My Inquiry
My Account
Texas Instruments LM3674MFX-2.8
- Part No.:
- LM3674MFX-2.8
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3674MFX-2.8.pdf
- Description:
- IC REG BUCK 2.8V 600MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,168
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM3674MFX-2.8 from Texas Instruments is a fixed-output 2.8 V, 600-mA synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered portable systems. It operates from 2.7 V to 5.5 V input, delivers up to 600 mA load current, features 2-MHz fixed-frequency PWM operation, internal soft-start, and 0.01 µA shutdown current - enabling compact, high-efficiency power delivery in space-constrained mobile phones and PDAs.
For engineers reviewing the LM3674MFX-2.8 datasheet, LM3674MFX-2.8 pinout, LM3674MFX-2.8 application, or LM3674MFX-2.8 equivalent, key selection criteria include its 2.8 V fixed output, SOT-23-5 package compatibility, 2-MHz switching frequency enabling small external components (2.2 µH inductor, 4.7 µF CIN, 10 µF COUT), and integrated synchronous rectification for >90% efficiency at mid-load.
Technical Context
The LM3674MFX-2.8 implements voltage-mode PWM control with input voltage feed-forward to ensure stable regulation across line and load variations. Its internal 0.5 V reference and feedback loop regulate output by modulating PFET on-time while maintaining constant 2 MHz switching frequency.
It integrates complementary PFET/NFET synchronous switches (RDSON(P) = 500 mΩ typ, RDSON(N) = 400 mΩ typ), thermal shutdown, cycle-by-cycle current limiting (1020 mA typ), and undervoltage lockout - all within a 5-pin SOT-23 package requiring only three external passive components for full operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.8 V ±4% - eliminates external resistor divider; enables direct replacement of LDOs in 2.8 V rail applications. |
| 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 margin for transient spikes. |
| Max Load Current | 600 mA - sufficient for baseband processors, RF transceivers, and display drivers in handheld devices. |
| Switching Frequency | 2 MHz (typical) - allows use of tiny 2.2 µH shielded inductors and low-ESR ceramic capacitors (CIN = 4.7 µF, COUT = 10 µF). |
| Shutdown Current | 0.01 µA (typical) - minimizes battery drain during system sleep modes in always-on portable electronics. |
| Feedback Reference | 0.5 V internal - sets output via internal resistor network; no external FB resistors required for fixed versions. |
| Thermal Protection | 125°C junction limit with automatic recovery - prevents damage during sustained overload or poor PCB thermal design. |
Pinout & Package
LM3674MFX-2.8 is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, with exposed pad for enhanced thermal performance. Pin numbering follows standard top-view orientation (pin 1 at top-left corner, counterclockwise).
| 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; must be ≥2.7 V before enable for reliable startup. |
| GND (Pin 2) | Ground Reference | Primary return path for input/output currents and IC bias; requires low-impedance PCB connection to minimize noise and thermal rise. |
| EN (Pin 3) | Digital Enable | Active-high logic input; device enabled when >1 V, shutdown when <0.4 V; 0.01 µA leakage ensures minimal standby drain. |
| FB (Pin 4) | Feedback Input | Internally connected to 2.8 V output divider; not user-accessible in fixed version - ties directly to internal reference node. |
| SW (Pin 5) | Switch Node | Drives external inductor; carries high di/dt switching current; requires short, low-inductance trace to minimize EMI and voltage overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Integrated NFET replaces Schottky diode - reduces conduction loss by ~300 mV, enabling >92% efficiency at 300 mA with 3.6 V input. |
| Internal Soft-Start | Gradual current limit ramp (70 → 140 → 280 → 1020 mA) - limits inrush into 10 µF output capacitor, preventing input rail collapse during startup. |
| 2-MHz Fixed-Frequency PWM | Enables consistent EMI profile and predictable filter design - avoids audible noise and simplifies compliance testing vs variable-frequency alternatives. |
| Current Limit Protection | 1020 mA typical peak switch current limit - protects internal FETs and external inductor during short-circuit or overload without latch-off. |
| Thermal Shutdown | 125°C junction trip with hysteresis - disables switching until die cools to ~110°C, allowing safe recovery without manual reset. |
Applications
| Mobile Phone Power Rail | PDA Core Voltage Supply |
|---|---|
Use Scenario: Powers application processor I/O or camera sensor interface in slim smartphone designs where board area is constrained. IC Role / Device Role / Timing Role: Primary buck regulator delivering stable 2.8 V from shared Li-Ion battery rail; operates in continuous conduction mode at 2 MHz. Use Value: Enables 2.2 µH inductor + dual 0805 ceramic capacitors - reduces total solution footprint to <12 mm² while maintaining >88% efficiency at 500 mA. | Use Scenario: Supplies 2.8 V to touch controller and flash memory in handheld PDA with aggressive thermal limits. IC Role / Device Role / Timing Role: High-efficiency point-of-load converter with thermal foldback; enters timed current-limit mode under sustained overload. Use Value: 0.01 µA shutdown current extends battery life in standby; internal synchronous FETs eliminate external diode heat dissipation. |
| MP3 Player Audio Codec Bias | Wireless LAN Module Supply |
Use Scenario: Provides clean, low-noise 2.8 V bias to stereo audio DAC/ADC in portable music players. IC Role / Device Role / Timing Role: Fixed-output buck converter with soft-start and low ripple (<15 mVpp) - minimizes audible artifacts during playback. Use Value: 2-MHz switching moves noise spectrum above audio band; ceramic input/output caps suppress broadband ripple without ferrite beads. | Use Scenario: Powers 2.8 V RF front-end in Wi-Fi/BT combo module where EMI must meet FCC Class B limits. IC Role / Device Role / Timing Role: Compact, high-frequency DC-DC source with controlled slew-rate SW node - reduces radiated emissions from inductor coupling. Use Value: SOT-23-5 package allows placement adjacent to RF IC; 2.2 µH shielded inductor contains magnetic flux, easing layout isolation. |
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 | 2.8 V fixed, 600 mA, 3-MHz switching, 2.05 V min VIN - higher frequency but narrower input range. | Requires ≥2.05 V input; unsuitable for deeply discharged Li-Ion (<2.7 V); better for 2.5 V+ rails. | Select when board space permits smaller 1 µH inductor and input voltage stays >2.05 V. |
| AP3012KTR-G1 | 2.8 V fixed, 500 mA, 1.5-MHz switching, 2.5 V min VIN - lower current rating and efficiency at light loads. | Limited to ≤500 mA loads; 1.5-MHz operation needs larger inductor (3.3 µH) for same ripple. | Choose for cost-sensitive designs where 500 mA max load and relaxed efficiency are acceptable. |
Compared with TPS62231DRYR and AP3012KTR-G1, LM3674MFX-2.8 uniquely balances 2.7 V minimum input (full Li-Ion support), 600 mA capability, and 2-MHz operation in SOT-23 - making it optimal for battery-powered systems requiring robust low-voltage start-up and compact filtering.
Availability
LM3674MFX-2.8 is available at Aetrix Electronics and suitable for mobile phones, PDAs, MP3 players, and wireless LAN modules requiring stable component supply with guaranteed long-term manufacturability and consistent electrical performance.
Supply support for LM3674MFX-2.8 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, embedded processing, and power management technologies, with decades of expertise in high-efficiency DC-DC conversion for portable electronics.
The LM3674 product line was designed specifically for ultra-compact, battery-operated devices demanding high efficiency at light-to-moderate loads - emphasizing minimal external component count, low quiescent current, and robust protection features in sub-3 mm packages.
FAQ
What is the recommended input and output capacitor configuration for LM3674MFX-2.8?
The LM3674MFX-2.8 requires a 4.7 µF X5R/X7R ceramic capacitor (6.3 V rating) placed close 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 2.7–5.5 V input and 0–600 mA load. Using Y5V dielectrics or undersized case sizes (e.g., 0402) risks capacitance loss due to DC bias and temperature drift - compromising ripple suppression and transient response in the LM3674MFX-2.8 application.
Does LM3674MFX-2.8 require external feedback resistors to set its output voltage?
No, LM3674MFX-2.8 does not require external feedback resistors. As a fixed-output variant, it integrates an internal resistor divider that references the 0.5 V internal bandgap to deliver precisely 2.8 V at the output. The FB pin is internally connected and not accessible for external adjustment - unlike the LM3674-ADJ version. This simplifies layout, eliminates resistor tolerance errors, and ensures consistent 2.8 V regulation without calibration in the LM3674MFX-2.8 design.
What thermal considerations apply to LM3674MFX-2.8 in a 2-layer PCB layout?
In a 2-layer PCB layout, LM3674MFX-2.8 has a junction-to-ambient thermal resistance (RθJA) of 250°C/W. At 600 mA load and 3.6 V input, power dissipation reaches ~180 mW - resulting in ~45°C junction rise above ambient. To maintain safe operation below 125°C, keep ambient ≤80°C and provide ≥1 cm² copper pour connected to the GND pin and exposed pad. Without adequate copper, thermal shutdown may activate under sustained load - a critical constraint verified in LM3674MFX-2.8 thermal characterization.
How does the soft-start function operate in LM3674MFX-2.8 during power-up?
The LM3674MFX-2.8 implements a four-step soft-start sequence triggered when EN transitions high after VIN exceeds 2.7 V. Switch current limit ramps from 70 mA → 140 mA → 280 mA → 1020 mA (typical), limiting inrush into the 10 µF output capacitor. With a 300 mA load, startup completes in ~350 µs; with 10 mA, it takes ~240 µs. This staged ramp prevents input rail sag and output overshoot - behavior confirmed in LM3674MFX-2.8 Figure 16 and 17 startup waveforms.
Can LM3674MFX-2.8 operate in 100% duty cycle for low-dropout conditions?
No, LM3674MFX-2.8 cannot operate in true 100% duty cycle. Only the adjustable LM3674-ADJ variant supports LDO-like operation near dropout by holding the PFET fully on. The fixed-output LM3674MFX-2.8 uses a dedicated internal feedback network that requires switching action for regulation - minimum input must exceed 2.8 V by at least the sum of PFET RDSON drop and inductor DCR drop. Attempting operation below ~2.95 V input will cause output collapse, as documented in LM3674MFX-2.8 recommended operating conditions.
LM3674MFX-2.8 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):
- 2.8V
- 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-2.8 FAQ
1.How can I place an order for LM3674MFX-2.8 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3674MFX-2.8 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-2.8 reliable?
The price and inventory of LM3674MFX-2.8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3674MFX-2.8 is usually 5 days.
3.What payment methods are accepted for LM3674MFX-2.8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3674MFX-2.8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3674MFX-2.8?
LM3674MFX-2.8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3674MFX-2.8 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-2.8?
For technical support, including LM3674MFX-2.8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3674MFX-2.8 requirements.
6.How does Aetrix verify that LM3674MFX-2.8 is sourced from the original manufacturer or authorized distributors?
All LM3674MFX-2.8 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-2.8 meets industry standards.
7.What is the process for return or replacement of LM3674MFX-2.8?
All LM3674MFX-2.8 units undergo pre-shipment inspection (PSI). If there is an issue with LM3674MFX-2.8, 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-2.8 part is unused and in its original packaging.
Return procedure for LM3674MFX-2.8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3674MFX-2.8 Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
