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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Texas Instruments LM2678S-12/NOPB

Name: LM2678S-12/NOPB
Brand: Texas Instruments
SKU: LM2678S-12/NOPB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM2678S-12/NOPB

Manufacturer:: Texas Instruments

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-8, D2PAK (7 Leads + Tab), TO-263CA

Datasheet:: LM2678S-12/NOPB.pdf

Description:: IC REG BUCK 12V 5A TO263

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Product details

Overview

LM2678S-12/NOPB from Texas Instruments is a monolithic step-down (buck) switching regulator IC delivering up to 5 A output current with fixed 12 V output, 8–40 V input range, 260 kHz fixed-frequency operation, and ±2% output voltage tolerance over full line/load/temperature. It integrates a 120 mΩ DMOS high-side switch and supports ON/OFF control for low-power standby.

For engineers reviewing the LM2678S-12/NOPB datasheet, LM2678S-12/NOPB pinout, LM2678S-12/NOPB application, or LM2678S-12/NOPB equivalent, key selection criteria include its 92% peak efficiency at 24 V_IN/5 A, thermal shutdown protection, 50 µA standby current, and compatibility with standard off-the-shelf inductors and Schottky diodes in TO-263-7 (KTW) package.

Technical Context

The LM2678S-12/NOPB implements a voltage-mode PWM controller with internal 260 kHz oscillator and integrated 120 mΩ DMOS high-side power switch. Its feedback loop senses output voltage directly at the FB pin (shorted to V_OUT for fixed 12 V version), enabling regulation without external resistors. The ON/OFF pin provides TTL-compatible enable control with 1.4 V threshold and 20 µA pull-up.

Thermal management relies on package-specific R_θJA: 56°C/W (KTW on 0.136 in² copper) or 26°C/W (KTW on 1.0064 in² copper). Protection features include cycle-by-cycle current limiting (6.1–8.3 A), thermal shutdown, and under-voltage lockout - all implemented within the monolithic die without external components.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 12 V ±2% (–40°C to +125°C junction), eliminating need for external feedback divider.
Input Voltage Range	8 V to 40 V DC - supports wide industrial and battery-derived supplies including 24 V nominal systems.
Max Output Current	5 A continuous - enables single-chip conversion for mid-power subsystems without external pass devices.
Switching Frequency	260 kHz fixed - allows use of compact, low-cost inductors (e.g., 10–22 µH) and reduces EMI compared to lower frequencies.
Peak Efficiency	92% at V_IN = 24 V, I_OUT = 5 A - achieved via low R_DS(ON) (0.12 Ω typ) DMOS switch and optimized gate drive.
Standby Current	50 µA max at T_J = 25°C - enables ultra-low-power shutdown in battery-backed or energy-sensitive applications.
Current Limit	6.1–8.3 A (temp-dependent) - provides robust short-circuit protection without external sensing resistors.
Operating Temp	–40°C to +125°C junction - qualified for automotive under-hood, industrial motor drives, and telecom power shelves.

Pinout & Package

LM2678S-12/NOPB is supplied in KTW (TO-263-7) package: thermally enhanced 7-pin surface-mount variant with exposed DAP (die attach pad) soldered to PCB ground plane for optimal thermal performance (R_θJA = 26°C/W with 1.0064 in² copper).

Pin/Terminal	Circuit Role	Design Meaning
1 (SW)	Switch output	Drain node of internal DMOS FET; connects to inductor and cathode of external Schottky diode - carries high di/dt switching current.
2 (VIN)	Input supply	Main power input (8–40 V); requires low-ESR bypass capacitor placed <5 mm from pin to minimize ringing and input ripple.
3 (CB)	Bootstrap capacitor	Connects to SW via 100 nF ceramic capacitor to generate gate drive voltage > VIN for full FET enhancement.
4 (GND)	Power ground	Primary return path for input/output capacitors and inductor; must be tied to DAP and system ground with low-inductance layout.
5 (NC)	No connect	Internally unconnected; leave floating or tie to GND per layout best practice - no electrical function.
6 (FB)	Feedback input	Shorted internally to V_OUT for 12 V fixed version; no external resistor network required - simplifies BOM and layout.
7 (ON/OFF)	Enable control	TTL-compatible digital input: ≥1.4 V = active regulation; ≤0.8 V = shutdown (50 µA I_Q); internal 20 µA pull-up enables open-circuit default ON.

Key Features

Feature	Design Value
Integrated 120 mΩ DMOS switch	Enables 5 A output without external MOSFETs; eliminates gate driver complexity and reduces board area vs discrete buck controllers.
Fixed 12 V output with ±2% tolerance	Guarantees precise rail generation across temperature and load - avoids calibration overhead in factory programming or field updates.
260 kHz fixed-frequency PWM	Stabilizes EMI spectrum for compliance testing; enables predictable filter design using standardized inductor families (e.g., Pulse PA434x, Coilcraft XAL5030).
ON/OFF pin with 50 µA standby	Supports system-level power sequencing and sleep modes - critical for battery-powered test equipment and portable instrumentation.
Built-in thermal shutdown & current limit	Provides autonomous fault recovery without external monitoring ICs - enhances reliability in unattended industrial controllers and remote sensors.
SIMPLE SWITCHER® design ecosystem	Validated reference designs, WEBENCH® Power Designer integration, and pre-characterized inductor libraries reduce time-to-functional prototype by >50%.

Applications

Industrial Motor Drive Power Supply	Automotive Body Control Module (BCM)
Use Scenario: Generating stable 12 V rail from 24 V truck battery for microcontroller, CAN transceivers, and solenoid drivers. IC Role / Device Role / Timing Role: Primary step-down regulator providing isolated, regulated 12 V output with fast transient response to handle load steps from 100 mA (idle) to 4.5 A (solenoid actuation). Use Value: 92% efficiency minimizes heat sink requirements in sealed enclosures; ON/OFF pin synchronizes with vehicle ignition state to eliminate parasitic drain.	Use Scenario: Powering infotainment head unit logic rails and display backlight drivers from 12 V battery with cold-crank immunity. IC Role / Device Role / Timing Role: Pre-regulator stepping down raw battery voltage (6–16 V during cranking) to clean 12 V intermediate bus before LDOs. Use Value: 8–40 V input range tolerates 25 V load-dump transients; ±2% output tolerance ensures consistent ADC reference and sensor biasing.
Telecom Remote Radio Unit (RRU)	Test & Measurement Bench Power
Use Scenario: Converting –48 V telecom supply to +12 V for FPGA, RF front-end bias, and clock distribution ICs in outdoor base stations. IC Role / Device Role / Timing Role: High-efficiency intermediate converter operating continuously at –40°C to +85°C ambient with forced-air cooling. Use Value: R_θJA = 26°C/W (with thermal pad) enables 5 A output without heatsink; 125°C max junction rating supports extended lifetime in sealed housings.	Use Scenario: Programmable bench supply channel delivering adjustable 12 V/5 A output with remote ON/OFF control via microcontroller. IC Role / Device Role / Timing Role: Core power stage controlled via GPIO-driven ON/OFF pin; feedback loop stabilized for dynamic load regulation (0–100% step in <100 µs). Use Value: 50 µA standby current enables zero-power "off" state; fixed 12 V output eliminates potentiometer drift and improves long-term calibration stability.

Industrial Motor Drive Power Supply

Automotive Body Control Module (BCM)

Use Scenario: Generating stable 12 V rail from 24 V truck battery for microcontroller, CAN transceivers, and solenoid drivers.

IC Role / Device Role / Timing Role: Primary step-down regulator providing isolated, regulated 12 V output with fast transient response to handle load steps from 100 mA (idle) to 4.5 A (solenoid actuation).

Use Value: 92% efficiency minimizes heat sink requirements in sealed enclosures; ON/OFF pin synchronizes with vehicle ignition state to eliminate parasitic drain.

Use Scenario: Powering infotainment head unit logic rails and display backlight drivers from 12 V battery with cold-crank immunity.

IC Role / Device Role / Timing Role: Pre-regulator stepping down raw battery voltage (6–16 V during cranking) to clean 12 V intermediate bus before LDOs.

Use Value: 8–40 V input range tolerates 25 V load-dump transients; ±2% output tolerance ensures consistent ADC reference and sensor biasing.

Telecom Remote Radio Unit (RRU)

Test & Measurement Bench Power

Use Scenario: Converting –48 V telecom supply to +12 V for FPGA, RF front-end bias, and clock distribution ICs in outdoor base stations.

IC Role / Device Role / Timing Role: High-efficiency intermediate converter operating continuously at –40°C to +85°C ambient with forced-air cooling.

Use Value: R_θJA = 26°C/W (with thermal pad) enables 5 A output without heatsink; 125°C max junction rating supports extended lifetime in sealed housings.

Use Scenario: Programmable bench supply channel delivering adjustable 12 V/5 A output with remote ON/OFF control via microcontroller.

IC Role / Device Role / Timing Role: Core power stage controlled via GPIO-driven ON/OFF pin; feedback loop stabilized for dynamic load regulation (0–100% step in <100 µs).

Use Value: 50 µA standby current enables zero-power "off" state; fixed 12 V output eliminates potentiometer drift and improves long-term calibration stability.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2678T-12/NOPB	Same silicon, TO-220-7 (NDZ) package - larger footprint, higher R_θJA (45–65°C/W), no thermal pad.	Preferred for through-hole prototyping or low-volume manual assembly where thermal mass compensates for lower efficiency.	Select when mechanical mounting constraints favor vertical TO-220 or when legacy PCBs lack KTW land pattern.
LM2596S-12	3 A rated, 150 kHz switching, 0.15 Ω R_DS(ON), no ON/OFF pin - lower current, slower frequency, fewer controls.	Suitable for cost-sensitive consumer electronics where 3 A suffices and thermal budget permits larger inductors.	Choose only if load current ≤3 A and 260 kHz EMI filtering is not required; verify thermal derating at full load.

Compared with LM2678T-12/NOPB, the LM2678S-12/NOPB delivers superior thermal performance in space-constrained layouts; versus LM2596S-12, it provides 67% higher current capacity, 73% faster switching, and active enable control - making it the preferred choice for industrial and telecom 5 A applications requiring reliability and design flexibility.

Availability

LM2678S-12/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, telecom remote radio units, and test & measurement equipment requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for LM2678S-12/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 technologies, with decades of expertise in high-reliability power conversion ICs.

The LM2678 series belongs to TI's SIMPLE SWITCHER® portfolio - designed specifically to simplify high-efficiency DC/DC buck regulator implementation using minimal external components while maintaining industrial-grade robustness and thermal performance.

FAQ

What is the maximum input voltage rating for LM2678S-12/NOPB?

The absolute maximum input voltage for LM2678S-12/NOPB is 45 V, but the recommended operating range is 8 V to 40 V DC. Operation above 40 V risks exceeding safe SOA limits during transients; sustained use beyond 40 V voids warranty and may cause premature failure. The 40 V upper limit ensures reliable operation across temperature and line variations while preserving 2 V margin below absolute max.

Does LM2678S-12/NOPB require an external feedback resistor network?

No, LM2678S-12/NOPB does not require external feedback resistors. As a fixed-output variant, its internal feedback divider is factory-trimmed to deliver precisely 12 V ±2%. Pin 6 (FB) is internally connected to the output, so users simply wire FB directly to the output capacitor - eliminating resistor matching errors, temperature drift, and BOM cost associated with adjustable versions.

How does the ON/OFF pin function on LM2678S-12/NOPB?

The ON/OFF pin (Pin 7) of LM2678S-12/NOPB enables hardware-controlled startup and shutdown: applying ≥1.4 V activates regulation; ≤0.8 V forces shutdown with 50 µA standby current. An internal 20 µA pull-up ensures default ON when left floating. Driving this pin from a microcontroller GPIO allows synchronized power sequencing - critical for systems requiring controlled boot-up or low-power sleep states.

What thermal performance can be expected from LM2678S-12/NOPB in KTW package?

In its KTW (TO-263-7) package, LM2678S-12/NOPB achieves R_θJA = 26°C/W when mounted on 1.0064 in² copper area with 12 thermal vias - enabling full 5 A output at +85°C ambient without a heatsink. With minimal copper (0.136 in²), R_θJA rises to 56°C/W, limiting continuous current to ~3.2 A at same ambient. Thermal pad (DAP) must be soldered to GND for specified performance.

Is LM2678S-12/NOPB compatible with WEBENCH® Power Designer?

Yes, LM2678S-12/NOPB is fully supported in TI's WEBENCH® Power Designer tool. Users can enter input/output specifications, select LM2678S-12/NOPB, and generate complete schematics, bill-of-materials, efficiency plots, thermal simulations, and PCB layout recommendations - including validated inductor models (e.g., Pulse PA4349.102NLT) and capacitor selections aligned with TI's reference designs.

LM2678S-12/NOPB 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:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 15V

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)

LM2678S-12/NOPB FAQ

1.How can I place an order for LM2678S-12/NOPB through Aetrix?

Please submit a Request for Quotation (RFQ) for LM2678S-12/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 LM2678S-12/NOPB reliable?

The price and inventory of LM2678S-12/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678S-12/NOPB is usually 5 days.

3.What payment methods are accepted for LM2678S-12/NOPB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678S-12/NOPB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM2678S-12/NOPB?

LM2678S-12/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM2678S-12/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 LM2678S-12/NOPB?

For technical support, including LM2678S-12/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678S-12/NOPB requirements.

6.How does Aetrix verify that LM2678S-12/NOPB is sourced from the original manufacturer or authorized distributors?

All LM2678S-12/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 LM2678S-12/NOPB meets industry standards.

7.What is the process for return or replacement of LM2678S-12/NOPB?

All LM2678S-12/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678S-12/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 LM2678S-12/NOPB part is unused and in its original packaging.

Return procedure for LM2678S-12/NOPB:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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