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Texas Instruments LM2677SX-12
- Part No.:
- LM2677SX-12
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2677SX-12.pdf
- Description:
- IC REG BUCK 12V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,878
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Product details
Overview
LM2677SX-12 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 12V 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 in industrial power supplies and battery-charged systems.
For engineers reviewing the LM2677SX-12 datasheet, LM2677SX-12 pinout, LM2677SX-12 application, or LM2677SX-12 equivalent, key selection criteria include its 5A continuous load capability, thermal shutdown protection, ON/OFF control with 50 μA standby current, external sync clock support (280–400 kHz), and compatibility with standard off-the-shelf inductors and Schottky diodes.
Technical Context
The LM2677SX-12 implements a current-mode PWM buck controller with integrated 100 mΩ DMOS power switch and internal 260 kHz oscillator. Its feedback loop uses a two-stage high-gain amplifier referenced to an internal 1.21 V bandgap, enabling precise regulation of the 12V output across 100 mA–5A loads.
It supports external synchronization via TTL/CMOS-compatible clock (280–400 kHz) applied to the SYNC pin, disabling internal frequency foldback during sync mode. Thermal shutdown, cycle-by-cycle current limiting (6.1–8.75 A), and ON/OFF control with 0.8–2.0 V threshold provide robust system-level protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V, ±2% tolerance over −40°C to +125°C junction temperature, 15–40 V input, 100 mA–5 A load. |
| Input Voltage Range | 8 V to 40 V DC - supports wide-range unregulated inputs including 12 V, 24 V, and 36 V industrial rails. |
| Continuous Output Current | 5 A - enables single-regulator solutions for mid-power embedded systems without parallel devices. |
| Switch RDS(ON) | 0.12–0.225 Ω - low conduction loss ensures >90% efficiency at 24 VIN/12 VOUT/5 A operation. |
| Oscillator Frequency | 260 kHz (internal fixed) or 280–400 kHz (external sync) - determines inductor size, ripple frequency, and EMI profile. |
| Standby Quiescent Current | 50 μA - enables ultra-low-power shutdown in battery-backed or energy-sensitive applications. |
| Thermal Shutdown Threshold | Internally activated above +165°C junction temperature - protects against sustained overload or poor heatsinking. |
Pinout & Package
LM2677SX-12 is packaged in the 7-lead DDPAK/TO-263 (package code KTW), featuring an exposed die attach pad (DAP) for enhanced thermal performance. The DAP must be soldered to a PCB ground plane for optimal junction-to-ambient thermal resistance (as low as 26°C/W with 7.4× package-area copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW (Pin 1) | Switch Node | Drives external inductor; swings between VIN (switch ON) and ~−0.5 V (switch OFF via Schottky clamp); requires low-inductance layout. |
| VIN (Pin 2) | Power Input | Supplies bias and load power; must be bypassed with ≥10 μF low-ESR capacitor placed adjacent to pin. |
| CBOOST (Pin 3) | Bootstrap Capacitor Terminal | Connects to VSW via 0.01 μF/50 V ceramic capacitor to gate-drive the internal MOSFET above VIN. |
| GND (Pin 4) | Power Ground | Primary return path for switch current and IC bias; requires low-impedance connection to DAP and system ground plane. |
| SYNC (Pin 5) | External Clock Input | Accepts 280–400 kHz TTL/CMOS clock (AC-coupled via 100 pF + 1 kΩ to GND); disables internal oscillator and current-limit foldback. |
| FB (Pin 6) | Feedback Input | Direct connection to 12 V output (no external resistors); monitors regulated output via internal 1.21 V reference amplifier. |
| ON/OFF (Pin 7) | Enable Control | Logic-level shutdown: ≤0.8 V = OFF (50 μA IQ); ≥2.0 V = ON; internal 20 μA pull-up and 7 V clamp. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 100 mΩ DMOS Power Switch | Eliminates need for external high-side MOSFET and driver, reducing BOM count and layout complexity for 5 A buck designs. |
| ±2% Output Voltage Tolerance | Ensures stable 12 V rail without post-regulation for sensitive analog or digital loads across full temperature and load range. |
| External Sync Capability (280–400 kHz) | Enables deterministic EMI filtering and synchronized multi-rail switching in communication equipment and RF subsystems. |
| 50 μA Standby Quiescent Current | Supports low-power sleep modes in portable or always-on systems without compromising fast wake-up response. |
| Current Limit & Thermal Shutdown | Provides self-protecting operation under short-circuit, overload, or inadequate heatsinking-no external fault management required. |
Applications
| Industrial Power Supply | Battery Charger Pre-regulator |
|---|---|
|
Use Scenario: 24 V bus-powered PLC I/O module requiring clean, regulated 12 V for logic and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24 V input to isolated 12 V output with tight load regulation and ripple suppression. Use Value: Delivers 5 A continuously at >92% efficiency, minimizing thermal stress and eliminating need for secondary linear regulators. |
Use Scenario: Lead-acid battery charger using 36 V unregulated adapter input to generate stable 12 V for charging circuitry. IC Role / Device Role / Timing Role: High-current pre-regulator stepping down variable adapter voltage before linear charge control stage. Use Value: Maintains ±2% output accuracy across 15–40 V input range, ensuring consistent charge voltage despite input fluctuations. |
| Communications Equipment | RF Transceiver Power Rail |
|
Use Scenario: Base station subsystem requiring tightly controlled 12 V supply for FPGA configuration and interface logic. IC Role / Device Role / Timing Role: Synchronized buck converter locked to system clock to avoid beat frequencies in signal processing paths. Use Value: External SYNC pin enables precise 300 kHz ripple placement outside critical IF bands, simplifying EMI filter design. |
Use Scenario: Microwave radio transceiver needing low-noise 12 V rail for PA bias and LO synthesis circuits. IC Role / Device Role / Timing Role: Primary DC/DC converter with minimized output ripple (<50 mVPP) via optimized COUT and layout. Use Value: 260 kHz fixed frequency allows predictable ripple harmonics; low RDS(ON) reduces thermal coupling into sensitive RF sections. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-12 | Higher 8 A current rating, same 12 V fixed output, identical pinout and package (KTW), but 300 kHz oscillator and higher quiescent current (10 mA vs. 4.2 mA active). | Suitable for higher-load systems where headroom beyond 5 A is required; not drop-in for thermally constrained layouts due to increased power dissipation. | Select LM2678-12 only when >5 A continuous output or higher transient surge capability is mandatory. |
| TPS54560B | Adjustable 3.5–60 V input, 0.8–60 V output, 5 A, 100 kHz–2.5 MHz programmable frequency, integrated soft-start and current sense, but no fixed 12 V variant. | Requires external resistor divider and compensation network; better suited for designs needing flexibility or higher switching frequencies. | Choose TPS54560B when adjustable output, wider VIN, or programmable frequency outweighs simplicity of fixed-output LM2677SX-12. |
Compared with LM2678-12 and TPS54560B, the LM2677SX-12 offers the simplest implementation for fixed 12 V/5 A applications-requiring zero external feedback components, minimal external passives, and proven thermal behavior in TO-263 packages-making it ideal for cost- and time-sensitive industrial power designs.
Availability
LM2677SX-12 is available at Aetrix Electronics and suitable for industrial power supplies, battery charger pre-regulators, communications equipment, and RF transceiver power rails requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2677SX-12 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 ease-of-use in non-isolated DC/DC buck applications, emphasizing minimal external components, robust protection, and compatibility with standard magnetics.
FAQ
What is the maximum input voltage rating for the LM2677SX-12?
The absolute maximum input voltage for the LM2677SX-12 is 45 V, but the recommended operating range is 8 V to 40 V DC. Operation above 40 V risks exceeding safe operating area limits and may trigger overvoltage protection or cause permanent damage. Always maintain input transients within this window using appropriate front-end clamping or filtering.
Does the LM2677SX-12 require external feedback resistors to set its output voltage?
No, the LM2677SX-12 does not require external feedback resistors. It is a fixed-output variant with internal resistor divider configured for 12 V, so the FB pin (Pin 6) connects directly to the output. This eliminates tuning error, improves stability, and reduces component count compared to adjustable versions like LM2677-ADJ.
Can the LM2677SX-12 be synchronized to an external clock, and what are the timing constraints?
Yes, the LM2677SX-12 supports external synchronization via its SYNC pin (Pin 5) with a TTL/CMOS-compatible clock signal ranging from 280 kHz to 400 kHz. The clock must be AC-coupled using a 100 pF capacitor and terminated with a 1 kΩ resistor to ground. Note that current-limit foldback is disabled during sync mode, so short-circuit protection relies solely on cycle-by-cycle limiting.
What thermal performance can be expected from the LM2677SX-12 in the DDPAK/TO-263 package?
In the KTW (DDPAK/TO-263) package, the LM2677SX-12 achieves a junction-to-ambient thermal resistance (θJA) as low as 26°C/W when mounted on 1.0064 in² of 1 oz. copper with 12 thermal vias. With adequate PCB copper area and heatsinking, it sustains 5 A continuous output at ambient temperatures up to +85°C without derating.
Is the LM2677SX-12 RoHS-compliant and lead-free?
Yes, the LM2677SX-12 is RoHS-compliant and lead-free per TI's standard packaging specifications. It meets JEDEC J-STD-020 moisture sensitivity level (MSL) 3 requirements and is qualified for lead-free reflow soldering profiles up to 260°C peak temperature (wave soldering: 4 sec at 260°C).
LM2677SX-12 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:
- 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):
- 12V
- 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-12 FAQ
1.How can I place an order for LM2677SX-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2677SX-12 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-12 reliable?
The price and inventory of LM2677SX-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2677SX-12 is usually 5 days.
3.What payment methods are accepted for LM2677SX-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2677SX-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2677SX-12?
LM2677SX-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2677SX-12 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-12?
For technical support, including LM2677SX-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2677SX-12 requirements.
6.How does Aetrix verify that LM2677SX-12 is sourced from the original manufacturer or authorized distributors?
All LM2677SX-12 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-12 meets industry standards.
7.What is the process for return or replacement of LM2677SX-12?
All LM2677SX-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2677SX-12, 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-12 part is unused and in its original packaging.
Return procedure for LM2677SX-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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