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Texas Instruments LM2677T-ADJ
- Part No.:
- LM2677T-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-7 Formed Leads
- Datasheet:
-
LM2677T-ADJ.pdf
- Description:
- IC REG BUCK ADJ 5A TO220-7
- Quantity:
- Payment:
- Shipping:
Inventory:1,080
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Product details
Overview
LM2677T-ADJ from Texas Instruments is a monolithic step-down (buck) DC/DC switching regulator IC with integrated 100-mΩ DMOS power switch, delivering up to 5 A output current, adjustable output voltage from 1.2 V to 37 V, and input voltage range of 8 V to 40 V. It operates at fixed 260 kHz or externally synchronized 280–400 kHz, enabling high-efficiency (>90%) power conversion in industrial and communications power supplies.
For engineers reviewing the LM2677T-ADJ datasheet, LM2677T-ADJ pinout, LM2677T-ADJ application, or LM2677T-ADJ equivalent, key selection criteria include its ±2% output voltage tolerance over line/load/temperature, 50-μA standby quiescent current in shutdown mode, thermal shutdown and current-limit protection, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2677T-ADJ implements a voltage-mode PWM control architecture with internal 260-kHz oscillator and external synchronization capability. Its feedback loop uses a two-stage, high-gain amplifier referenced to a precise 1.21-V internal bandgap, enabling stable regulation across 1.2–37 V via external resistor divider on FB pin.
It integrates a high-side DMOS switch with 0.14 Ω typical RDS(ON) at 25°C, bootstrapped gate drive via CB pin, and ON/OFF logic with 1.4-V threshold and 50-μA shutdown current. Thermal shutdown and cycle-by-cycle current limiting (6.1–8.3 A) provide robust fault protection without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5 A continuous - supports high-power loads such as FPGA core rails or motor drivers without external current boosting. |
| Input Voltage Range | 8 V to 40 V - accommodates wide-input industrial, automotive, and telecom supply rails without pre-regulation. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - set precisely via external resistor divider; enables single-part flexibility across multiple system voltages. |
| Feedback Reference | 1.21 V ±1.2% - ensures ±2% total output tolerance over full temperature and load range when using standard 1% resistors. |
| Switch RDS(ON) | 0.14 Ω (typ, 25°C) - minimizes conduction loss, enabling >90% efficiency at 5-A load with proper layout and component selection. |
| Quiescent Current | 6 mA (active), 50 μA (shutdown) - allows low-power standby operation in battery-backed or energy-sensitive systems. |
| Oscillator Frequency | 260 kHz (internal) or 280–400 kHz (external sync) - enables consistent EMI filtering and predictable ripple frequency placement in RF-sensitive designs. |
Pinout & Package
LM2677T-ADJ is packaged in TO-263 (KTW) - a 7-pin thermally enhanced surface-mount package with exposed die attach pad (DAP) for improved heat dissipation. Package dimensions: 10.16 mm × 8.69 mm × 4.83 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW | Switch node output | Drives external inductor; swings between VIN and ~−0.5 V during switching; requires short, low-inductance PCB trace to minimize ringing and EMI. |
| VIN | Power input | Connects to input supply and high-frequency bypass capacitor (CIN); path to GND must be shortest possible to reduce switching noise coupling. |
| CB | Bootstrap capacitor connection | Connects 0.01-μF ceramic capacitor to VSW; provides gate drive voltage >VIN for high-side MOSFET turn-on, ensuring low RDS(ON). |
| GND | Power ground | Common return for CIN, COUT, and internal circuits; must connect directly to large copper pour to minimize ground bounce and improve thermal performance. |
| SYNC | External clock input | Accepts TTL/CMOS clock (280–400 kHz); overrides internal oscillator; disables current limit foldback when active - requires ac-coupling via 100-pF + 1-kΩ to GND. |
| FB | Feedback sense input | High-impedance input (85 nA bias) referenced to 1.21 V; connects to resistor divider midpoint to set output voltage; sensitive to noise - route away from VSW and inductor. |
| ON/OFF | Enable control input | Logic-level enable: ≥1.4 V = ON, ≤0.8 V = OFF; internal 20-μA pullup; clamped to 7 V - allows direct microcontroller GPIO control without level shifting. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 100-mΩ DMOS switch | Eliminates need for external high-side MOSFET and driver, reducing BOM count and layout complexity while maintaining 5-A capability. |
| ±2% output voltage tolerance | Guaranteed over full line (8–40 V), load (100 mA–5 A), and temperature (−40°C to +125°C) - reduces need for post-regulation or trimming in production. |
| External sync capability (280–400 kHz) | Enables deterministic EMI frequency positioning and synchronization with other system clocks - critical for compliance in radio and comms equipment. |
| Thermal shutdown + current limiting | Provides autonomous protection against overload, short-circuit, and overheating without external sensing components or firmware intervention. |
| 50-μA shutdown quiescent current | Supports ultra-low-power sleep modes in portable or always-on systems - extends battery life or reduces standby power in AC-powered devices. |
Applications
| Industrial Power Supplies | Communications Equipment |
|---|---|
|
Use Scenario: 24-V industrial bus powering PLC I/O modules requiring stable 5-V or 3.3-V logic rails. IC Role / Device Role / Timing Role: Primary step-down regulator converting unregulated 24-V field supply to tightly regulated low-voltage logic rail. Use Value: Delivers 5 A at >90% efficiency with minimal heatsinking, leveraging wide 8–40 V input range to tolerate brownouts and surges. |
Use Scenario: Base station RF card requiring synchronized switching frequency to avoid interference with transceiver LO signals. IC Role / Device Role / Timing Role: Synchronized buck regulator whose 300-kHz switching frequency is locked to system master clock via SYNC pin. Use Value: Enables precise EMI spectrum placement outside sensitive IF bands, meeting FCC Part 15 Class B conducted emissions limits. |
| Battery Charger Pre-regulator | Test & Measurement Instrumentation |
|
Use Scenario: 48-V lithium-ion battery charger front-end supplying variable 12–20 V to downstream linear regulators. IC Role / Device Role / Timing Role: Adjustable preregulator setting intermediate voltage to minimize dropout and heat in subsequent LDO stages. Use Value: Adjustable 1.2–37 V output allows dynamic optimization of LDO headroom, improving overall system efficiency and thermal margin. |
Use Scenario: Portable oscilloscope requiring low-noise, stable analog supply rails (±15 V, +5 V) from a single 24-V battery pack. IC Role / Device Role / Timing Role: High-precision buck regulator powering ADC reference and op-amp bias rails with tight ±2% tolerance. Use Value: Guaranteed output accuracy eliminates need for calibration trim pots or post-regulation, reducing test time and component cost. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-5.0 | Fixed 5-V output; identical pinout, package, and 5-A rating; no FB/adjustability; 260-kHz only (no SYNC). | Suitable where fixed 5-V output suffices and synchronization is unnecessary - simplifies design but lacks voltage flexibility. | Select LM2678-5.0 only if output voltage is fixed and external clock sync is not required; avoids resistor divider design effort. |
| LM5115MH | External MOSFET controller (no integrated switch); supports >10 A with discrete FETs; 50–750 kHz programmable frequency; no integrated bootstrap diode. | Used in higher-current or higher-efficiency designs where thermal management or efficiency >94% is critical. | Choose LM5115MH when scaling beyond 5 A or requiring ultra-low quiescent current (<10 μA) and advanced protection features like hiccup mode. |
Compared with LM2678-5.0, LM2677T-ADJ trades fixed-output simplicity for full voltage adjustability and sync capability; compared with LM5115MH, it sacrifices scalability and ultra-low IQ for integration, reduced BOM, and ease of use in mid-power applications.
Availability
LM2677T-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, communications equipment, battery charger pre-regulators, and test instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2677T-ADJ 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-reliability power conversion ICs.
The LM2677 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease of use in non-isolated DC/DC buck applications, minimizing external component count while delivering high efficiency and robust protection.
FAQ
What is the maximum output voltage that can be set using the LM2677T-ADJ?
The LM2677T-ADJ supports an adjustable output voltage range from 1.2 V to 37 V, determined by the external resistor divider connected to the FB pin and referenced to its internal 1.21-V precision bandgap. This range is validated across the full operating temperature and load conditions specified in the datasheet, and the upper limit is constrained by the absolute maximum ratings of the internal switch and feedback circuitry.
Does the LM2677T-ADJ require an external bootstrap diode?
No, the LM2677T-ADJ does not require an external bootstrap diode. Its internal gate driver uses a capacitor (CB pin to VSW) for bootstrapping, and the IC integrates all necessary charge-pump circuitry to drive the high-side DMOS switch. A 0.01-μF ceramic capacitor is the only external component needed for the bootstrap network.
Can the LM2677T-ADJ operate with an input voltage lower than 8 V?
No - the LM2677T-ADJ has a minimum recommended input voltage of 8 V, and operation below this violates the Recommended Operating Conditions. Attempting to operate below 8 V may result in failure to start, unstable regulation, or undefined behavior due to insufficient headroom for the internal bias circuitry and switch drive.
How does the SYNC pin affect current limiting in the LM2677T-ADJ?
When the SYNC pin is actively driven with an external clock signal, current limit frequency foldback is disabled. As a result, the LM2677T-ADJ maintains full current limit (6.1–8.3 A) across temperature but loses foldback protection under sustained short-circuit conditions. Designers must ensure adequate thermal derating or add external protection if SYNC is used in fault-prone environments.
What package options are available for the LM2677T-ADJ, and which one is used in the 'T' suffix variant?
The LM2677T-ADJ uses the TO-263 (KTW) package - a 7-pin surface-mount thermally enhanced variant with an exposed die attach pad. Other variants include TO-220 (NDZ) and VSON (NHM), but the 'T' suffix specifically denotes the TO-263 package per TI's orderable addendum and device information table in the LM2677 datasheet.
LM2677T-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-7 Formed Leads
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 5A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-7
LM2677T-ADJ FAQ
1.How can I place an order for LM2677T-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2677T-ADJ 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 LM2677T-ADJ reliable?
The price and inventory of LM2677T-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2677T-ADJ is usually 5 days.
3.What payment methods are accepted for LM2677T-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2677T-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2677T-ADJ?
LM2677T-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2677T-ADJ 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 LM2677T-ADJ?
For technical support, including LM2677T-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2677T-ADJ requirements.
6.How does Aetrix verify that LM2677T-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2677T-ADJ 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 LM2677T-ADJ meets industry standards.
7.What is the process for return or replacement of LM2677T-ADJ?
All LM2677T-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2677T-ADJ, 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 LM2677T-ADJ part is unused and in its original packaging.
Return procedure for LM2677T-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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