Texas Instruments LM2576T-5.0/NOPB

Overview

LM2576T-5.0/NOPB from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC switching regulator in TO-220-5 (KC) package, delivering fixed 5.0 V output with ±4% tolerance over line and load, 40 V max input voltage, and 52 kHz fixed-frequency operation. It replaces linear regulators in medium-power embedded power supplies where thermal management and efficiency are critical.

For engineers reviewing the LM2576T-5.0/NOPB datasheet, LM2576T-5.0/NOPB pinout, LM2576T-5.0/NOPB application, or LM2576T-5.0/NOPB equivalent, key selection considerations include its 3-A continuous output capability, TTL-compatible ON/OFF control with 50 µA standby current, cycle-by-cycle current limiting, thermal shutdown protection, and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2576T-5.0/NOPB integrates a high-side NPN switch, fixed-frequency oscillator, error amplifier, and thermal/current protection circuitry into a single TO-220-5 device. Its architecture uses external diode-based synchronous rectification and requires only four external components: input capacitor, output capacitor, inductor, and feedback network (shorted for fixed-output versions).

It operates in continuous conduction mode under full load and transitions to discontinuous mode at light loads, maintaining regulation across −40°C to +125°C junction temperature. The internal 1.23 V reference and comparator enable precise output regulation without external resistive dividers for fixed-voltage variants.

Key Specifications

Pinout & Package

LM2576T-5.0/NOPB uses the KC (TO-220-5) package with 10.16 mm × 8.51 mm body size and integrated heat slug connected to GROUND. Thermal resistance is R_θJA = 32.4°C/W on standard PCB, requiring minimal heatsinking up to ~2 W dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576HVT-5.0/NOPB, the LM2576T-5.0/NOPB trades 20 V input headroom for lower cost and identical thermal performance at ≤40 V inputs; versus LMR51430RNXR, it offers simpler implementation and proven reliability at the expense of efficiency and integration level.

Availability

LM2576T-5.0/NOPB is available at Aetrix Electronics and suitable for industrial motor control, embedded PLCs, test equipment auxiliary supplies, and appliance control boards requiring stable component supply and long-term manufacturability.

Supply support for LM2576T-5.0/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 power conversion ICs.

The LM2576 series was designed as a rugged, easy-to-use replacement for linear regulators in medium-power DC-DC applications where simplicity, thermal resilience, and fault protection are prioritized over ultra-high efficiency.

FAQ

What is the maximum input voltage rating for LM2576T-5.0/NOPB?

The absolute maximum input voltage for LM2576T-5.0/NOPB is 45 V, but the recommended operating maximum is 40 V per TI's datasheet. Exceeding 40 V risks premature failure due to internal transistor stress, especially at elevated temperatures. For 48 V or higher input systems, the LM2576HVT-5.0/NOPB (60 V rated) is the appropriate alternative. Always observe derating curves in Section 6.3 of the LM2576T-5.0/NOPB datasheet.

Does LM2576T-5.0/NOPB require an external feedback resistor divider?

No, LM2576T-5.0/NOPB does not require an external feedback resistor divider. As a fixed-output 5.0 V variant, its internal feedback network is factory-trimmed and connected internally; Pin 4 (FEEDBACK) is unused and left unconnected in standard operation. External resistors are only needed for the adjustable version (LM2576ADJ). Incorrect connection of resistors to Pin 4 on LM2576T-5.0/NOPB will disrupt regulation.

How much heat sinking is needed for LM2576T-5.0/NOPB at 3 A output?

At 3 A output with 12 V input and 5 V output, LM2576T-5.0/NOPB dissipates approximately 1.8 W (P_D ≈ (V_IN−V_OUT)×I_OUT + V_OUT×I_OUT×(1/η−1)). With R_θJA = 32.4°C/W in TO-220-5, junction rise is ~58°C above ambient - acceptable up to +67°C ambient for 150°C max T_J. A small 15 cm² copper pour on the PCB is sufficient; forced air or metal heatsink is unnecessary unless ambient exceeds 70°C.

Can LM2576T-5.0/NOPB be synchronized to an external clock?

No, LM2576T-5.0/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 52 kHz oscillator with no sync input pin or frequency adjustment capability. For applications requiring synchronization (e.g., multi-rail systems avoiding beat frequencies), consider alternatives like the LM5115 or newer synchronous buck controllers with SYNC pins. The LM2576T-5.0/NOPB is optimized for simplicity, not system-level timing coordination.

What is the purpose of the ON/OFF pin on LM2576T-5.0/NOPB?

The ON/OFF pin (Pin 5) on LM2576T-5.0/NOPB enables TTL-compatible shutdown control: pulling it ≥1.4 V disables switching and reduces quiescent current to 50 µA typical, while ≤1.2 V enables normal operation. It is not a soft-start pin - output ramps at full slew rate upon enable. This pin supports power sequencing, battery-saving modes, and system-level fault isolation. Leaving it floating is prohibited and may cause erratic behavior.