Texas Instruments LM2575T-3.3

Overview

LM2575T-3.3 from Texas Instruments is a monolithic 1A step-down (buck) switching voltage regulator in TO-220 package, delivering a fixed 3.3V output with ±4% tolerance across 4.75–40V input and 0.2–1A load. It integrates oscillator, PWM controller, and 65V DMOS power switch, enabling high-efficiency DC/DC conversion for embedded power rails without external pass transistors.

For engineers reviewing the LM2575T-3.3 datasheet, LM2575T-3.3 pinout, LM2575T-3.3 application, or LM2575T-3.3 equivalent, key selection considerations include its 52 kHz fixed-frequency operation, TTL-compatible shutdown (50 μA standby), thermal/current protection, and compatibility with standard off-the-shelf inductors - critical for industrial, automotive, and point-of-load designs requiring stable 3.3V at 1A.

Technical Context

The LM2575T-3.3 implements a current-mode PWM buck topology with internal 52 kHz oscillator and cycle-by-cycle current limiting. Its integrated 65V DMOS switch supports up to 1A continuous output with saturation voltage ≤1.4V at full load.

Regulation relies on internal 1.23V reference and feedback comparator; output voltage is factory-trimmed to 3.3V ±4% over temperature (−40°C to +125°C) and line/load conditions. Thermal shutdown activates at 150°C junction temperature, and the ON/OFF pin provides logic-level control with VIH ≥2.2V and VIL ≤0.8V.

Key Specifications

Pinout & Package

LM2575T-3.3 uses a 5-lead TO-220 package (Package Number NDH0005D) with exposed tab electrically connected to Pin 2 (Output). Mounting requires thermal interface to heatsink or PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LM2575HVT-3.3, the LM2575T-3.3 trades 20V input headroom for cost and thermal margin in 40V-max systems; versus MP1584EN-LF-Z, it delivers proven ruggedness and minimal external parts at the expense of switching frequency and current headroom.

Availability

LM2575T-3.3 is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical diagnostics requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for LM2575T-3.3 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.

The LM2575 series was designed as a drop-in replacement for linear regulators in medium-power DC/DC applications, targeting cost-sensitive, thermally constrained systems needing simple, robust 1A buck conversion.

FAQ

What is the maximum input voltage rating for the LM2575T-3.3?

The LM2575T-3.3 has an absolute maximum input voltage of 45V and is rated for continuous operation up to 40V. Exceeding 40V risks violating operating specifications, though brief transients within the 45V absolute max limit may be tolerated with proper clamping. Always maintain input within 4.75V–40V for guaranteed 3.3V regulation and thermal safety in the LM2575T-3.3.

Does the LM2575T-3.3 require external feedback resistors to set the output voltage?

No - the LM2575T-3.3 is a fixed-output variant with internal resistor divider trimmed to 3.3V. Pin 4 (Feedback) is internally connected to the output and not accessible externally. This eliminates component count, layout sensitivity, and drift concerns associated with external resistors, making the LM2575T-3.3 simpler to implement than adjustable versions like LM2575-ADJ.

Can the LM2575T-3.3 be used without a heatsink?

Yes - the LM2575T-3.3 can operate without an external heatsink at full 1A load when ambient temperature is ≤50°C and PCB copper area around the TO-220 tab exceeds ~4 in². Thermal resistance is 45°C/W junction-to-ambient under those conditions. For higher ambient or sustained loads, a heatsink or thermal pad is recommended to keep junction temperature below 125°C in the LM2575T-3.3.

What type of catch diode is recommended for use with the LM2575T-3.3?

A Schottky diode rated for ≥1.2× output current (≥1.2A) and ≥1.25× maximum input voltage (≥50V for 40V input) is recommended. TI specifies the SR103 or 1N5818 (30V, 1A) for 5V output; for LM2575T-3.3 at 40V input, a 40V/3A Schottky such as MBR340 is preferred. Fast recovery is unnecessary - Schottky's low forward voltage minimizes conduction loss and improves efficiency in the LM2575T-3.3.

How does the ON/OFF pin function in the LM2575T-3.3?

The ON/OFF pin (Pin 5) enables TTL-compatible shutdown: ≤0.8V forces the LM2575T-3.3 into active regulation; ≥2.2V disables switching and reduces quiescent current to 50 µA typical. The pin draws ≤30 µA in shutdown and ≤12 µA when enabled. No pull-up/down is required - direct connection to MCU GPIO suffices for controlled power sequencing in the LM2575T-3.3.