LM2675MX-5.0/NOPB

The Texas Instruments LM2675MX-5.0/NOPB is a SIMPLE SWITCHER step-down voltage regulator built with LMDMOS process technology. It provides all active functions for a 1A buck switching regulator with fixed 5.0V output. The device requires only five external components and features patented internal frequency compensation and a fixed 260kHz oscillator. The high efficiency exceeding 90% means PCB copper traces provide sufficient heat sinking. Standard inductors from multiple manufacturers are compatible, greatly simplifying design. The device includes +-1.5% output voltage tolerance, external shutdown with 50uA standby current, and current limiting with thermal shutdown protection.

The LM2675MX-5.0/NOPB operates as a fixed-frequency buck converter with three key subsystems: 1) Oscillator and Control: The 260kHz internal oscillator sets the switching frequency. Voltage-mode control with patented internal compensation maintains output regulation. The duty cycle adjusts to maintain 5.0V output across input voltage and load variations. 2) Power Stage: The internal 0.25Ohm DMOS output switch alternately connects and disconnects the input voltage to the output inductor. When on, energy is stored in the inductor; when off, the catch diode provides a current path, transferring stored energy to the output capacitor and load. 3) Protection: Cycle-by-cycle current limiting prevents switch damage. Thermal shutdown disables the output when junction temperature exceeds the safe limit. The ON/OFF pin allows TTL-level shutdown with 50uA standby current.

• 5V power supply from 12V or 24V industrial bus
• Efficient pre-regulator before low-noise linear regulators
• Battery-powered equipment requiring 5V from 9V-24V sources
• Embedded system point-of-load regulation