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Texas Instruments LM2677SX-3.3/NOPB
- Part No.:
- LM2677SX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2677SX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A TO263
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM2677SX-3.3/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC voltage regulator with fixed 3.3-V output, integrated 100-mΩ DMOS power switch, 260-kHz internal oscillator, and ON/OFF control. It operates from 8 V to 40 V input and delivers ±2% output voltage tolerance over full line/load/temperature range. It is used in high-efficiency preregulators for telecom power systems and industrial embedded supplies.
For engineers reviewing the LM2677SX-3.3/NOPB datasheet, LM2677SX-3.3/NOPB pinout, LM2677SX-3.3/NOPB application, or LM2677SX-3.3/NOPB equivalent, key selection considerations include input voltage range (8–40 V), output current capability (5 A), thermal performance in TO-263 package, sync clock interface compatibility (280–400 kHz), and fixed-output configuration eliminating external feedback resistors.
Technical Context
The LM2677SX-3.3/NOPB implements a synchronous-buck topology using an internal high-side N-channel DMOS FET with 0.14 Ω typical RDS(ON) at 25°C. Its PWM controller uses a fixed 260-kHz ramp oscillator or accepts external synchronization up to 400 kHz - enabling precise ripple frequency positioning for EMI-sensitive radio equipment.
It integrates thermal shutdown, cycle-by-cycle current limiting (6.1–8.3 A), and an ON/OFF pin with 1.4-V threshold that reduces quiescent current to 50 μA in shutdown. The FB pin is internally connected to the 3.3-V output divider, eliminating external resistors and simplifying layout for fixed-output operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% over –40°C to 125°C junction temperature, 8–40 V input, 100 mA–5 A load - ensures stable logic rail generation without trimming. |
| Max Output Current | 5 A continuous - supports single-rail powering of FPGA I/O banks or multi-core microcontrollers without external current sharing. |
| Input Voltage Range | 8 V to 40 V - accommodates 12-V, 24-V, and 36-V industrial bus systems with headroom for transients. |
| Switching Frequency | 260 kHz internal oscillator (225–280 kHz over temp); externally synchronizable to 280–400 kHz - enables consistent EMI filtering and avoids sensitive IF bands. |
| RDS(ON) | 0.14 Ω typical at 25°C - minimizes conduction loss at 5 A (≤3.5 W dissipation), reducing heatsink requirements in TO-263 package. |
| Efficiency | 82% typical at 12 VIN/5 AOUT - achieves >90% system efficiency when paired with low-ESR output capacitors and shielded inductors. |
| Quiescent Current | 6 mA typical operating; 50 μA standby when ON/OFF pin < 0.8 V - extends battery life in always-on monitoring subsystems. |
Pinout & Package
LM2677SX-3.3/NOPB is housed in a 7-pin TO-263 (KTW) thermally enhanced surface-mount package (10.16 mm × 8.69 mm), with exposed DAP soldered to PCB ground plane for optimal thermal dissipation (RθJA = 26°C/W with 1.0064 in² copper).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| VSW | Switch node | Source of internal high-side DMOS FET; connects directly to inductor and Schottky diode cathode - requires short, low-inductance routing to minimize switching noise. |
| VIN | Power input | Drain of internal high-side FET; supplies input power and bootstraps CB via internal charge pump - must be decoupled with low-ESR capacitor placed adjacent to pin. |
| CB | Bootstrap capacitor terminal | Connects 0.01 μF ceramic capacitor to VSW; provides gate drive voltage > VIN to fully enhance internal FET - critical for low RDS(ON) and efficiency. |
| GND | Power ground | Common return for input/output capacitors, feedback network, and thermal pad - must tie to solid ground plane to limit noise coupling and improve thermal performance. |
| SYNC | Frequency synchronization input | Accepts TTL/CMOS clock (280–400 kHz); overrides internal oscillator - enables deterministic ripple placement for compliance testing in comms equipment. |
| FB | Feedback sense | Internally tied to 3.3-V output divider; no external resistors required - eliminates calibration drift and simplifies BOM for fixed-output use. |
| ON/OFF | Enable control | Logic-level input (1.4-V threshold); pulls high internally - allows microcontroller GPIO or system supervisor to sequence power without external pull-up. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 100-mΩ DMOS switch | Reduces conduction loss at 5 A, enabling compact thermal design in TO-263 without external MOSFETs or drivers. |
| Fixed 3.3-V output with internal feedback divider | Eliminates external resistor network, improving long-term output stability and reducing component count by two parts. |
| External sync clock interface (280–400 kHz) | Allows precise alignment of switching frequency to avoid interference with RF receivers or data converters in mixed-signal systems. |
| Thermal shutdown + current limiting | Protects against sustained overload or ambient overheating without requiring external circuitry - supports unattended industrial deployment. |
| 50-μA standby current | Enables low-power sleep modes in battery-backed controllers while retaining fast wake-up (<100 μs) via ON/OFF pin assertion. |
Applications
| Industrial PLC Power Supply | Telecom Line Card Preregulator |
|---|---|
|
Use Scenario: Provides clean 3.3-V rail for ARM-based controller, Ethernet PHY, and isolated I/O in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Primary buck regulator converting 24-V DC bus to regulated 3.3-V logic supply; operates at fixed 260-kHz frequency to simplify EMI filter design. Use Value: Delivers 5-A peak current during burst-mode communications while maintaining ±2% regulation across –25°C to 70°C ambient - eliminating need for post-regulation LDOs. |
Use Scenario: Generates 3.3-V supply for SERDES, clock buffers, and management MCU on carrier-grade line cards with strict ripple and transient response specs. IC Role / Device Role / Timing Role: High-current preregulator synchronized to system master clock (333 kHz) via SYNC pin to fix ripple spectrum and ease compliance testing. Use Value: Achieves <15 mVPP output ripple with 400-μF low-ESR output capacitor and supports 5-A load steps with <50-μs recovery - meeting Telcordia GR-63-CORE hold-up and transient requirements. |
| Automotive Body Control Module | Test Equipment Auxiliary Supply |
|
Use Scenario: Powers microcontroller, CAN transceiver, and sensor interfaces in 12-V automotive body electronics with cold-crank (6-V) and load-dump (40-V) resilience. IC Role / Device Role / Timing Role: Input-stage buck converter accepting wide 8–40 V range; ON/OFF pin controlled by vehicle ignition signal for automatic power sequencing. Use Value: Maintains regulation down to 8 V input and survives 45-V transients per ISO 7637-2; 50-μA shutdown current prevents battery drain during vehicle off-state. |
Use Scenario: Supplies 3.3-V/5-A rail for FPGA configuration, ADC reference, and digital I/O in benchtop test instruments requiring low-noise, fast-transient response. IC Role / Device Role / Timing Role: Fixed-output regulator with minimal external components - simplifies layout validation and accelerates prototype bring-up. Use Value: Delivers ±2% accuracy without trimming, supports 5-A dynamic loads with <100-mV undershoot, and enables board-level thermal monitoring via junction temperature range (–40°C to 125°C). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678SX-3.3/NOPB | Same pinout and 3.3-V fixed output, but rated for 3-A max output current and higher RDS(ON) (0.22 Ω typical). | Suitable for lower-power applications where 5-A capability is unnecessary; smaller thermal footprint. | Select when load current remains ≤3 A and cost reduction is prioritized over headroom. |
| TPS54560BQDDARQ1 | Automotive-grade 60-V input, 5-A buck with adjustable output, spread-spectrum clocking, and enhanced EMI performance. | Required for AEC-Q100 qualified designs or systems needing >40-V input tolerance and stricter EMI control. | Choose for automotive safety-critical modules or next-gen designs demanding wider VIN and advanced noise mitigation. |
Compared with LM2678SX-3.3/NOPB, the LM2677SX-3.3/NOPB delivers 67% higher current capacity and lower conduction loss; versus TPS54560BQDDARQ1, it offers simpler fixed-output implementation and lower cost but lacks automotive qualification and spread-spectrum features.
Availability
LM2677SX-3.3/NOPB is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and automotive body electronics requiring stable component supply, long-lifecycle support, and traceable sourcing.
Supply support for LM2677SX-3.3/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-reliability power conversion solutions.
The LM2677 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for easy, robust, high-efficiency DC/DC buck conversion using minimal external components in industrial, telecom, and automotive power systems.
FAQ
What is the maximum input voltage rating for LM2677SX-3.3/NOPB?
The absolute maximum input voltage for LM2677SX-3.3/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Operation above 40 V risks exceeding safe SOA limits under transient conditions. The device includes built-in protection against brief 45-V surges, though sustained operation beyond 40 V is not advised per TI's recommended operating conditions in SNVS077J Rev J.
Does LM2677SX-3.3/NOPB require external feedback resistors?
No, LM2677SX-3.3/NOPB does not require external feedback resistors. As a fixed 3.3-V output variant, its internal feedback divider is factory-trimmed and connected directly to the FB pin. This eliminates resistor tolerance errors and long-term drift, ensuring ±2% output accuracy across temperature and load without external components.
Can LM2677SX-3.3/NOPB synchronize to an external clock?
Yes, LM2677SX-3.3/NOPB supports external synchronization via its SYNC pin (Pin 5), accepting TTL/CMOS-compatible clocks from 280 kHz to 400 kHz. When driven, the internal 260-kHz oscillator is overridden, allowing precise control of switching frequency for EMI management - critical in radio and test equipment applications.
What thermal performance can be expected from LM2677SX-3.3/NOPB in TO-263 package?
In the TO-263 (KTW) package with 1.0064 in² copper area, LM2677SX-3.3/NOPB achieves RθJA = 26°C/W. At 5-A load and 12-V input, typical power dissipation is ~3.5 W, resulting in ~91°C junction rise above ambient - well within the –40°C to 125°C operating range when ambient stays below 34°C. Thermal pad soldering is mandatory for this rating.
How does the ON/OFF pin function on LM2677SX-3.3/NOPB?
The ON/OFF pin (Pin 7) enables logic-level control: voltage >1.4 V turns the regulator on; <0.8 V forces shutdown with 50-μA quiescent current. An internal 20-μA pull-up allows direct GPIO connection without external bias. The pin tolerates up to 6 V and includes a 7-V Zener clamp - supporting robust interfacing with microcontrollers and system supervisors.
LM2677SX-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 5A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-7)
LM2677SX-3.3/NOPB FAQ
1.How can I place an order for LM2677SX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2677SX-3.3/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 LM2677SX-3.3/NOPB reliable?
The price and inventory of LM2677SX-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2677SX-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2677SX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2677SX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2677SX-3.3/NOPB?
LM2677SX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2677SX-3.3/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 LM2677SX-3.3/NOPB?
For technical support, including LM2677SX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2677SX-3.3/NOPB requirements.
6.How does Aetrix verify that LM2677SX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2677SX-3.3/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 LM2677SX-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2677SX-3.3/NOPB?
All LM2677SX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2677SX-3.3/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 LM2677SX-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2677SX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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