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Texas Instruments LM3674MF-ADJ/NOPB
- Part No.:
- LM3674MF-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MF-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:9,250
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Product details
Overview
LM3674MF-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, PDAs, and portable instruments requiring compact, high-efficiency power conversion.
For engineers reviewing the LM3674MF-ADJ/NOPB datasheet, LM3674MF-ADJ/NOPB pinout, LM3674MF-ADJ/NOPB application, or LM3674MF-ADJ/NOPB equivalent, key selection criteria include its 2-MHz fixed-frequency PWM operation, 0.01-µA shutdown current, internal synchronous rectification, 600-mA load capability, and FB-pin-based adjustable output regulation with 0.5-V reference voltage.
Technical Context
The LM3674MF-ADJ/NOPB employs voltage-mode PWM control with input voltage feed-forward to achieve tight line and load regulation. Its functional block includes a 2-MHz oscillator, error amplifier referenced to 0.5 V, PWM comparator, soft-start ramp generator, and integrated PFET/NFET power stage.
It operates exclusively in PWM mode across its full 0–600 mA load range and enters shutdown when EN < 0.4 V, reducing quiescent current to 0.01 µA. The device supports low-dropout (100% duty-cycle) operation near VIN ≈ VOUT and features cycle-by-cycle current limiting at 1020 mA (typical) with thermal shutdown at 125°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports direct connection to single Li-Ion cell (fully charged to depleted) without pre-regulation. |
| Output Current | Up to 600 mA - delivers full rated load across entire input range and ambient temperature (–30°C to 85°C). |
| Switching Frequency | 2 MHz (typical) - enables use of small 2.2-µH inductor and 10-µF/4.7-µF ceramic capacitors, minimizing board area. |
| Feedback Reference | 0.5 V - sets output via external R1/R2 divider; allows precise adjustment from 1 V to 3.3 V with minimal divider current (2.5 µA at R2 = 200 kΩ). |
| Shutdown Current | 0.01 µA (typical) - minimizes battery drain during system sleep; EN pin logic-low disables all internal circuitry. |
| Internal FETs | PFET RDSON = 500 mΩ max, NFET RDSON = 400 mΩ max - enables high efficiency (>90% at mid-load) without external rectifier. |
| Protections | Thermal shutdown, current limit (830–1200 mA), undervoltage lockout - ensures robust operation under fault conditions without external components. |
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); must be ≥2.7 V for enable; supplies internal bias and PFET switch. |
| GND (Pin 2) | Ground Reference | System ground return for all analog and power circuits; requires low-impedance PCB connection to minimize noise. |
| EN (Pin 3) | Digital Enable | Active-high logic input; device enabled when >1 V, disabled when <0.4 V; 0.01 µA input current enables 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; no internal divider in ADJ version. |
| SW (Pin 5) | Switch Node | Drives external inductor; carries high di/dt switching current; requires short, low-inductance PCB trace and proper thermal pad layout. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Integrated NFET replaces Schottky diode - eliminates 0.3–0.5 V forward drop, improving efficiency by 5–12% at low VOUT. |
| Internal Soft-Start | Gradual current limit ramp (70 → 140 → 280 → 1020 mA) - prevents inrush current and output overshoot during startup. |
| Adjustable Output | 0.5-V FB reference with external R1/R2 - supports any output from 1 V to 3.3 V using standard 1% resistors; R2 = 200 kΩ optimizes noise immunity vs. power. |
| High-Frequency Operation | 2-MHz fixed PWM frequency - reduces inductor size to 2.2 µH and enables fast transient response (<10 µs recovery). |
| Low IQ Shutdown | 0.01 µA shutdown current - extends battery life in always-on portable devices; compatible with deep-sleep MCU states. |
Applications
| Mobile Phone Power Rail | PDA Core Voltage Supply |
|---|---|
Use Scenario: Powers application processor I/O or memory interface at 1.8 V from 3.6-V Li-Ion battery. IC Role / Device Role / Timing Role: Primary buck regulator providing stable, low-noise core voltage with fast load transient response. Use Value: 2-MHz switching and ceramic output capacitor deliver <25 mV ripple and <5 µs recovery from 100→300 mA step load. | Use Scenario: Supplies 1.2-V DSP core in handheld PDA with dynamic voltage scaling. IC Role / Device Role / Timing Role: Adjustable-output buck converter enabling software-controlled VDD scaling via FB resistor network. Use Value: 0.5-V reference and 200-kΩ R2 allow precise 1.2-V setting with ±1% accuracy over temperature and line variation. |
| MP3 Player Audio Codec | Portable Instrument Sensor Bias |
Use Scenario: Generates clean 3.3-V supply for audio DAC and headphone amplifier in battery-powered MP3 player. IC Role / Device Role / Timing Role: High-efficiency, low-ripple power source decoupled from noisy digital subsystems. Use Value: Synchronous rectification and 10-µF X5R output capacitor achieve >92% efficiency at 300 mA and <15 mV p-p ripple. | Use Scenario: Provides stable 2.5-V bias for precision analog sensor front-end in portable multimeter. IC Role / Device Role / Timing Role: Low-drift, low-noise adjustable regulator with thermal protection for sensitive measurement circuitry. Use Value: 0.0010%/mA load regulation and 0.083%/V line regulation ensure <10 mV output shift across full battery discharge (4.2 V → 2.7 V). |
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, 300-mA output, 0.6-V reference, smaller 2-mm × 2-mm WSON package | Better suited for space-constrained ultra-portables; lower max current limits peak power delivery | Select when board area is critical and load ≤300 mA; verify FB divider compatibility with 0.6-V reference. |
| AP3012KTR-G1 | 1.5-MHz switching, 600-mA output, 1.25-V reference, requires external diode, larger SOT-23-6 package | Lower efficiency due to external Schottky; higher dropout at light loads | Choose only if cost sensitivity outweighs efficiency and board space; confirm thermal derating for 600-mA continuous operation. |
Compared with TPS62231DRVR and AP3012KTR-G1, the LM3674MF-ADJ/NOPB offers superior efficiency via synchronous rectification, tighter regulation with its 0.5-V reference, and proven 2-MHz stability in noise-sensitive audio and RF sections - making it optimal for mid-power portable systems where thermal headroom and ripple performance are prioritized.
Availability
LM3674MF-ADJ/NOPB is available at Aetrix Electronics and suitable for mobile phones, PDAs, and portable instrumentation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3674MF-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 ICs, with decades of expertise in high-efficiency DC-DC conversion for portable electronics.
The LM3674 product line was engineered specifically for space- and battery-constrained handheld devices, emphasizing minimal external component count (3 passive parts), ultra-low shutdown current, and robust operation across wide input voltage and temperature ranges.
FAQ
What is the minimum input voltage required for LM3674MF-ADJ/NOPB to regulate a 1.5-V output?
The minimum input voltage for LM3674MF-ADJ/NOPB to sustain 1.5 V output depends on load current and component losses: VIN,MIN = ILOAD × (RDSON(P) + RINDUCTOR) + VOUT. With typical PFET RDSON of 500 mΩ and a 200-mΩ inductor, at 300 mA load, VIN,MIN ≈ 1.5 V + 0.3 A × 0.7 Ω = 1.71 V - but per datasheet, stable operation requires VIN ≥2.7 V to ensure proper bias and control loop functionality. Below 2.7 V, the device may not start or maintain regulation.
Can LM3674MF-ADJ/NOPB operate in 100% duty-cycle mode, and what is its impact on output ripple?
Yes, LM3674MF-ADJ/NOPB supports 100% duty-cycle (LDO-like) operation when VIN is close to VOUT, turning the PFET fully on without switching. In this mode, output ripple increases to approximately 25 mV p-p due to absence of filtering by the LC network - verified in datasheet Figure 17. This behavior is intentional for dropout support but should be evaluated against system noise requirements before deployment.
How is the feedback resistor divider calculated for LM3674MF-ADJ/NOPB to set a 2.8-V output?
For LM3674MF-ADJ/NOPB, VOUT = VFB × (1 + R1/R2), where VFB = 0.5 V. To achieve 2.8 V, solve 2.8 = 0.5 × (1 + R1/R2) → R1/R2 = 4.6. Using R2 = 200 kΩ (recommended for noise immunity), R1 = 4.6 × 200 kΩ = 920 kΩ. Standard 1% values: R1 = 910 kΩ, R2 = 200 kΩ yield VOUT ≈ 2.775 V - within typical tolerance. Always verify with actual layout parasitics and temperature drift.
Does LM3674MF-ADJ/NOPB require an external compensation network?
No, LM3674MF-ADJ/NOPB uses internal frequency compensation optimized for standard 2.2-µH inductors and 10-µF ceramic output capacitors. The datasheet confirms stable operation without external compensation components across all recommended operating conditions. Adding external compensation may destabilize the control loop and is not supported.
What thermal considerations apply to LM3674MF-ADJ/NOPB in a 2-layer PCB design?
In a 2-layer PCB, LM3674MF-ADJ/NOPB has RθJA = 250°C/W. At 600 mA and 3.6-V input delivering 1.8-V output, power dissipation is ~0.36 W. Junction temperature rise = 0.36 W × 250°C/W = 90°C. With 25°C ambient, TJ ≈ 115°C - below 125°C max but near thermal limit. TI recommends using thermal vias under the exposed pad and copper pours to reduce RθJA; for sustained 600-mA loads, a 4-layer board (RθJA = 130°C/W) is strongly advised.
LM3674MF-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
LM3674MF-ADJ/NOPB FAQ
1.How can I place an order for LM3674MF-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MF-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 LM3674MF-ADJ/NOPB reliable?
The price and inventory of LM3674MF-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 LM3674MF-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM3674MF-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MF-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MF-ADJ/NOPB?
LM3674MF-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MF-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 LM3674MF-ADJ/NOPB?
For technical support, including LM3674MF-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MF-ADJ/NOPB requirements.
6.How does Aetrix verify that LM3674MF-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3674MF-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 LM3674MF-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM3674MF-ADJ/NOPB?
All LM3674MF-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MF-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 LM3674MF-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM3674MF-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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