Texas Instruments LM2575T-ADJ/NOPB

Overview

LM2575T-ADJ/NOPB from Texas Instruments is a monolithic 1A step-down (buck) switching voltage regulator in TO-220 package, featuring adjustable output (1.23V–37V), 52 kHz fixed-frequency operation, and integrated thermal shutdown/current limiting. It replaces linear regulators in medium-power DC/DC conversion where efficiency and heat dissipation are critical-e.g., industrial power supplies with 8–40V input.

For engineers reviewing the LM2575T-ADJ/NOPB datasheet, LM2575T-ADJ/NOPB pinout, LM2575T-ADJ/NOPB application, or LM2575T-ADJ/NOPB equivalent, key selection criteria include output adjustability range, 1A continuous load capability, TO-220 thermal performance (θ_JA = 65°C/W), 4% output voltage tolerance, and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2575T-ADJ/NOPB implements a fixed-frequency PWM buck topology with internal 52 kHz oscillator, cycle-by-cycle current limiting, and thermal shutdown. Its feedback loop senses voltage at the FB pin referenced to 1.23 V ±4%, enabling precise output regulation via external resistor divider.

It operates across 8–40 V input, supports up to 1A output current, and delivers high efficiency (77% typical at 12V_IN/5V_OUT/1A). Standby current is 50 μA typical when TTL-shutdown is asserted via the ON/OFF pin.

Key Specifications

Pinout & Package

LM2575T-ADJ/NOPB uses a 5-lead TO-220 package (Package Number NDH0005D) with exposed tab electrically connected to Pin 2 (Output). Mounting requires isolation if output is not ground-referenced.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2576T-ADJ and MP1584EN-LF-Z, the LM2575T-ADJ/NOPB offers proven industrial reliability, simpler EMI management due to 52 kHz operation, and broader legacy design support-but trades off peak current headroom and miniaturization capability.

Availability

LM2575T-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, on-card DC/DC conversion, and positive-to-negative converter designs requiring stable component supply, long-lifecycle availability, and consistent parametric performance.

Supply support for LM2575T-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 experience in high-reliability power conversion ICs.

The LM2575 series belongs to TI's SIMPLE SWITCHER® portfolio, designed specifically for engineers seeking easy-to-use, robust, and cost-effective buck regulators that minimize external component count and simplify qualification in industrial and commercial applications.

FAQ

What is the minimum input voltage required for stable operation of the LM2575T-ADJ/NOPB?

The LM2575T-ADJ/NOPB requires a minimum input voltage of 8 V for stable regulation across its full output range. Below this, dropout occurs - e.g., to sustain 5 V output, VIN must exceed ~6.5 V plus diode drop and switch saturation, but datasheet guarantees start at 8 V. Operation below 8 V may result in unregulated output or oscillation.

How do I calculate the output voltage setting resistors for the LM2575T-ADJ/NOPB?

Use the formula V_OUT = 1.23 V × (1 + R2/R1), where R1 connects from FB (Pin 4) to GND and R2 connects from V_OUT (Pin 2) to FB. Select R1 between 1 kΩ and 5 kΩ (1% metal film recommended); then compute R2. For example, for 12 V output with R1 = 2.2 kΩ, R2 = 2.2 kΩ × ((12/1.23) − 1) ≈ 19.3 kΩ → use 19.1 kΩ (1%). The LM2575T-ADJ/NOPB relies on this divider for all output programming.

Does the LM2575T-ADJ/NOPB require a heatsink under 1A load conditions?

A heatsink is not required for the LM2575T-ADJ/NOPB at 1 A if ambient temperature stays ≤50°C and PCB copper area around the TO-220 tab exceeds ~4 in². With θ_JA = 65°C/W and typical 0.9 V saturation voltage, power dissipation is ~0.9 W - yielding ~58.5°C rise above ambient. At 25°C ambient, junction temperature reaches ~83.5°C, well below the 125°C max rating. Derate linearly above 50°C ambient.

Can the LM2575T-ADJ/NOPB be used in a buck-boost (inverting) configuration?

Yes - the LM2575T-ADJ/NOPB supports inverting buck-boost topology per TI Application Note SLVA053. In this mode, Pin 2 (Output) becomes the negative rail, Pin 1 (Input) supplies positive input, and the inductor/catch diode are reconfigured. Output voltage magnitude is adjustable from 1.23 V upward, with polarity inverted. The LM2575T-ADJ/NOPB's internal switch and protection remain fully functional in this arrangement.

What is the purpose of the ON/OFF pin (Pin 5) on the LM2575T-ADJ/NOPB?

Pin 5 provides TTL-compatible enable/disable control: applying ≥2.2 V enables regulation; ≤0.8 V disables the internal switch and reduces quiescent current to 50 μA typical. This pin supports system-level power sequencing and low-power sleep modes. It must be pulled to GND or driven actively - floating is undefined. The LM2575T-ADJ/NOPB enters low-power standby without affecting feedback or output capacitor discharge path.