Texas Instruments LM2576T-12/LB03

Overview

LM2576T-12/LB03 from Texas Instruments is a monolithic 3-A non-synchronous step-down (buck) DC-DC switching regulator in TO-220-5 (KC) package, delivering fixed 12 V output with ±4% tolerance over line and load, 40 V max input voltage, and 52 kHz fixed-frequency operation. It serves as a high-efficiency replacement for linear regulators in industrial power supplies, motor drives, and test equipment where thermal management and minimal external components are critical.

For engineers reviewing the LM2576T-12/LB03 datasheet, LM2576T-12/LB03 pinout, LM2576T-12/LB03 application, or LM2576T-12/LB03 equivalent, key selection considerations include its 3-A continuous output capability, integrated cycle-by-cycle current limiting, TTL-compatible ON/OFF control with 50 μA standby current, and compatibility with standard off-the-shelf inductors-enabling compact, thermally robust buck converter designs without complex compensation.

Technical Context

The LM2576T-12/LB03 implements a fixed-frequency PWM architecture with an internal 52 kHz oscillator, error amplifier, bandgap reference (1.23 V), and NPN power switch. Its functional block includes undervoltage lockout behavior, thermal shutdown, and cycle-by-cycle peak current limiting to protect against overload and short-circuit conditions.

It operates in continuous conduction mode under full load but transitions to discontinuous mode at light loads-maintaining regulation without requiring external frequency synchronization or slope compensation. The feedback pin is internally connected to the 12 V output, eliminating external resistor dividers and simplifying layout while preserving ±4% output accuracy across −40°C to +125°C junction temperature.

Key Specifications

Pinout & Package

LM2576T-12/LB03 uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and integral heat slug electrically connected to GROUND. Thermal resistance R_θJA is 32.4°C/W on standard JEDEC 4-layer board, requiring heatsink mounting for sustained 3-A operation above ambient 50°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576T-12/LB03, LM2576T-12/LB02 offers identical performance with alternate traceability, while LM2576HVT-12 extends input range to 60 V at the cost of higher thermal resistance (R_θJA = 35.2°C/W) and reduced efficiency below 40 V-making LB03 optimal for standard 24–36 V industrial inputs.

Availability

LM2576T-12/LB03 is available at Aetrix Electronics and suitable for industrial motor drives, appliance control boards, test equipment power supplies, and merchant network infrastructure requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for LM2576T-12/LB03 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 designing analog ICs, embedded processors, and power management solutions for industrial, automotive, and communications markets-with over 50 years of power conversion innovation.

The LM2576 series was developed as part of TI's SIMPLE SWITCHER® portfolio to simplify high-current DC-DC design for engineers lacking deep SMPS expertise-emphasizing ease-of-use, fault resilience, and compatibility with standard passive components.

FAQ

What is the maximum input voltage rating for LM2576T-12/LB03?

The LM2576T-12/LB03 has an absolute maximum input voltage of 45 V and a recommended maximum operating input voltage of 40 V. Exceeding 40 V continuously risks thermal overstress and reduced lifetime; for 48-V nominal systems, the LM2576HVT-12 variant with 60-V rating is required. The device includes internal protection but is not rated for sustained operation above 40 V.

Does LM2576T-12/LB03 require external feedback resistors?

No, LM2576T-12/LB03 does not require external feedback resistors. As a fixed 12-V output version, the feedback pin (Pin 4) is internally connected to the output, eliminating the need for external resistor dividers. Connecting external components to Pin 4 will disrupt regulation and may cause overvoltage failure-TI's datasheet explicitly prohibits external feedback network attachment for fixed-output variants like LM2576T-12/LB03.

What thermal management is required for LM2576T-12/LB03 at full 3-A load?

At 3-A continuous load with 24-V input and 12-V output, LM2576T-12/LB03 dissipates approximately 4.2 W. With R_θJA = 32.4°C/W on a standard 4-layer board, junction temperature rises ~136°C above ambient-exceeding the 125°C max operating limit. Therefore, a heatsink mounted to the integral GROUND tab is mandatory; a 10°C/W heatsink reduces T_J to ~86°C at 25°C ambient, ensuring reliable operation.

Can LM2576T-12/LB03 be synchronized to an external clock?

No, LM2576T-12/LB03 cannot be synchronized to an external clock. It features a fixed internal 52-kHz oscillator with no sync input pin or frequency adjustment capability. Designs requiring clock synchronization-for EMI reduction or multi-rail phase interleaving-must use alternatives such as the LM76003 or LMR51430, which support external clock synchronization and higher switching frequencies.

What is the purpose of the ON/OFF pin on LM2576T-12/LB03?

Pin 5 (ON/OFF) provides TTL-compatible enable/disable control for LM2576T-12/LB03: ≤1.2 V enables regulation (active mode), while ≥2.2 V places the device in low-power shutdown with 50 μA typical standby current. This pin supports power sequencing, remote control, and energy-saving modes-directly drivable by microcontroller GPIO without level-shifting or pull-up resistors, as internal biasing ensures proper logic thresholds across temperature.