acceptable where cost is primary driver and startup sequencing is managed externally |
Compared with TPS62231DRYR and AP3012KTR-G1, the LM3674MF-1.2 offers superior light-load efficiency due to lower quiescent current and integrated soft-start, making it optimal for battery-critical portable devices where rapid, reliable startup and multi-day standby are required.
Availability
LM3674MF-1.2 is available at Aetrix Electronics and suitable for mobile phones, WLAN modules, digital cameras, and MP3 players requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for LM3674MF-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 leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-efficiency DC-DC conversion for portable electronics.
The LM3674 product line was designed specifically for space-constrained, battery-powered applications demanding high efficiency at low output voltages (1.0–3.3 V), minimal external components, and robust protection in harsh thermal environments.
FAQ
What is the recommended inductor value for LM3674MF-1.2?
The LM3674MF-1.2 is optimized for a 2.2 µH shielded inductor with ≥1200 mA saturation current rating and ≤200 mΩ DCR. TI recommends Coilcraft DO3314-222MX or Panasonic ELL5GM2R2N. Using this value ensures stable 2 MHz operation, <15 mVpp output ripple at 300 mA, and compliance with thermal limits on standard 2-layer PCBs. Deviations below 1.76 µH risk instability and excessive current ripple.
Does LM3674MF-1.2 require external feedback resistors?
No, the LM3674MF-1.2 does not require external feedback resistors. As a fixed-output variant, it uses an internal resistor divider calibrated to deliver precisely 1.2 V at the VOUT pin. The FB pin is internally connected and inaccessible - unlike the adjustable LM3674-ADJ version, which requires external R1/R2 to set VOUT. This simplifies layout and eliminates resistor tolerance errors.
What is the minimum input voltage required for LM3674MF-1.2 to regulate 1.2 V?
The LM3674MF-1.2 requires a minimum input voltage of 2.7 V to initiate regulation and maintain 1.2 V output. Below this threshold, undervoltage lockout disables the device. At 2.7 V input, it delivers full 600 mA with acceptable efficiency; operation down to 2.7 V enables use across the entire discharge curve of a single Li-Ion cell (3.0 V–2.7 V), maximizing usable battery capacity.
How does the soft-start function work in LM3674MF-1.2?
The LM3674MF-1.2 implements hardware-based soft-start by progressively increasing the internal switch current limit in four discrete steps: 70 mA → 140 mA → 280 mA → 1020 mA (typical). This occurs only when EN transitions high after VIN reaches ≥2.7 V. The sequence limits inrush current into the 10 µF output capacitor, preventing input rail collapse and ensuring monotonic VOUT rise - critical for powering processors without reset glitches.
Can LM3674MF-1.2 be used in thermally demanding environments?
Yes, the LM3674MF-1.2 includes integrated thermal shutdown (125°C junction) and automatic recovery, making it suitable for enclosed handheld devices. On a 4-layer PCB with 130°C/W θJA, it sustains 600 mA continuously at 85°C ambient. For 2-layer boards (250°C/W), derating to 400 mA is recommended above 60°C ambient. Layout best practices - including thermal vias under the GND pad and copper pour - are essential for reliability.
LM3674MF-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
LM3674MF-1.2 FAQ
1.How can I place an order for LM3674MF-1.2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MF-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 LM3674MF-1.2 reliable?
The price and inventory of LM3674MF-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 LM3674MF-1.2 is usually 5 days.
3.What payment methods are accepted for LM3674MF-1.2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MF-1.2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MF-1.2?
LM3674MF-1.2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MF-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 LM3674MF-1.2?
For technical support, including LM3674MF-1.2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MF-1.2 requirements.
6.How does Aetrix verify that LM3674MF-1.2 is sourced from the original manufacturer or authorized distributors?
All LM3674MF-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 LM3674MF-1.2 meets industry standards.
7.What is the process for return or replacement of LM3674MF-1.2?
All LM3674MF-1.2 units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MF-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 LM3674MF-1.2 part is unused and in its original packaging.
Return procedure for LM3674MF-1.2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3674MF-1.2 Tags
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