Microchip Technology LM2575-3.3YWM-TR

Overview

LM2575-3.3YWM-TR from Micrel is a fixed-output 3.3V, 1A step-down (buck) switching regulator in a 24-pin wide SOIC package, featuring 52kHz fixed-frequency operation, ±3% output voltage tolerance over line and load, internal current limiting, thermal shutdown, and <200µA standby quiescent current. It replaces linear regulators in industrial power supplies requiring efficient 3.3V rail generation from 7–40V unregulated inputs.

For engineers reviewing the LM2575-3.3YWM-TR datasheet, LM2575-3.3YWM-TR pinout, LM2575-3.3YWM-TR application, or LM2575-3.3YWM-TR equivalent, key selection criteria include guaranteed 1A output current, TO-220-compatible pinout in SOIC-W24, 75% typical efficiency at 1A/12V_IN, and compatibility with standard off-the-shelf 330µH inductors and Schottky catch diodes.

Technical Context

The LM2575-3.3YWM-TR integrates a 52kHz oscillator, error amplifier, bandgap reference, and 1A NPN switch into a monolithic buck controller. Its feedback loop uses an internal 1.23V reference with direct connection to the FB pin for fixed-output variants-no external resistors required. The ON/OFF pin enables logic-level shutdown with <200µA standby current.

Thermal protection activates at 150°C junction temperature, and cycle-by-cycle current limiting clamps peak switch current to ≥1.7A. Input voltage range spans 4V to 40V, supporting wide-input industrial and automotive pre-regulation applications without external biasing circuitry.

Key Specifications

Pinout & Package

LM2575-3.3YWM-TR is housed in a 24-pin wide SOIC (WM) package with exposed thermal pad (pin 12 connected to GND). Pinout matches functional equivalence to TO-220 but distributed across 24 leads for improved thermal dissipation and routing flexibility on dense PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LM2575-3.3WU-TR, the LM2575-3.3YWM-TR trades thermal performance for compact SOIC-W24 packaging and simplified assembly; versus MP1584EN-LF-Z, it offers proven reliability, zero-compensation design, and direct replacement capability in existing 52kHz-based layouts - ideal for cost-sensitive, long-lifecycle industrial applications.

Availability

LM2575-3.3YWM-TR is available at Aetrix Electronics and suitable for industrial PLCs, embedded microcontroller power rails, automotive body control modules, test equipment power supplies, and edge-node IoT gateways requiring stable component supply across multi-year production cycles.

Supply support for LM2575-3.3YWM-TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Micrel Inc. was a U.S.-based analog and mixed-signal semiconductor company headquartered in San Jose, CA, acquired by Microchip Technology in 2015. Known for high-reliability power management and timing solutions.

The LM2575 series was designed as a rugged, easy-to-use buck regulator family targeting industrial, automotive, and telecom power conversion where simplicity, thermal robustness, and long-term availability were prioritized over ultra-high frequency or digital control.

FAQ

What is the maximum input voltage rating for LM2575-3.3YWM-TR?

The LM2575-3.3YWM-TR has an absolute maximum input voltage rating of 45V, with recommended continuous operation up to 40V. This allows safe use with 24V and 36V industrial bus inputs, including transient-tolerant designs that incorporate input TVS or LC filtering before the regulator. Exceeding 40V continuously risks exceeding thermal limits or violating SOIC-W24 package reliability specifications.

Does LM2575-3.3YWM-TR require external feedback resistors?

No, the LM2575-3.3YWM-TR is a fixed-output variant with internal resistor divider network set for 3.3V regulation. Unlike adjustable versions (e.g., LM2575-ADJ), it connects the FB pin internally to the 1.23V reference and output node - eliminating external resistors and associated drift or noise coupling. This simplifies layout and improves long-term output stability.

What is the thermal resistance (θ_JA) of LM2575-3.3YWM-TR in its SOIC-W24 package?

The LM2575-3.3YWM-TR has a junction-to-ambient thermal resistance (θ_JA) of 100°C/W when mounted on a standard PCB with approximately 1 square inch of copper surrounding the leads. This value assumes the exposed thermal pad (pin 12) is soldered to GND plane. Adding more copper or using thermal vias can reduce θ_JA significantly - critical for sustaining 1A output at ambient temperatures above 50°C.

Can LM2575-3.3YWM-TR be used in negative-output (inverting) configurations?

Yes, the LM2575-3.3YWM-TR can be configured as a negative-output buck-boost converter per Micrel Application Note AN-5. In this topology, the IC regulates –3.3V output using the same external components (inductor, diode, capacitors) as the standard buck circuit, with VIN referenced to the negative rail. Output polarity inversion is achieved by reorienting the inductor and diode - no modification to the LM2575-3.3YWM-TR itself is required.

What protection features are integrated into LM2575-3.3YWM-TR?

The LM2575-3.3YWM-TR integrates cycle-by-cycle current limiting, thermal shutdown at 150°C junction temperature, and internal soft-start functionality. These protections operate autonomously without external components: current limit prevents switch saturation during overload, thermal shutdown halts switching until safe temperature is restored, and soft-start controls output ramp rate to avoid inrush current stress on input capacitors and downstream loads.