LM2576WU

The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. Fixed versions are available with a 3.3V, 5V, or 12V fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 3A load with excellent line and load regulation. These regulators are simple to use because they require a minimum number of external components and include internal frequency compensation and a fixed-frequency oscillator. The LM2576 series offers a high efficiency replacement for popular three-terminal adjustable linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. A standard series of inductors available from several different manufacturers are ideal for use with the LM2576 series. This feature greatly simplifies the design of switch-mode power supplies. The feedback voltage is guaranteed to ±2% tolerance for adjustable versions, and the output voltage is guaranteed to ±3% for fixed versions, within specified input voltages and output load conditions. The oscillator frequency is guaranteed to ±10%. External shutdown is included, featuring less than 200μA standby current. The output switch includes cycle-by-cycle current limiting and thermal shutdown for full protection under fault conditions.

Applications

• Simple High-Efficiency Step-Down (Buck) Regulator
• Efficient Pre-Regulator for Linear Regulators
• On-Card Switching Regulators
• Positive and Negative Converter (Inverting Buck-Boost)
• Isolated Flyback Converter using Minimum Number of External Components
• Negative Boost Converter

Key features

• 3.3V, 5V, 12V, and Adjustable Output Versions
• Voltage over Specified Line and Load Conditions: - Fixed Version: ±3% Max. Output Voltage - Adjustable Version: ±2% Max. Feedback Voltage
• Specified 3A Output Current
• Wide Input Voltage Range of 4V to 40V
• Wide Output Voltage Range of 1.23V to 37V
• Requires Only Four External Components
• 52kHz Fixed-Frequency Internal Oscillator
• Low Power Standby Mode |Q Typically <200μA
• 80% Efficiency (Adjustable Version Typically >80%)
• Uses Readily Available Standard Inductors
• Thermal Shutdown and Current Limit Protection
• 100% Electrical Thermal Limit Built-In