LM2679LD-3.3

Voltage Regulators - DC DC Switching Regulators Overview

The LM2679LD-3.3 is a SIMPLE SWITCHER® 5-A step-down voltage regulator manufactured by National Semiconductor. It operates with an input voltage range of 8V to 40V and provides a fixed 3.3V output. The device features a switching frequency of 260kHz and supports a maximum output current of 5A. It utilizes pulse width modulation control and includes adjustable current limit protection. The component is housed in a 14-VSON (6x5) package with a bare pad, suitable for surface mount installation across a junction temperature range of -40°C to 125°C.

Voltage Regulators - DC DC Switching Regulators Feature Summary

• Integrated SIMPLE SWITCHER design simplifies power supply development
• Adjustable current limit protects against overload conditions
• High efficiency operation through low on-resistance internal switch
• Fixed 3.3V output eliminates external feedback resistor requirements

Voltage Regulators - DC DC Switching Regulators Applications

• Point-of-load regulation for digital logic circuits
• Power supplies for embedded microcontroller systems
• Battery-powered equipment requiring efficient step-down conversion
• Industrial control modules operating from 12V or 24V rails

Voltage Regulators - DC DC Switching Regulators Procurement Notes

Verify the manufacturer designation as National Semiconductor, which was acquired by Texas Instruments. Confirm the specific suffix indicates the fixed 3.3V output variant within the LD package style. Check RoHS compliance status as older National Semiconductor parts may not meet current environmental standards. Ensure the 14-VSON package matches the target PCB footprint and thermal pad requirements for proper heat dissipation during high-current operation.

Voltage Regulators - DC DC Switching Regulators Selection Notes

Select this component when a fixed 3.3V output at up to 5A is required from an 8V to 40V input source. The 260kHz switching frequency allows for smaller passive components compared to lower-frequency regulators. Consider the thermal performance of the 14-VSON package if ambient temperatures approach the upper operational limit. Verify that the adjustable current limit feature aligns with the downstream load protection strategy.

Voltage Regulators - DC DC Switching Regulators Part Context

This part belongs to the SIMPLE SWITCHER family of monolithic DC/DC converters designed for ease of use. The LM2679 series integrates the switch, controller, and freewheeling diode functions into a single IC. The LD suffix typically denotes the VSON package configuration. This series replaces discrete solutions, reducing board space and component count while maintaining robust performance under varying line and load conditions.

Voltage Regulators - DC DC Switching Regulators Replacement Considerations

The LM2679S-3.3 serves as a pin-compatible alternative in the TO-263 package. For modern replacements, consider the LM2679S-3.3/NOPB for lead-free compliance. The LM22679 series offers similar functionality with added soft-start capabilities. Verify thermal resistance values when substituting packages to ensure adequate heat sinking.