Texas Instruments LM2576S-15/NOPB

Overview

LM2576S-15/NOPB from Texas Instruments is a monolithic 3-A non-synchronous step-down (buck) DC-DC regulator in TO-220-5 package, delivering fixed 15-V output with ±4% tolerance over line and load, 52-kHz fixed-frequency operation, and TTL-compatible ON/OFF control. It replaces linear regulators in medium-power industrial and embedded power supplies where thermal efficiency and minimal external components are critical.

For engineers reviewing the LM2576S-15/NOPB datasheet, LM2576S-15/NOPB pinout, LM2576S-15/NOPB application, or LM2576S-15/NOPB equivalent, key selection criteria include input voltage range (up to 40 V), 3-A continuous output capability, thermal performance in TO-220 package, and compatibility with standard off-the-shelf inductors and catch diodes.

Technical Context

The LM2576S-15/NOPB integrates a high-side NPN switch, fixed-frequency oscillator (47–58 kHz), error amplifier, current-limit comparator, and thermal shutdown circuit. Its feedback loop uses an internal 1.23-V reference and senses output directly at the feedback pin-shorted to VOUT for fixed versions-enabling stable regulation without external resistive dividers.

It operates in continuous conduction mode under full load and transitions to discontinuous mode at light loads. Protection features include cycle-by-cycle current limiting (4.2–6.9 A typical), thermal shutdown, and undervoltage lockout via the ON/OFF pin, which enters low-power standby (50 μA typical) when pulled above 1.4 V.

Key Specifications

Pinout & Package

LM2576S-15/NOPB uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and integral heat slug connected to GND. The tab is electrically tied to ground and serves as primary thermal path to heatsink or PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576T-15, LM2576S-15/NOPB provides RoHS-compliant packaging without performance trade-offs; compared with LM2596S-15, it delivers greater thermal margin and EMI predictability at the cost of larger passive components-making it preferable for industrial-grade reliability over miniaturization.

Availability

LM2576S-15/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, network equipment power subsystems, and home appliance control boards requiring stable component supply and long-term manufacturability.

Supply support for LM2576S-15/NOPB 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 highly reliable power conversion solutions.

The LM2576 series was designed as a rugged, easy-to-use SIMPLE SWITCHER® alternative to linear regulators-targeting cost-sensitive industrial, appliance, and test equipment applications where thermal efficiency and design simplicity are paramount.

FAQ

What is the maximum input voltage rating for LM2576S-15/NOPB?

The absolute maximum input voltage for LM2576S-15/NOPB is 45 V, but the recommended maximum operating voltage is 40 V per TI's datasheet specifications. Exceeding 40 V may reduce reliability or trigger internal protection circuits, especially at elevated temperatures. Always maintain at least 1-V margin below 45 V in production designs using LM2576S-15/NOPB.

Can LM2576S-15/NOPB be used without a heatsink?

LM2576S-15/NOPB can operate without an external heatsink at moderate loads and ambient temperatures-e.g., 3-A output at 25°C ambient with 12-V input yields ~2.4 W dissipation and junction temperature rise of ~78°C (using R_θJA = 32.4°C/W). However, for sustained 3-A operation above 40°C ambient or with input voltages >24 V, a heatsink or large copper pour is strongly recommended to keep T_J < 125°C.

How does the ON/OFF pin function on LM2576S-15/NOPB?

The ON/OFF pin on LM2576S-15/NOPB is a TTL-compatible enable input: pulling it below 1.2 V (typically to GND) activates regulation, while pulling it above 1.4 V (e.g., to 5 V) places LM2576S-15/NOPB in low-power shutdown with 50-μA typical standby current. The pin must never be left floating-it should be tied to GND through a 10-kΩ resistor if unused.

What type of diode is recommended for use with LM2576S-15/NOPB?

Texas Instruments recommends a Schottky diode such as the 1N5822 (3-A, 40-V) or SB560 for LM2576S-15/NOPB due to its low forward voltage (~0.5 V) and fast recovery-minimizing conduction losses and reverse-recovery ringing. For higher efficiency at light loads, a 3-A, 60-V Schottky like MBR360 is also suitable. Avoid standard PN diodes due to excessive power loss and thermal stress.

Is LM2576S-15/NOPB pin-compatible with other LM2576 fixed-output variants?

Yes, LM2576S-15/NOPB is fully pin-compatible with all other LM2576 fixed-output versions (e.g., LM2576S-5.0/NOPB, LM2576S-12/NOPB) in the same TO-220-5 package. They share identical pinout, thermal characteristics, and external component requirements-only the internal feedback network differs, so no PCB redesign is needed when changing output voltage within the LM2576S-xx family.