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Texas Instruments LM2677SDX-ADJ
- Part No.:
- LM2677SDX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2677SDX-ADJ.pdf
- Description:
- IC REG BUCK ADJ 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,508
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Product details
Overview
LM2677SDX-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 across an adjustable output range of 1.2 V to 37 V. It operates from 8 V to 40 V input, achieves up to 92% efficiency, and features ±2% output voltage tolerance over full line/load/temperature conditions.
For engineers reviewing the LM2677SDX-ADJ datasheet, LM2677SDX-ADJ pinout, LM2677SDX-ADJ application, or LM2677SDX-ADJ equivalent, key selection criteria include its adjustable output architecture, internal 260 kHz fixed-frequency oscillator, external sync capability (280–400 kHz), ON/OFF control with 50 µA standby current, and thermal shutdown protection.
Technical Context
The LM2677SDX-ADJ implements a current-mode PWM control architecture with internal ramp compensation and cycle-by-cycle current limiting. Its feedback loop uses a precision 1.21 V reference (typical VFB = 1.21 V) referenced to the FB pin, enabling accurate output regulation via external resistor divider.
It integrates a high-side DMOS switch with 0.12 Ω typical RDS(ON), supports continuous conduction mode (CCM) operation, and includes built-in thermal shutdown, overcurrent protection, and undervoltage lockout. The SYNC pin allows external clock injection to override the internal 260 kHz oscillator - critical for EMI-sensitive communications and radio equipment where spectral positioning matters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5 A maximum continuous load current - supports high-power industrial and telecom pre-regulator applications without external current boosting. |
| Input Voltage Range | 8 V to 40 V - enables direct operation from unregulated 12 V, 24 V, or 36 V bus systems common in automotive, industrial, and battery-powered equipment. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - configured via external resistive divider on FB pin; supports custom rail generation beyond standard 3.3 V/5 V/12 V fixed versions. |
| Feedback Reference | 1.21 V ±2% - high-accuracy internal reference ensures tight output regulation even under wide temperature (-40°C to +125°C) and load variations. |
| Switch RDS(ON) | 0.12 Ω typical - low conduction loss enables >90% efficiency at 5 A, reducing thermal stress and simplifying heatsink requirements. |
| Quiescent Current | 4.2 mA operating / 50 µA standby - ultra-low standby draw when ON/OFF pin is grounded, ideal for battery-backed or energy-conscious systems. |
| Oscillator Frequency | 260 kHz fixed (internal) or 280–400 kHz synchronized - enables consistent ripple frequency control for predictable EMI filtering and compliance testing. |
Pinout & Package
The LM2677SDX-ADJ is packaged in the 7-lead DDPAK/TO-263 (package code KTW), featuring an exposed thermal pad (DAP) that must be soldered to PCB ground for optimal thermal performance (θJA as low as 26 °C/W with 7.4× copper area).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 2) | Input supply connection | Accepts 8–40 V unregulated DC; requires local 0.1–0.47 µF ceramic + bulk capacitor for transient suppression and EMI reduction. |
| VSW (Pin 1) | Switch node output | Drives external inductor; swings between VIN and ~−0.5 V (Schottky diode drop); high dv/dt node requiring careful layout. |
| CBOOST (Pin 3) | Bootstrap capacitor terminal | Connects to VSW via 0.01 µF/50 V ceramic capacitor to generate gate drive voltage >VIN for full MOSFET enhancement. |
| GND (Pin 4) | Power and signal ground | Common return for all internal circuitry; must connect to low-impedance ground plane to minimize noise coupling and ensure stability. |
| SYNC (Pin 5) | External clock input | Accepts TTL/CMOS-compatible square wave (280–400 kHz); ac-coupled via 100 pF cap + 1 kΩ pull-down for reliable oscillator reset. |
| FB (Pin 6) | Feedback input | Senses output voltage via resistor divider; internal 1.21 V reference sets VOUT = 1.21 × (1 + R1/R2); sensitive to noise - keep trace short and away from VSW. |
| ON/OFF (Pin 7) | Enable/disable control | Logic-level input: <0.8 V = OFF (50 µA IQ), >2.0 V = ON; internal 20 µA pull-up allows open-circuit default ON operation. |
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 tolerance over full conditions | Ensures stable system rail accuracy without post-production trimming - critical for ADC references, sensor biasing, and analog subsystems. |
| External synchronization (280–400 kHz) | Enables precise ripple frequency alignment across multiple converters in dense PCB layouts, simplifying EMI filter design and certification. |
| Thermal shutdown + current limiting | Provides robust fault protection during overload, short-circuit, or inadequate heatsinking - prevents catastrophic failure in field-deployed equipment. |
| 50 µA standby quiescent current | Supports always-on subsystems (e.g., real-time clocks, wake-on-LAN circuits) with minimal battery drain in backup or low-power modes. |
Applications
| Industrial Power Pre-regulation | Telecom DC-DC Conversion |
|---|---|
|
Use Scenario: Converting 24 V or 36 V intermediate bus to 5 V or 12 V for downstream point-of-load regulators in PLCs and motor drives. IC Role / Device Role / Timing Role: Primary buck regulator providing high-current, high-efficiency pre-regulation before LDOs or secondary converters. Use Value: Delivers 5 A at >90% efficiency with minimal thermal rise, reducing cooling requirements and improving system MTBF. |
Use Scenario: Generating stable 3.3 V or 5 V rails for baseband processors, FPGAs, and RF front-end ICs in cellular infrastructure equipment. IC Role / Device Role / Timing Role: Synchronized buck controller ensuring deterministic switching frequency to avoid interference with sensitive RF bands. Use Value: External SYNC capability enables fixed 350 kHz operation - placing ripple harmonics outside critical LTE/5G receive bands. |
| Battery Charger Front-end | Ruggedized Embedded Systems |
|
Use Scenario: Regulating variable-input voltage from lead-acid or LiFePO₄ battery packs (10–32 V) to constant 5 V/3 A for charging management ICs. IC Role / Device Role / Timing Role: Input-stage buck converter handling wide VIN range and load transients during charge termination cycles. Use Value: Wide 8–40 V input range accommodates battery voltage sag and surge; ON/OFF pin enables charger enable/disable sequencing. |
Use Scenario: Powering mission-critical controllers in transportation, energy, or defense systems requiring extended temperature (-40°C to +125°C) operation. IC Role / Device Role / Timing Role: High-reliability DC/DC regulator with built-in thermal shutdown and current limit for harsh-environment deployment. Use Value: Guaranteed operation across full junction temperature range and robust fault protection reduce need for redundant supervision circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678SDX-ADJ | Higher 8 A current rating; identical pinout, package, and feature set; 0.08 Ω RDS(ON) vs. 0.12 Ω. | Preferred where future-proofing for >5 A loads or lower thermal margin is required; same PCB layout but higher cost and larger inductor. | Select LM2678SDX-ADJ only if peak load exceeds 5 A or thermal headroom is constrained - otherwise LM2677SDX-ADJ offers optimal cost/performance balance. |
| TPS54560BQPWPRQ1 | Automotive-grade (AEC-Q100); 60 V max input; 5 A; integrated soft-start and current sense; different pinout and package (HTSSOP-20). | Required for automotive infotainment or ADAS modules needing qualification; not drop-in compatible due to pin count, footprint, and control interface differences. | Choose TPS54560BQPWPRQ1 only for automotive applications demanding AEC-Q100 compliance - LM2677SDX-ADJ remains optimal for industrial/commercial use. |
Compared with LM2678SDX-ADJ and TPS54560BQPWPRQ1, the LM2677SDX-ADJ delivers best-in-class efficiency and simplicity for non-automotive 5 A buck conversion, with identical mechanical fit to the LM2678 but lower cost, and significantly simpler layout than the HTSSOP-based TPS54560BQPWPRQ1.
Availability
LM2677SDX-ADJ is available at Aetrix Electronics and suitable for industrial power pre-regulation, telecom DC-DC conversion, and ruggedized embedded systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2677SDX-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 high-efficiency, medium-power DC/DC applications where minimal external components and rapid time-to-market are critical.
FAQ
What is the minimum input voltage required for stable operation of the LM2677SDX-ADJ?
The LM2677SDX-ADJ requires a minimum input voltage of 8 V to ensure proper internal biasing and regulation. Below this threshold, the device may fail to start or exhibit unstable output voltage due to undervoltage lockout activation. This specification is guaranteed across the full −40°C to +125°C junction temperature range and applies regardless of output voltage setting or load condition.
Can the LM2677SDX-ADJ be synchronized to an external clock, and what are the valid frequency limits?
Yes, the LM2677SDX-ADJ supports external synchronization via its SYNC pin (Pin 5). Valid input frequencies range from 280 kHz to 400 kHz - strictly above the internal oscillator's maximum of 280 kHz to prevent erratic reset behavior. The external clock must be TTL- or CMOS-compatible and ac-coupled using a 100 pF capacitor and 1 kΩ pull-down resistor to ground, as specified in the official TI datasheet SNVS077I.
What is the recommended boost capacitor value and voltage rating for the LM2677SDX-ADJ?
The LM2677SDX-ADJ requires a 0.01 µF ceramic capacitor rated for at least 50 V between the BOOST (Pin 3) and VSW (Pin 1) terminals. This value is explicitly validated by Texas Instruments for reliable gate overdrive and minimal conduction loss across all operating conditions. Using a lower capacitance or voltage rating risks incomplete MOSFET turn-on and reduced efficiency or thermal overstress.
How does the ON/OFF pin function on the LM2677SDX-ADJ, and what is its threshold voltage?
The ON/OFF pin (Pin 7) provides logic-level enable/disable control for the LM2677SDX-ADJ. It activates the regulator when pulled above 2.0 V and disables it - reducing quiescent current to 50 µA - when pulled below 0.8 V. An internal 20 µA pull-up current source allows open-circuit operation as default ON. Exceeding the absolute maximum 6 V rating risks permanent damage to the input protection clamp.
What thermal performance can be expected from the LM2677SDX-ADJ in the DDPAK/TO-263 package?
In the DDPAK/TO-263 (KTW) package, the LM2677SDX-ADJ achieves a junction-to-ambient thermal resistance (θJA) as low as 26 °C/W when mounted on a PCB with 1.0064 in² copper area and 12 thermal vias - per TI's AN-1187 layout guidelines. Without enhanced copper, θJA rises to 56 °C/W. The exposed DAP must be soldered directly to the PCB ground plane to realize these values; insufficient thermal connection will cause premature thermal shutdown at ≤3 A loads.
LM2677SDX-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- 14-VSON (5x6)
LM2677SDX-ADJ FAQ
1.How can I place an order for LM2677SDX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2677SDX-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 LM2677SDX-ADJ reliable?
The price and inventory of LM2677SDX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2677SDX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2677SDX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2677SDX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2677SDX-ADJ?
LM2677SDX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2677SDX-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 LM2677SDX-ADJ?
For technical support, including LM2677SDX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2677SDX-ADJ requirements.
6.How does Aetrix verify that LM2677SDX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2677SDX-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 LM2677SDX-ADJ meets industry standards.
7.What is the process for return or replacement of LM2677SDX-ADJ?
All LM2677SDX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2677SDX-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 LM2677SDX-ADJ part is unused and in its original packaging.
Return procedure for LM2677SDX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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