Step-down regulator Texas Instruments LM2678 S-5.0, fixed 5 V output, input 8–40 V, TO-263 package

The Texas Instruments LM2678 S-5.0 is a step-down switching regulator that provides a fixed 5 V output from input voltages between 8 V and 40 V. Supplied in a TO-263 (D2PAK) power package, this buck regulator is designed to deliver regulated 5 V power for a range of electronic circuits and systems where a compact, high-efficiency converter is required. The device integrates the control and switching elements needed for a synchronous single-switch step-down topology and is suitable for designs that demand stable 5 V rails from higher-voltage sources.

Advantages

The LM2678 S-5.0 offers a wide input voltage range and a fixed, accurate 5 V output, reducing external component complexity for common 5 V designs. Its TO-263 package provides thermal performance and board-mount convenience for surface-mount assembly. The switching regulator topology enables higher efficiency compared with linear regulators when stepping down from elevated input voltages, which helps lower power dissipation and thermal stress in compact designs.

Suitable for

• Industrial power supplies and control modules requiring a stable 5 V rail
• Embedded systems and microcontroller power domains powered from 12 V or 24 V sources
• Automotive and vehicle electronics where wide input voltage tolerance is needed
• Compact electronic modules and PCB-mounted power converters

Key specifications

• Output voltage: fixed 5 V
• Input voltage range: 8 V to 40 V
• Package type: TO-263 (D2PAK) surface-mount power package
• Topology: step-down (buck) switching regulator
• Intended use: regulated DC power supply for electronic circuits

How to use

Integrate the LM2678 S-5.0 into a PCB layout following recommended application guidelines for input decoupling, switching node layout, and thermal vias to ensure stable operation and heat dissipation. Provide appropriate input and output capacitors and an inductor chosen to match the regulator's switching frequency and required output current. Observe manufacturer recommendations for layout near the switching node to minimize EMI and ensure reliable regulation at the 5 V output.

Usage recommendations

For best results, follow the device datasheet for component selection (capacitors, inductor, diode if required), thermal management, and PCB layout. Verify the regulator's thermal performance in your application and, if needed, add heatsinking or increased copper area on the PCB. Confirm input filtering and transient response meet system requirements when powering sensitive electronics.