onsemi LM2575T-5G

LM2575T-5G Product Summary

The LM2575T-5G, designed by onsemi, is a monolithic step-down (buck) switching regulator IC that provides a fixed 5V output at up to 1A of continuous load current. Packaged in the industry-standard TO-220-5 form factor, it targets power supply engineers seeking efficiency, flexibility, and simplicity in converting voltages from higher DC rails to 5V logic or subcircuits. The LM2575 series, to which this device belongs, is also available in other fixed output voltages and as an adjustable version (1.23V to 37V). The LM2575T-5G was engineered to reduce component count and PCB complexity in power supply applications without compromising protection or regulation fidelity.

Main Attributes of the LM2575T-5G

The LM2575T-5G incorporates a robust collection of modern switching regulator features. Its key attributes include:

Fixed 5V output version (other voltage variants and adjustable version available)

Guaranteed 1A output current capability

Wide input voltage acceptance: 4.75V to 40V, accommodating automotive, industrial, and consumer rail requirements

Compact design: Only four external components required for a functional buck regulator

High efficiency operation, typically exceeding linear regulators, especially at higher input voltages

±4% output voltage tolerance and ±10% oscillator frequency stability; tight regulation ensures predictable system performance

Internal fixed 52kHz switching frequency oscillator for consistent transient performance

TTL-compatible external shutdown (ON/OFF) feature, allowing for reduced standby current (80μA typ)

Comprehensive protection suite: cycle-by-cycle current limiting and thermal shutdown for fault tolerance

Moisture Sensitivity Level (MSL) 1; Pb-free and RoHS-compliant packaging

LM2575T-5G Electrical Specs and Performance Metrics

Operating with an input as high as 40V, the LM2575T-5G offers stable 5V output regulation within ±4% tolerance across varied inputs and up to the rated 1A load. The device employs a fixed-frequency switching architecture, maintaining a 52kHz oscillator frequency (±10% accuracy). Critical electrical parameters include:

Quiescent current is low, minimizing system losses during standby or low-load conditions.

Under fault/overload, the oscillator frequency drops to 18kHz, reducing average power dissipation and protecting the device.

Output current limiting is featured via cycle-by-cycle control.

Thermal protection ensures device survival if the junction temperature exceeds the rated maximum.

The drop-out voltage is lower than typical linear regulators, preserving efficiency at higher currents.

Use Cases for the LM2575T-5G

Thanks to its flexible electrical characteristics, the LM2575T-5G is widely suited for:

Simple, high-efficiency step-down power supplies for microcontroller, ASIC, or logic circuits

Pre-regulators feeding traditional linear regulators, improving overall power chain efficiency

On-card DC/DC converters in distributed systems or industrial modules

Positive to negative conversion and negative step-up circuits when configured appropriately

Charging circuits where precise current control is not required but tight voltage regulation is beneficial

Design Recommendations for LM2575T-5G Integration

The integration of the LM2575T-5G into a power solution is streamlined by its simplicity yet requires careful attention to peripheral component selection:

Input and output capacitors:

Select capacitors with low equivalent series resistance (ESR) for both input (Cin) and output (Cout) positions to ensure voltage stability and minimize ripple. The input capacitor must withstand the RMS current; larger, higher-voltage capacitors often meet these requirements better. For stability and reduced ripple, the output capacitor should have both upper and lower ESR limits to prevent oscillation. At low temperatures, consider paralleling aluminum electrolytic and tantalum capacitors to maintain low ESR.

Inductor selection:

The choice of inductor impacts output ripple, efficiency, and thermal performance. EMI considerations favor closed magnetic structures (e.g., toroid cores) over open types. Continuous conduction mode is preferred for most designs and ensures smoother operation at higher loads; dedicated inductor value selection guides are available for all output voltage variants in the LM2575 family.

Catch diode:

Employ a fast-switching Schottky or soft recovery ultrafast diode as the freewheeling/catch diode. Placement close to the IC is essential to prevent EMI and switching noise. Standard slow rectifiers are not suitable.

PCB layout:

Minimize loop areas for high-frequency switching paths to reduce EMI and voltage spikes. Use single-point grounding or ground planes for best results. Keep feedback wiring short; place feedback programming resistors close to the regulator (for adjustable versions).

Thermal management:

Evaluate the thermal design depending on ambient conditions and board layout. In many cases, the TO-220-5 package can operate without additional heatsinking up to 50°C at full load, leveraging the PCB for thermal dissipation. For higher temperatures or higher input-output differentials, additional heatsinking may be necessary. Calculate the expected power dissipation using switching loss equations, and ensure device junction temperature remains below 110–125°C for reliability.

Thermal Management and Mechanical Factors for LM2575T-5G

The LM2575T-5G is primarily offered in a 5-lead TO-220 package, featuring an exposed heatsink tab for efficient thermal conduction. The TO-220 format allows direct mounting to PCB copper areas or to external heatsinks. Surface mount D²PAK versions are also available for automated assembly. Mechanical package outlines conform to JEDEC standards, ensuring compatibility with standard board layouts and heatsinking solutions.

Care should be taken in PCB design to maximize thermal conduction paths from the package, especially when using the D²PAK. For through-hole designs, the TO-220’s tab can be soldered directly to ground or a copper pad of sufficient size to aid in heat dissipation.

Alternative or Substitute Models for the LM2575T-5G

Although the LM2575T-5G is a robust and widely used solution, engineers may consider equivalent or replacement models under certain circumstances, such as product discontinuation or supply chain constraints. Suitable alternatives include:

Other voltage variants within the onsemi LM2575 family (such as LM2575T-3.3, LM2575T-12, LM2575T-15, or the adjustable LM2575T-ADJ)

The LM2595 series for higher efficiency requirements or additional features

Comparable fixed-frequency buck regulator ICs from major power IC manufacturers, ensuring input voltage and load current capabilities match the application requirements and that PCB and external component compatibility is verified

It is critical to perform a thorough cross-check of pinouts, regulator topology, and protection features before implementing an alternative device.

Conclusion

The LM2575T-5G from onsemi stands as a reliable, time-tested choice for power supply designers seeking compactness, high efficiency, and robust protection in a step-down regulator. Its wide input range, tolerant output regulation, and streamlined integration reduce both design time and component cost. For system engineers and procurement professionals, the LM2575T-5G offers a balanced architecture suitable for a broad spectrum of applications, with scalable family options and clearly defined design guidelines. If replacement is required, careful selection of functionally equivalent DC/DC converters—preferably from the LM2575 or LM2595 families—ensures smooth migration and secure long-term support in demanding environments.