LM2574N​ 0.5A Adjustable Output Voltage Step - Down Switching Regulator IC

Features

• 3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions

• Adjustable Version Output Voltage Range, 1.23 to 37 V ±4% max over Line and Load Conditions

• Guaranteed 0.5 A Output Current

• Wide Input Voltage Range: 4.75 to 40 V

• Requires Only 4 External Components

• 52 kHz Fixed Frequency Internal Oscillator

• TTL Shutdown Capability, Low Power Standby Mode

• High Efficiency

• Uses Readily Available Standard Inductors

• Thermal Shutdown and Current Limit Protection

Applications

• Simple and High–Efficiency Step–Down (Buck) Regulators

• Efficient Pre–regulator for Linear Regulators

• On–Card Switching Regulators

• Positive to Negative Converters (Buck–Boost)

• Negative Step–Up Converters

• Power Supply for Battery Chargers

Description

The LM2574 series of regulators are monolithic integrated circuits ideally suited for easy

and convenient design of a step–down switching regulator (buck converter).

All circuits of this series are capable of driving a 0.5 A load with excellent line and load regulation.

These devices are available in fixed output voltages of 3.3 V, 5.0 V, 12 V, 15 V, and an adjustable output version.

These regulators were designed to minimize the number of external components to simplify the power supply design.

Standard series of inductors optimized for use with the LM2574 are offered by several different inductor manufacturers.

Since the LM2574 converter is a switch–mode power supply,

its efficiency is significantly higher in comparison with popular three–terminal linear regulators,

especially with higher input voltages. In most cases, the power dissipated by the LM2574 regulator is so low,

that the copper traces on the printed circuit board are normally the only heatsink needed

and no additional heatsinking is required.

The LM2574 features include a guaranteed ±4% tolerance on output voltage

within specified input voltages and output load conditions, and ±10% on the oscillator frequency (±2% over 0°C to +125°C).

External shutdown is included, featuring 60 µA (typical) standby current.

The output switch includes cycle–by–cycle current limiting, as well as thermal shutdown for full protection under fault conditions.

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