Texas Instruments LM2575N-ADJ/NOPB

Overview

LM2575N-ADJ/NOPB from Texas Instruments is a monolithic 1A step-down (buck) switching voltage regulator with adjustable output (1.23V to 37V), 52 kHz fixed-frequency internal oscillator, and integrated power switch. It delivers ±4% output voltage accuracy across line and load conditions, requires only four external components, and operates from 4.75V to 40V input - ideal for industrial DC-DC conversion where thermal efficiency and minimal BOM count are critical.

For engineers reviewing the LM2575N-ADJ/NOPB datasheet, LM2575N-ADJ/NOPB pinout, LM2575N-ADJ/NOPB application, or LM2575N-ADJ/NOPB equivalent, key selection considerations include its TO-220-5 package thermal performance (θ_JA = 65°C/W), cycle-by-cycle current limiting (1.7–3.0 A peak), TTL-compatible shutdown (50 μA standby), and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2575N-ADJ/NOPB implements a fixed-frequency PWM buck topology with internal 52 kHz oscillator and built-in N-channel MOSFET switch. Feedback is taken from the ADJ pin referencing an internal 1.23 V ±1.0% precision bandgap reference, enabling precise output programming via two external resistors (R1/R2).

It integrates thermal shutdown, current-limit protection, and low-power standby mode activated by the ON/OFF pin. The device operates in continuous conduction mode (CCM) under typical loads and reduces switching frequency to ~18 kHz during overload or short-circuit events to limit average power dissipation.

Key Specifications

Pinout & Package

LM2575N-ADJ/NOPB uses a 5-lead TO-220 package (package code NDH0005D) with exposed tab electrically connected to Pin 2 (Output). Mounting requires thermal interface 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 LM2575N-ADJ/NOPB, LM2576-ADJ offers higher current capability and slightly better efficiency at full load, while MP1584EN-LF-Z trades simplicity and ruggedness for miniaturization and higher switching frequency - requiring additional design validation.

Availability

LM2575N-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, embedded controllers, and on-card DC-DC converters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and production lots.

Supply support for LM2575N-ADJ/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 ICs.

The LM2575 series was designed as a simple, robust replacement for linear regulators in medium-power industrial and embedded applications - prioritizing ease of use, thermal resilience, and minimal external component count.

FAQ

What is the minimum input voltage required for stable operation of the LM2575N-ADJ/NOPB?

The LM2575N-ADJ/NOPB requires a minimum input voltage of 4.75 V to maintain regulation across all output voltages and load conditions. Below this threshold, the internal circuitry cannot sustain proper switching operation or feedback control, resulting in dropout or unregulated output. This value is specified in the Electrical Characteristics table under "Operating Ratings" for LM2575-N devices.

Can the LM2575N-ADJ/NOPB be used in a negative-output (inverting) configuration?

Yes, the LM2575N-ADJ/NOPB can be configured as a positive-to-negative buck-boost converter by connecting the input to ground and the output to the negative rail, with the inductor and diode rearranged per TI Application Note SLVA019. This topology leverages the same internal switch and control architecture, but requires careful attention to grounding, feedback reference, and output capacitor polarity.

What is the purpose of the ON/OFF pin (Pin 5) on the LM2575N-ADJ/NOPB, and how is it driven?

The ON/OFF pin (Pin 5) provides TTL-compatible enable/disable control: applying <0.8 V (logic low) places LM2575N-ADJ/NOPB into standby mode with 50 μA quiescent current, while >2.2 V (logic high) enables normal regulation. It draws ≤30 μA and may be driven directly from microcontroller GPIO or open-collector logic without buffering.

How does the feedback reference voltage of the LM2575N-ADJ/NOPB affect output accuracy?

The LM2575N-ADJ/NOPB uses a precision 1.23 V ±1.0% internal reference at the ADJ pin. Output voltage accuracy depends on both this reference tolerance and the resistor divider (R1/R2) tolerance. For example, using 1% metal-film resistors with the 1.23 V reference yields typical output accuracy within ±2.5% over temperature and line/load - sufficient for most non-precision industrial applications.

Is a heatsink required for the LM2575N-ADJ/NOPB when delivering 1 A at 12 V input and 5 V output?

At 12 V_IN/5 V_OUT/1 A, LM2575N-ADJ/NOPB dissipates approximately 1.8 W (P_D ≈ (12−5)×1 − 5×0.77 = 7 − 3.85 = 3.15 W × efficiency loss). With θ_JA = 65°C/W and 25°C ambient, junction temperature rises ~120°C - exceeding the 125°C max operating limit. A modest heatsink (θ_SA ≤ 20°C/W) or ≥4 in² copper pour is required to maintain safe operation.