Texas Instruments LM2576T-3.3/NOPB

Overview

LM2576T-3.3/NOPB from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC converter in TO-220-5 (KC) package, delivering fixed 3.3-V output with ±4% regulation 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 embedded power rails, reducing thermal design burden in motor drives and industrial PSUs.

For engineers reviewing the LM2576T-3.3/NOPB datasheet, LM2576T-3.3/NOPB pinout, LM2576T-3.3/NOPB application, or LM2576T-3.3/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-3.3/NOPB integrates a 3-A NPN switch, fixed-frequency 52-kHz oscillator, error amplifier, bandgap reference (1.23 V), and thermal/current protection circuitry into a single TO-220-5 device. Its non-synchronous buck architecture uses an external catch diode and requires only four external components: input capacitor, output capacitor, inductor, and feedback network (shorted for fixed-output versions).

Operation relies on voltage-mode PWM control with internal compensation. The feedback pin is internally tied to the output for fixed 3.3-V variants, eliminating external resistor dividers. Shutdown is achieved via TTL-level logic on the ON/OFF pin (VIH ≥ 2.2 V, VIL ≤ 1.2 V), enabling precise sequencing and low-power standby modes.

Key Specifications

Pinout & Package

LM2576T-3.3/NOPB 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 LM2576T-3.3/NOPB, LM2576T-3.3 offers identical performance with non-RoHS packaging, while LM2596T-3.3 trades output current capacity for higher frequency and smaller magnetics - making LM2576T-3.3/NOPB the sole choice for validated 3-A fixed 3.3-V buck conversion in industrial environments.

Availability

LM2576T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, merchant server power supplies, and home appliance control boards requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for LM2576T-3.3/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 company headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and consumer markets.

The LM2576 series belongs to TI's SIMPLE SWITCHER® power converter family, engineered specifically for ease-of-use in cost-sensitive, thermally constrained DC-DC applications where reliability and minimal external component count are prioritized over ultra-high efficiency or MHz switching.

FAQ

What is the maximum input voltage rating for LM2576T-3.3/NOPB?

The absolute maximum input voltage for LM2576T-3.3/NOPB is 45 V, with recommended continuous operation up to 40 V. Exceeding 40 V risks exceeding thermal limits under full load, especially without adequate heatsinking. The HV variant (LM2576HV-3.3) supports up to 60 V input, but LM2576T-3.3/NOPB is strictly rated for 40 V max per TI's SNVS107G datasheet Section 6.1 and 6.3.

Does LM2576T-3.3/NOPB require an external feedback resistor divider?

No, LM2576T-3.3/NOPB does not require an external feedback resistor divider. As a fixed-output variant, its internal feedback node is factory-trimmed and internally connected to the OUTPUT pin. Pin 4 (FEEDBACK) is unused and must remain unconnected - unlike the adjustable LM2576ADJ version which requires external R1/R2.

What thermal resistance values apply to LM2576T-3.3/NOPB in TO-220 package?

For LM2576T-3.3/NOPB in KC (TO-220-5) package, the junction-to-ambient thermal resistance (RθJA) is 32.4°C/W on a standard JEDEC 4-layer board, and junction-to-case (bottom) RθJC(bot) is 0.4°C/W. These values assume proper soldering of the metal tab to a large copper plane or heatsink - inadequate thermal attachment can double effective RθJA.

Can LM2576T-3.3/NOPB be synchronized to an external clock?

No, LM2576T-3.3/NOPB cannot be synchronized to an external clock. It features a fixed internal 52-kHz oscillator with no synchronization pin or frequency adjustment capability. For synchronizable buck regulators, consider TI's newer LM5115 or TPS543x families - LM2576T-3.3/NOPB is designed for simplicity, not system-level timing coordination.

What is the purpose of the ON/OFF pin on LM2576T-3.3/NOPB?

Pin 5 (ON/OFF) on LM2576T-3.3/NOPB provides TTL-compatible enable/disable control: pulling it low (≤1.2 V) activates regulation, while pulling it high (≥2.2 V) places the device in standby mode with 50-μA typical quiescent current. This pin enables power sequencing, remote shutdown, and low-power sleep states without disabling upstream supplies.