Microchip Technology LM2576-5.0BU TR

Overview

LM2576-5.0BU TR from Micrel is a fixed-output 5.0V, 3A step-down (buck) switching regulator in TO-263-5 package. It features 52kHz fixed-frequency operation, ±3% output voltage tolerance over line/load/temperature, internal thermal shutdown and cycle-by-cycle current limiting, and requires only four external components. It replaces linear regulators in industrial power supplies, embedded DC-DC conversion, and on-card regulation where efficiency and heat dissipation are critical.

For engineers reviewing the LM2576-5.0BU TR datasheet, LM2576-5.0BU TR pinout, LM2576-5.0BU TR application, or LM2576-5.0BU TR equivalent, key selection criteria include guaranteed 3A output current at 5V, 4V–40V input range, 82% typical efficiency at 12V_IN/3A/5V_OUT, ON/OFF control with <200µA standby current, and TO-263 thermal performance with θ_JA = 45°C/W (with 1 in² copper).

Technical Context

The LM2576-5.0BU TR integrates a 3A NPN switch, 52kHz oscillator, error amplifier with 1.23V reference, PWM comparator, and protection circuitry into a monolithic buck controller. Its fixed 5.0V output eliminates external feedback resistors, simplifying design versus adjustable variants.

It operates in continuous conduction mode with internal frequency compensation and uses standard off-the-shelf inductors (e.g., 330µH). Protection includes thermal shutdown triggered at T_J ≥ 150°C and peak current limit of 4.2–6.9A, ensuring robust fault handling without external sensing.

Key Specifications

Pinout & Package

LM2576-5.0BU TR uses the 5-lead TO-263 (D²PAK) surface-mount package with exposed thermal pad. The package measures 10.16mm × 13.97mm × 4.50mm and is RoHS-compliant with hot-melt solder exemption.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576-5.0WU, the LM2576-5.0BU TR offers identical performance but with hot-melt solder exemption for legacy manufacturing processes; versus LM2596-5.0, it trades higher frequency for proven 52kHz EMI behavior and integrated enable functionality - critical for system-level power management.

Availability

LM2576-5.0BU TR is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and embedded networking requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for LM2576-5.0BU 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 acquired by Microchip Technology in 2015. It specialized in power management, interface, and timing solutions for industrial and communications markets.

The LM2576 series was designed as a high-efficiency, easy-to-use buck regulator family targeting cost-sensitive, thermally constrained applications where simplicity and reliability outweigh ultra-high efficiency or miniaturization.

FAQ

What is the maximum input voltage rating for LM2576-5.0BU TR?

The absolute maximum input voltage for LM2576-5.0BU TR is 45V, but the recommended operating range is 4V to 40V. Operation above 40V risks exceeding safe junction temperature or violating SOA limits during transients. The device maintains regulation and protection functions across its full 4–40V range, making it suitable for 24V industrial and automotive applications with wide input variation.

Does LM2576-5.0BU TR require an external feedback resistor network?

No, LM2576-5.0BU TR does not require external feedback resistors. As a fixed-output variant, its 5.0V regulation is implemented internally using a precision-resistor divider tied to the 1.23V bandgap reference. Pin 4 (FEEDBACK) is internally connected and not accessible - eliminating resistor tolerance, temperature drift, and layout sensitivity associated with adjustable versions.

Can LM2576-5.0BU TR be used in a negative-output (inverting) configuration?

Yes, LM2576-5.0BU TR can be configured as a positive-to-negative inverting buck-boost converter per Micrel Application Note AN-12. In this topology, the IC regulates the magnitude of the negative output (e.g., –5V) using the same internal feedback structure, with modified external component placement. Output polarity reversal requires careful attention to grounding, diode orientation, and capacitor polarity.

What is the thermal performance of LM2576-5.0BU TR on a standard PCB?

LM2576-5.0BU TR has a junction-to-ambient thermal resistance (θ_JA) of 45°C/W when mounted on a PCB with approximately 1 in² of copper surrounding the leads and thermal pad. This allows ~2.2W of power dissipation before reaching the 150°C thermal shutdown threshold at 85°C ambient - sufficient for full 3A output at moderate input-output differentials (e.g., 12V→5V).

Is LM2576-5.0BU TR pin-compatible with LM2576-5.0BT?

No, LM2576-5.0BU TR is not pin-compatible with LM2576-5.0BT. The BU variant uses the 5-lead TO-263 (D²PAK) surface-mount package, while the BT variant uses the through-hole 5-lead TO-220 package. Although both share identical pin numbering (VIN, OUTPUT, GND, FEEDBACK, ON/OFF), their mechanical footprints, thermal paths, and mounting methods differ fundamentally - requiring separate PCB layouts.