Texas Instruments LM2576T-ADJ/LF02

Overview

LM2576T-ADJ/LF02 from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC converter in TO-220-5 (KC) package, delivering adjustable output voltage from 1.23 V to 37 V with ±4% regulation over line and load, 52-kHz fixed-frequency operation, and TTL-compatible shutdown control. It replaces linear regulators in high-current industrial power supplies where thermal efficiency and minimal external component count are critical.

For engineers reviewing the LM2576T-ADJ/LF02 datasheet, LM2576T-ADJ/LF02 pinout, LM2576T-ADJ/LF02 application, or LM2576T-ADJ/LF02 equivalent, this page delivers verified pin functions, real-world thermal performance data (RθJA = 32.4°C/W), confirmed 3-A continuous output capability, oscillator frequency tolerance (±10%), and validated alternative options for buck regulator redesigns requiring input up to 40 V.

Technical Context

The LM2576T-ADJ/LF02 implements a fixed-frequency PWM controller with internal 52-kHz oscillator, cycle-by-cycle current limiting (ICL = 4.2–6.9 A), and thermal shutdown. Its error amplifier compares feedback voltage (1.23 V reference) against a resistor divider to regulate output, while the ON/OFF pin enables TTL-level shutdown with 50-μA standby current.

This device operates as a classic buck topology with integrated NPN switch, requiring only four external components: input capacitor, output capacitor, diode, and inductor. It supports discontinuous and continuous conduction modes, with saturation voltage (VSAT = 1.4–2.0 V at 3 A) and max duty cycle (93–98%) defining practical VIN–VOUT operating margins.

Key Specifications

Pinout & Package

LM2576T-ADJ/LF02 uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and thermally enhanced metal tab connected to GND. The tab must be mounted to a heatsink or large copper pour for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576HVT-ADJ, the LM2576T-ADJ/LF02 trades higher input voltage headroom for lower cost and identical thermal behavior in 40-V-limited systems; compared with LMR51430RNXR, it sacrifices efficiency and frequency flexibility for proven reliability, minimal BOM count, and straightforward PCB layout.

Availability

LM2576T-ADJ/LF02 is available at Aetrix Electronics and suitable for industrial motor drives, merchant server power supplies, test equipment, and home appliance control systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM2576T-ADJ/LF02 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 LM2576 series was designed as a drop-in replacement for three-terminal linear regulators in medium-power buck applications, emphasizing ease of use, thermal robustness, and minimal external component count for industrial and commercial power systems.

FAQ

What is the maximum input voltage rating for LM2576T-ADJ/LF02?

The absolute maximum input voltage for LM2576T-ADJ/LF02 is 45 V, with recommended operating range up to 40 V. Exceeding 40 V risks exceeding safe operating area limits and may trigger thermal shutdown or reduce lifetime. This differs from the HV variant (LM2576HVT-ADJ), rated for 60 V input. Always verify input transient margins in your system when using LM2576T-ADJ/LF02.

How do I set the output voltage for LM2576T-ADJ/LF02?

LM2576T-ADJ/LF02 uses a resistor divider between VOUT and GND, connected to the FEEDBACK pin (Pin 4), to set output voltage per the formula VOUT = 1.23 V × (1 + R1/R2). For example, R1 = 1.21 kΩ and R2 = 1.00 kΩ yields ~2.67 V. The internal 1.23-V reference has ±4% tolerance, so final output accuracy depends on both resistor tolerance and layout parasitics. LM2576T-ADJ/LF02 does not support digital programming - adjustment is purely analog.

Does LM2576T-ADJ/LF02 require a heatsink?

LM2576T-ADJ/LF02 uses a TO-220-5 (KC) package with RθJA = 32.4°C/W. Whether a heatsink is required depends on power dissipation: at 12 V_IN/5 V_OUT/3 A, dissipation is ~21 W, raising junction temperature by ~680°C above ambient - clearly requiring a heatsink. At lighter loads (<1 A) or lower VIN–VOUT differentials, board copper alone may suffice. Thermal design must account for ambient temperature and airflow; LM2576T-ADJ/LF02's metal tab must be soldered to GND and thermally coupled to copper or heatsink.

What is the purpose of the ON/OFF pin on LM2576T-ADJ/LF02?

The ON/OFF pin (Pin 5) provides TTL-compatible enable control: pulling it below 1.2 V activates regulation, while pulling it above 1.4 V places LM2576T-ADJ/LF02 into shutdown with 50-μA standby current. This allows precise power sequencing, remote on/off control, or energy-saving sleep modes. The pin must never float - tie to GND for always-on operation or use an open-collector driver. LM2576T-ADJ/LF02 does not support analog dimming or soft-start via this pin.

Can LM2576T-ADJ/LF02 be used in synchronous rectification configurations?

No, LM2576T-ADJ/LF02 is a non-synchronous buck converter with an internal NPN transistor and requires an external catch diode. It lacks a second gate driver or synchronous rectifier control signals. Attempting to replace the diode with a MOSFET without gate timing control will cause shoot-through or failure. For synchronous operation, consider TI's LMR51430 or LM76003 - LM2576T-ADJ/LF02 is optimized for simplicity and cost, not peak efficiency.