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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