Microchip Technology LM2575-12BU

Overview

LM2575-12BU from Texas Instruments is a monolithic 1-A step-down voltage regulator IC with fixed 12 V output, 40 V input rating, 52 kHz switching frequency, and thermal shutdown protection. It operates in buck topology for DC-DC conversion in industrial power supplies and embedded system rails.

For engineers reviewing the LM2575-12BU datasheet, LM2575-12BU pinout, LM2575-12BU application, or LM2575-12BU equivalent, key selection criteria include output voltage tolerance (±4%), dropout behavior under load transients, thermal performance in TO-220 package, and compatibility with standard external diode/capacitor configurations.

Technical Context

The LM2575-12BU integrates an internal 1-A NPN switch, oscillator, error amplifier, and current-limit circuitry. Its 52 kHz fixed-frequency PWM control enables predictable EMI filtering and simplifies output capacitor selection using standard electrolytic types.

Designed for minimal external components, it requires only one external diode (e.g., 1N5822), one output capacitor (≥100 µF, low-ESR), and one input capacitor (≥100 µF). Feedback is internal - no resistor divider needed due to fixed 12 V output configuration.

Key Specifications

Pinout & Package

Package: TO-220-5 (straight lead, non-isolated tab). Tab is connected to GND for thermal conduction and EMI shielding.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2575H-12 and LM2596-12, the LM2575-12BU provides the best balance of ruggedness, simplicity, and thermal predictability in TO-220 for legacy-compatible 24 V input systems - especially where EMI filtering cost and long-term supply continuity matter more than footprint reduction.

Availability

LM2575-12BU is available at Aetrix Electronics and suitable for industrial control power supplies, embedded system rail generation, and test equipment auxiliary rails requiring stable component supply and long-lifecycle support.

Supply support for LM2575-12BU 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The LM2575 series was designed as a robust, easy-to-use buck regulator family targeting cost-sensitive, thermally demanding applications where reliability and minimal external components are essential.

FAQ

What is the maximum input voltage rating for the LM2575-12BU?

The LM2575-12BU has a maximum input voltage rating of 40 V DC. This rating is absolute maximum and includes all transients and ripple. Operation above this voltage risks permanent damage. For systems with higher nominal input (e.g., 48 V), the LM2575H-12 variant - rated to 63 V - is the appropriate alternative. The LM2575-12BU is optimized for 24 V industrial bus applications with adequate safety margin.

Does the LM2575-12BU require external feedback resistors?

No, the LM2575-12BU does not require external feedback resistors. It features an internally trimmed 12 V output, with the FB pin permanently connected to the internal reference. This eliminates resistor tolerance errors, layout sensitivity, and component count - distinguishing it from adjustable versions like LM2575-ADJ. All variants share the same TO-220-5 package and pinout, but only the fixed-output versions (e.g., LM2575-12BU) omit external feedback.

Can the LM2575-12BU be used in place of a 7812 linear regulator?

Yes, the LM2575-12BU can replace a 7812 in many applications, offering up to 75% efficiency versus ~40% for the 7812 at 500 mA from 24 V input. However, it introduces switching noise and requires an external diode and output capacitor. Layout must separate power and analog ground planes. The LM2575-12BU is ideal where thermal management is challenging, but a 7812 remains preferable for ultra-low-noise analog rails unless proper filtering is implemented.

What thermal considerations apply to the LM2575-12BU in TO-220 package?

The LM2575-12BU uses a TO-220-5 package with the metal tab electrically connected to GND. At 1 A load and 24 V input, typical power dissipation is ~12 W, requiring a minimum 10 cm² copper pour (2 oz) or small heatsink for operation above 50°C ambient. Thermal shutdown activates near 160°C junction temperature. Derating curves in the official datasheet specify safe operating area based on ambient temperature and airflow - critical for sealed enclosures.

Is the ON/OFF pin of the LM2575-12BU compatible with 3.3 V logic?

Yes, the ON/OFF pin of the LM2575-12BU is compatible with 3.3 V logic. It triggers enable at >2.5 V and disable at <1.3 V, with hysteresis to prevent chatter. A 3.3 V GPIO from an MCU or FPGA meets both thresholds reliably. When disabled, the LM2575-12BU draws only 50 µA quiescent current. No level-shifting is required, making it straightforward to integrate into modern low-voltage control architectures alongside the LM2575-12BU.