LM2575-3.3WU

The LM2575 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, 12V, fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 1A 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 LM2575 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 LM2575 series. This feature greatly simplifies the design of switchmode 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 to 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
• Guaranteed 1A output current
• Wide input voltage range – 4V to 40V
• Wide output voltage range – 1.23V to 37V
• Requires only 4 external components
• 52kHz fixed frequency internal oscillator
• Low power standby mode IQ typically <200μA
• 80% efficiency (adjustable version typically >80%)
• Uses readily available standard inductors
• Thermal shutdown and current limit protection
• 100% electrical thermal limit burn-in