LM2674M-3.3/NOPB

The LM2674 series of regulators are monolithic integrated circuits built with a LMDMOS process. These regulators provide all the active functions for a step-down (buck) switching regulator, capable of driving a 500-mA load current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, and an adjustable output version. Requiring a minimum number of external components, these regulators are simple to use and include patented internal frequency compensation and a fixed frequency oscillator. The LM2674 series operates at a switching frequency of 260 kHz, thus allowing smaller sized filter components than what is required with lower frequency switching regulators. Because of its very high efficiency (>90%), the copper traces on the printed-circuit board are the only heat sinking required. A family of standard inductors for use with the LM2674 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies using these advanced ICs. Also included in the data sheet are selector guides for diodes and capacitors designed to work in switch-mode power supplies. Other features include an ensured ±1.5% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is included, featuring typically 50-μA standby current. The output switch includes current limiting, as well as thermal shutdown for full protection under fault conditions.

Applications

• Simple High Efficiency (>90%) Step-Down (Buck) Regulators
• Efficient Preregulator for Linear Regulators
• Positive-to-Negative Converters

Key features

• Efficiency up to 96%
• Available in 8-Pin SOIC, PDIP, and 16-Pin WSON Packages
• Simple and Easy to Design With
• Requires Only 5 External Components
• Uses Readily Available Standard Inductors
• 3-V, 5-V, 12-V, and Adjustable Output Versions
• Adjustable Version Output Voltage Range: 1.21 V to 37 V
• ±1.5% Maximum Output Voltage Tolerance Over Line and Load Conditions
• Ensured 500-mA Output Load Current
• 0.25-Ω DMOS Output Switch
• Wide Input Voltage Range: 8 V to 40 V
• 260-kHz Fixed Frequency Internal Oscillator
• TTL Shutdown Capability, Low Power Standby Mode
• Thermal Shutdown and Current Limit Protection