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Texas Instruments LM3674MFX-ADJ/NOPB
- Part No.:
- LM3674MFX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MFX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3674MFX-ADJ/NOPB from Texas Instruments is a 2-MHz, 600-mA synchronous step-down DC-DC converter in SOT-23-5 package, designed for single Li-Ion battery-powered systems (2.7 V to 5.5 V input) delivering adjustable output voltages from 1 V to 3.3 V via external resistor divider. It integrates PFET/NFET switches, internal 0.5-V reference, soft-start, and thermal/overcurrent protection - used in mobile phones, MP3 players, and portable instruments.
For engineers reviewing the LM3674MFX-ADJ/NOPB datasheet, LM3674MFX-ADJ/NOPB pinout, LM3674MFX-ADJ/NOPB application, or LM3674MFX-ADJ/NOPB equivalent, key selection criteria include its 2-MHz fixed-frequency PWM operation, 0.01-µA shutdown current, synchronous rectification efficiency, FB pin voltage regulation at 0.5 V, and compatibility with minimal external components (2.2-µH inductor, 4.7-µF CIN, 10-µF COUT).
Technical Context
The LM3674MFX-ADJ/NOPB employs voltage-mode PWM control with input voltage feed-forward to achieve tight line and load regulation. Its internal 0.5-V reference sets output voltage via external R1/R2 divider on FB pin, enabling precise adjustment across 1–3.3 V range.
It operates in continuous conduction mode (CCM) up to 600 mA, using internal PFET (RDSON(P) = 380–500 mΩ) and NFET (RDSON(N) = 250–400 mΩ) switches with cycle-by-cycle current limiting (1020 mA typical) and thermal shutdown. Soft-start ramps switch current limit in steps (70/140/280/1020 mA) to limit inrush.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports full operation from single Li-Ion cell (3.0–4.2 V nominal) with margin for discharge and charging transients. |
| Max Output Current | 600 mA - sustained load capability across full input/output voltage range and temperature (−30°C to 125°C). |
| Switching Frequency | 2 MHz (typical) - enables use of small 2.2-µH shielded inductors and ceramic capacitors (CIN = 4.7 µF, COUT = 10 µF). |
| Feedback Reference | 0.5 V - sets output voltage via external resistor divider (VOUT = 0.5 × (1 + R1/R2)); enables 1 V to 3.3 V adjustment with <±4% VFB tolerance. |
| Shutdown Current | 0.01 µA (typical) - ultra-low quiescent draw during EN = low, critical for battery runtime in standby modes. |
| Internal Protection | Thermal shutdown + current overload protection - automatically disables switching under fault conditions to prevent damage. |
| Efficiency Peak | Up to 94% - achieved at mid-load (e.g., 300 mA, VOUT = 1.5 V, VIN = 3.6 V) due to synchronous rectification eliminating diode loss. |
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 (NOPB suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Connects to input filter capacitor (4.7 µF ceramic); accepts 2.7–5.5 V; supplies internal circuitry and PFET switch. |
| GND (Pin 2) | Ground Reference | Primary return path for power, feedback, and enable circuits; must be low-impedance connection to minimize noise and voltage drop. |
| EN (Pin 3) | Digital Enable | Active-high logic input; device enabled when >1 V, shutdown when <0.4 V; 0.01 µA input current allows direct MCU GPIO control. |
| FB (Pin 4) | Analog Feedback | Connects to resistor divider (R1/R2) from VOUT to GND; regulates output by holding voltage at 0.5 V ±4%. |
| SW (Pin 5) | Switch Node | Drives external inductor; connects internally to PFET drain and NFET source; requires short, low-inductance PCB trace to minimize EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Integrated NFET replaces Schottky diode, reducing conduction loss and enabling >90% efficiency at light-to-moderate loads. |
| 2-MHz Fixed-Frequency PWM | Enables compact BOM with 2.2-µH inductor and avoids AM/FM band interference; stable over temperature (1.6–2.6 MHz range). |
| Adjustable Output (1–3.3 V) | Configured via external R1/R2 divider; 200-kΩ R2 recommended to balance noise immunity and bias current (2.5 µA at 0.5 V). |
| Internal Soft-Start | Ramps current limit in four discrete steps (70/140/280/1020 mA), limiting inrush into output capacitor without external components. |
| Low Shutdown Current | 0.01 µA typical draw in shutdown extends battery life in always-on portable devices with periodic wake-up cycles. |
Applications
| Mobile Phones | MP3 Players |
|---|---|
Use Scenario: Powering baseband processor core voltage (1.2–1.5 V) from a single Li-Ion cell (3.0–4.2 V). IC Role / Device Role / Timing Role: Primary buck regulator providing regulated, low-noise supply with fast transient response to CPU load changes. Use Value: 2-MHz switching minimizes inductor size (<2.5 mm² footprint), while 0.01-µA shutdown preserves battery during sleep states. | Use Scenario: Generating 1.8-V or 3.3-V supply for audio DAC, flash memory, and display driver in handheld music players. IC Role / Device Role / Timing Role: Adjustable-output DC-DC converter supporting multiple rail requirements from one compact solution. Use Value: External resistor programming enables flexible voltage scaling without redesign; synchronous operation maintains >92% efficiency at 100–400 mA loads. |
| Portable Hard Disk Drives | Digital Still Cameras |
Use Scenario: Supplying 2.5-V or 3.3-V motor driver and controller ICs in 1.8-inch HDDs powered by Li-Ion battery. IC Role / Device Role / Timing Role: High-current (up to 600 mA), low-ripple power stage with thermal protection during burst write operations. Use Value: Integrated current limiting (1020 mA typ) and thermal shutdown prevent latch-up during motor stall or short-circuit events. | Use Scenario: Providing 1.5-V or 2.8-V supply to image sensor interface and ISP in compact digital cameras. IC Role / Device Role / Timing Role: Efficient, low-noise buck converter with fast load transient recovery for sensor pixel readout bursts. Use Value: 2-MHz operation reduces output ripple amplitude and improves PSRR at high frequencies critical for analog sensor performance. |
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 | 2.25-MHz fixed frequency, 600-mA output, 0.6-V reference, smaller 1.0-mm² DSBGA package. | Higher switching frequency enables smaller inductors but tighter layout constraints; lacks LDO-mode dropout support. | Preferred where board space is critical and input-to-output differential is ≥0.6 V; not suitable for near-100% duty-cycle LDO operation. |
| AP3012KTR-G1 | 1.5-MHz frequency, 600-mA output, 0.6-V reference, no integrated NFET (external diode required). | Lower efficiency (~85% peak) due to asynchronous rectification; higher thermal dissipation at full load. | Selected for cost-sensitive designs where efficiency >90% is non-critical and thermal margin exists; requires external Schottky diode. |
Compared with LM3674MFX-ADJ/NOPB, TPS62231DRYR offers higher integration density but forfeits low-dropout capability, while AP3012KTR-G1 trades efficiency and component count for lower unit cost - making LM3674MFX-ADJ/NOPB optimal for balanced performance, thermal safety, and design simplicity in Li-Ion portable systems.
Availability
LM3674MFX-ADJ/NOPB is available at Aetrix Electronics and suitable for mobile phones, MP3 players, and portable hard disk drives requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3674MFX-ADJ/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 leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-efficiency DC-DC conversion.
The LM3674 product line delivers compact, high-frequency synchronous buck converters optimized for battery-powered portable electronics - emphasizing low quiescent current, small solution size, and robust protection for consumer-grade reliability.
FAQ
What is the minimum input voltage required for LM3674MFX-ADJ/NOPB to regulate a 1.5-V output at 300 mA?
The minimum input voltage is calculated as VIN,MIN = ILOAD × (RDSON(P) + RINDUCTOR) + VOUT. Using typical RDSON(P) = 440 mΩ and a 2.2-µH inductor with DCR = 200 mΩ, VIN,MIN ≈ 300 mA × (0.44 Ω + 0.2 Ω) + 1.5 V = 1.692 V. However, per datasheet operating conditions, LM3674MFX-ADJ/NOPB requires ≥2.7 V input for guaranteed regulation - below which undervoltage lockout disables operation.
Can LM3674MFX-ADJ/NOPB operate in 100% duty-cycle mode, and what is its impact on output ripple?
Yes, LM3674MFX-ADJ/NOPB supports low-dropout (LDO) mode at near-100% duty cycle when VIN is close to VOUT. In this mode, the PFET remains fully enhanced and no switching occurs. Output ripple increases to ~25 mV peak-to-peak due to absence of filtering by the LC network - confirmed in datasheet Section 8.1.2.
What are the recommended values and types for the external R1 and R2 resistors in the LM3674MFX-ADJ/NOPB feedback network?
R2 should be 200 kΩ to maintain 2.5 µA divider current (0.5 V / 200 kΩ), balancing noise immunity and power loss. R1 is calculated as R1 = R2 × (VOUT / 0.5 − 1). For VOUT = 1.5 V, R1 = 200 kΩ × (3 − 1) = 400 kΩ. Use 1% metal-film resistors; avoid carbon composition due to tempco and noise.
How does the soft-start function of LM3674MFX-ADJ/NOPB behave during power-up, and can it be disabled?
Soft-start activates automatically when EN transitions high after VIN ≥2.7 V, ramping switch current limit in four steps (70/140/280/1020 mA) over ~240–350 µs depending on load and COUT. It cannot be disabled - no external capacitor or pin control is provided; it is an internal, unalterable feature per datasheet Section 8.1.1.
What thermal derating applies to LM3674MFX-ADJ/NOPB when mounted on a 2-layer PCB?
On a 2-layer board, RθJA = 250°C/W. At TA = 85°C, maximum power dissipation drops to 160 mW (per Table 6.5). For 600-mA operation at VOUT = 1.5 V and VIN = 3.6 V, power loss ≈ (3.6 − 1.5) × 0.6 × (1 − 0.93) ≈ 89 mW - within safe limits. Layout must include thermal vias under the exposed pad (if present) and copper pour to sustain full load.
LM3674MFX-ADJ/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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 3.3V
- 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-ADJ/NOPB FAQ
1.How can I place an order for LM3674MFX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MFX-ADJ/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 LM3674MFX-ADJ/NOPB reliable?
The price and inventory of LM3674MFX-ADJ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3674MFX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM3674MFX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MFX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MFX-ADJ/NOPB?
LM3674MFX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MFX-ADJ/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 LM3674MFX-ADJ/NOPB?
For technical support, including LM3674MFX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MFX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM3674MFX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3674MFX-ADJ/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 LM3674MFX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM3674MFX-ADJ/NOPB?
All LM3674MFX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MFX-ADJ/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 LM3674MFX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM3674MFX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3674MFX-ADJ/NOPB Tags
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