Microchip Technology LM2576-5.0BT

Overview

LM2576-5.0BT from Micrel is a monolithic 3A step-down (buck) switching regulator with fixed 5.0V output, 52kHz internal oscillator, ±3% output voltage tolerance over line/load, 4V–40V input range, and thermal shutdown protection. It replaces linear regulators in industrial power supplies requiring high efficiency and minimal external components.

For engineers reviewing the LM2576-5.0BT datasheet, LM2576-5.0BT pinout, LM2576-5.0BT application, or LM2576-5.0BT equivalent, key selection factors include guaranteed 3A output current, TO-220-5 package thermal performance (θ_JA = 65°C/W), ON/OFF control with <200µA standby current, and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2576-5.0BT integrates a 52kHz fixed-frequency oscillator, error amplifier with 1.23V reference, PWM comparator, 3A NPN switch, and thermal shutdown circuitry. Its feedback loop is internally compensated, eliminating need for external compensation networks.

It operates in continuous conduction mode with cycle-by-cycle current limiting (5.8A typical peak limit) and features an ON/OFF pin that disables the output switch while drawing only 50µA typical standby current. The device maintains regulation down to 4V input and supports output loads up to 3A with ≤5.25V maximum output under full load and temperature extremes.

Key Specifications

Pinout & Package

LM2576-5.0BT uses the 5-lead TO-220-5 package with exposed tab (pin 3) for thermal dissipation. Mounting requires mechanical attachment to heatsink via tab; electrical isolation is required if tab is not connected to ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576-5.0WU, the LM2576-5.0BT offers identical regulation performance but requires through-hole assembly and delivers higher thermal resistance; compared with LM2596-5.0, it provides superior output accuracy, integrated enable control, and lower EMI due to its lower switching frequency - making it preferable for noise-sensitive industrial and medical applications.

Availability

LM2576-5.0BT is available at Aetrix Electronics and suitable for industrial power supplies, embedded system main rails, automotive aftermarket modules, and test equipment power stages requiring stable component supply, long lifecycle support, and RoHS-compliant sourcing.

Supply support for LM2576-5.0BT 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 semiconductor company specializing in analog, power management, and timing solutions before its acquisition by Microchip Technology in 2015. Its products emphasized high-reliability, ease-of-use, and robust thermal design.

The LM2576 series was designed as a drop-in replacement for three-terminal linear regulators in medium-power DC-DC conversion, targeting cost-sensitive industrial, telecom, and embedded applications where efficiency and thermal simplicity were critical.

FAQ

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

The LM2576-5.0BT has an absolute maximum input voltage rating of 45V, with recommended continuous operation up to 40V. Operation above 40V risks exceeding internal transistor breakdown limits and is not guaranteed across temperature or process variations. For 40V input applications, ensure sufficient derating margin and verify thermal performance under worst-case load conditions using the device's θ_JA = 65°C/W specification.

Does the LM2576-5.0BT require external feedback resistors to set the 5V output?

No, the LM2576-5.0BT does not require external feedback resistors. It is a fixed-output variant with internal resistor divider network calibrated to deliver 5.0V ±3%. Pin 4 (FEEDBACK) is internally connected and must remain unconnected in circuit - adding external resistors will disrupt regulation and may cause output instability or overvoltage.

Can the LM2576-5.0BT be used without a heatsink?

Yes, the LM2576-5.0BT can operate without an external heatsink at light-to-moderate loads (≤1.5A) and ambient temperatures ≤50°C, provided the TO-220 tab is mounted to ≥4 square inches of copper on the PCB. At full 3A load with 12V input, junction temperature rise exceeds 100°C without heatsinking - a minimum 10°C/W heatsink is recommended for continuous 3A operation at 25°C ambient.

What is the purpose of the ON/OFF pin (Pin 5) on the LM2576-5.0BT?

The ON/OFF pin (Pin 5) enables logic-level control of the LM2576-5.0BT output stage. Pulling this pin to ≥2.4V disables the internal switch, reducing quiescent current to <200µA. Pulling it to ≤1.0V enables normal regulation. This feature allows microcontroller-driven power sequencing, battery-saving sleep modes, or system-level fault shutdown - all without modifying the main power path.

Which diode is recommended for use with the LM2576-5.0BT in a standard buck configuration?

A Schottky diode rated for ≥3A average current and ≥60V PIV is recommended for the LM2576-5.0BT, such as the MBR360 (3A, 60V) or 11DQ06 (3A, 60V). These minimize forward voltage drop (typically 0.4–0.6V), reducing conduction losses and improving efficiency. Fast recovery diodes are not required due to the 52kHz switching frequency, but reverse recovery time should be <100ns to prevent switching spikes.