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Texas Instruments LM2677S-3.3
- Part No.:
- LM2677S-3.3
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2677S-3.3.pdf
- Description:
- IC REG BUCK 3.3V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:3,144
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Product details
Overview
LM2677S-3.3 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 3.3V output, 8V–40V input range, 260 kHz internal oscillator, 100 mΩ DMOS power switch, and ±2% output tolerance over full line/load/temperature. It delivers high-efficiency power conversion for industrial embedded systems requiring stable 3.3V rail generation from wide-input unregulated supplies.
For engineers reviewing the LM2677S-3.3 datasheet, LM2677S-3.3 pinout, LM2677S-3.3 application, or LM2677S-3.3 equivalent, key selection criteria include input voltage range compatibility, thermal performance in TO-263 (KTW) package, ON/OFF control interface, external sync capability (280–400 kHz), and fixed-output simplicity versus adjustable alternatives.
Technical Context
The LM2677S-3.3 implements a current-mode PWM buck controller with integrated 100 mΩ DMOS switch, fixed 3.3V feedback reference, and internal 260 kHz oscillator. It supports external synchronization (280–400 kHz) to align switching frequency across multiple rails or suppress EMI in sensitive RF subsystems.
Thermal protection includes built-in thermal shutdown and cycle-by-cycle current limiting (6.1–8.3 A typical limit). The ON/OFF pin enables low-quiescent (50 µA) standby mode, while the BOOST capacitor (0.01 µF) ensures full gate drive for minimal RDS(on) conduction loss.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% over −40°C to +125°C, 100 mA–5 A load, 8–40 V input - ensures stable logic supply for microcontrollers and FPGAs without external resistor divider. |
| Input Voltage Range | 8 V to 40 V - supports 12 V, 24 V, and 36 V industrial bus rails, including automotive battery transients up to 40 V. |
| Switch RDS(on) | 0.12 Ω typical - minimizes conduction loss at 5 A, enabling >90% efficiency at 12 VIN/3.3 VOUT. |
| Efficiency | 82% typical at 12 VIN, 5 A load - balances thermal dissipation and PCB area vs. linear regulators in high-current 3.3 V applications. |
| Quiescent Current | 4.2 mA operating, 50 µA standby - enables low-power system sleep modes without disabling upstream converters. |
| Oscillator Frequency | 260 kHz fixed (225–280 kHz range), sync-capable up to 400 kHz - allows predictable EMI filtering and avoids audio-band noise. |
| Current Limit | 6.1 A typical - provides robust short-circuit protection while sustaining 5 A continuous output under thermal limits. |
Pinout & Package
LM2677S-3.3 is packaged in DDPAK/TO-263 (Package Number KTW0007B), featuring exposed thermal pad (DAP) for enhanced heat dissipation. Mounting on ≥1.0064 in² copper area reduces θJA to 26°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 2) | Input Power Supply | Accepts 8–40 V unregulated input; requires local 0.1–0.47 µF ceramic + bulk capacitor for transient suppression. |
| VSW (Pin 1 & 4) | Switch Node | Drives external inductor; swings from VIN to ~−0.5 V during off-time; connects to BOOST capacitor (0.01 µF). |
| GND (Pin 3) | Power Ground | Common return for internal circuitry, switch, and feedback amplifier; must connect to low-inductance ground plane. |
| SYNC (Pin 5) | External Clock Input | AC-coupled TTL/CMOS clock (280–400 kHz); resets internal oscillator on rising edge; disables current-limit foldback when active. |
| FB (Pin 6) | Feedback Input | Internally tied to 3.3 V reference; direct connection to output required - no external resistors needed for fixed version. |
| ON/OFF (Pin 7) | Enable Control | Logic-level shutdown: ≤0.8 V = OFF (50 µA IQ), ≥1.4 V = ON; internal 20 µA pull-up and 7 V clamp. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 100 mΩ DMOS switch | Eliminates need for external MOSFET and driver, reducing BOM count and layout complexity for 5 A buck designs. |
| ±2% output tolerance over temperature | Guarantees 3.3 V compliance for 3.3 V logic families (e.g., ARM Cortex-M, SPI peripherals) without post-regulation. |
| External sync capability (280–400 kHz) | Enables deterministic ripple frequency placement for EMI-sensitive radio and communications equipment. |
| Thermal shutdown + current limiting | Provides autonomous fault recovery in overload or ambient overheating conditions without external protection circuitry. |
| 50 µA standby quiescent current | Supports low-power system states where only real-time clock or wake-on-interrupt functionality remains active. |
Applications
| Industrial PLC I/O Module | Telecom Line Card Power |
|---|---|
|
Use Scenario: Generating isolated 3.3 V logic supply from 24 V backplane in modular PLC chassis with space-constrained PCB layout. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 5 A continuous current to FPGA configuration memory, CAN transceivers, and ADC drivers. Use Value: Fixed 3.3 V output eliminates trimming resistors; TO-263 thermal pad enables conduction cooling without heatsink in sealed enclosures. |
Use Scenario: Providing clean 3.3 V rail for Ethernet PHYs and packet processors on telecom line cards with strict EMI requirements. IC Role / Device Role / Timing Role: Synchronized buck converter locked to system clock domain to avoid beat frequencies in spectral emissions. Use Value: External SYNC input allows precise ripple frequency positioning outside narrowband receiver bands, meeting FCC Class B limits. |
| Medical Diagnostic Imaging Subsystem | Automotive ADAS Camera Power |
|
Use Scenario: Powering high-speed ADCs and digital signal processors in portable ultrasound units with 12 V battery input. IC Role / Device Role / Timing Role: High-efficiency pre-regulator stepping down 12 V to 3.3 V before LDOs, minimizing thermal rise near sensitive analog front-ends. Use Value: 82% efficiency at 5 A reduces heat near temperature-sensitive imaging sensors; −40°C to +125°C rating supports extended operating range. |
Use Scenario: Supplying 3.3 V to CMOS image sensors and ISP SoCs in rear-view cameras exposed to under-hood temperatures. IC Role / Device Role / Timing Role: Robust buck converter handling 36 V load-dump transients while maintaining regulated 3.3 V output during cold-crank events. Use Value: 40 V absolute max input and thermal shutdown ensure reliability in automotive environments; ON/OFF pin enables camera sleep/wake coordination. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-3.3 | Higher 8 A current rating, same 3.3 V fixed output, identical pinout and package - but larger thermal footprint and higher cost. | Better suited for future-proofed designs requiring headroom beyond 5 A or higher peak loads. | Select LM2678-3.3 only if sustained >5 A load or higher transient margin is required; otherwise LM2677S-3.3 offers optimal cost/performance balance. |
| TPS54560B | Adjustable output (0.8–60 V), 60 V max input, 5 A, 2.5–6 MHz switching - no fixed 3.3 V option; requires external feedback resistors. | Preferred for multi-rail systems needing programmable outputs or higher input voltage tolerance (e.g., 48 V industrial buses). | Choose TPS54560B when design flexibility, higher input range, or frequency agility outweighs fixed-output simplicity and lower BOM count of LM2677S-3.3. |
Compared with LM2678-3.3 and TPS54560B, the LM2677S-3.3 delivers optimal integration for cost-sensitive, thermally constrained 5 A fixed 3.3 V applications - eliminating feedback components, supporting direct thermal pad mounting, and offering proven reliability in industrial temperature ranges without sacrificing efficiency or protection features.
Availability
LM2677S-3.3 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, telecom line card power, medical diagnostic imaging subsystems, and automotive ADAS camera power requiring stable component supply with long-term lifecycle assurance.
Supply support for LM2677S-3.3 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 engineers seeking fast, reliable, and low-component-count DC/DC buck regulator implementations in industrial, automotive, and communications equipment.
FAQ
What is the maximum input voltage rating for LM2677S-3.3?
The absolute maximum input voltage for LM2677S-3.3 is 45 V, with recommended operating range of 8 V to 40 V. This allows safe operation under automotive load-dump conditions (up to 40 V) and industrial 36 V bus transients. Exceeding 45 V risks permanent damage to the internal DMOS switch and control circuitry, as specified in the Absolute Maximum Ratings table of the SNVS077I datasheet.
Does LM2677S-3.3 require external feedback resistors?
No, LM2677S-3.3 does not require external feedback resistors. As a fixed-output variant, it integrates precision internal resistors to set the 3.3 V output. Pin 6 (FB) must be connected directly to the output node - no external divider is needed. This simplifies layout, improves accuracy, and eliminates resistor tolerance drift effects that affect adjustable regulators like LM2677-ADJ.
What thermal performance can be expected from LM2677S-3.3 in TO-263 package?
In the KTW (DDPAK/TO-263) package, LM2677S-3.3 achieves θJA = 26°C/W when mounted on 1.0064 in² of 1 oz. copper with 12 vias to inner layers. At 5 A output and 12 V input, junction temperature rise is ~130°C above ambient - requiring derating or forced airflow above 70°C ambient. Thermal shutdown activates at ~165°C junction temperature to prevent damage.
Can LM2677S-3.3 synchronize to an external clock?
Yes, LM2677S-3.3 supports external synchronization via Pin 5 (SYNC) over 280 kHz to 400 kHz. A TTL/CMOS clock signal must be AC-coupled using a 100 pF capacitor and 1 kΩ pull-down resistor. When synchronized, the internal oscillator is disabled and current-limit foldback is inactive - so short-circuit protection relies solely on cycle-by-cycle limiting without frequency reduction.
What is the standby current consumption of LM2677S-3.3?
LM2677S-3.3 draws 50 µA typical standby current when the ON/OFF pin is pulled to ≤0.8 V. This ultra-low quiescent state maintains regulation readiness while minimizing battery drain in always-on systems such as security sensors or remote telemetry nodes. The internal 20 µA pull-up ensures reliable turn-on when the pin is left floating or driven high.
LM2677S-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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)
LM2677S-3.3 FAQ
1.How can I place an order for LM2677S-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2677S-3.3 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 LM2677S-3.3 reliable?
The price and inventory of LM2677S-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2677S-3.3 is usually 5 days.
3.What payment methods are accepted for LM2677S-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2677S-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2677S-3.3?
LM2677S-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2677S-3.3 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 LM2677S-3.3?
For technical support, including LM2677S-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2677S-3.3 requirements.
6.How does Aetrix verify that LM2677S-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2677S-3.3 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 LM2677S-3.3 meets industry standards.
7.What is the process for return or replacement of LM2677S-3.3?
All LM2677S-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2677S-3.3, 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 LM2677S-3.3 part is unused and in its original packaging.
Return procedure for LM2677S-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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