onsemi LM2574N-012

Overview

LM2574N-012 from Texas Instruments is a monolithic 0.5-A non-synchronous step-down (buck) DC-DC regulator in PDIP-8 package, delivering fixed 12 V output with ±4% tolerance over line and load, 40 V max input voltage, and 52 kHz fixed-frequency operation. It serves as an efficient replacement for linear regulators in industrial power supplies, embedded controllers, and distributed power architectures.

For engineers reviewing the LM2574N-012 datasheet, pinout, applications, or equivalent options, key selection considerations include its 12 V fixed output, thermal shutdown and cycle-by-cycle current limiting, 50 μA standby current in TTL shutdown mode, and compatibility with standard off-the-shelf inductors - all critical for reliable low-component-count buck converter design.

Technical Context

The LM2574N-012 integrates a 0.5-A NPN switch, 1.23 V precision bandgap reference, error amplifier, PWM comparator, 52-kHz oscillator, and thermal/current protection circuitry into a single PDIP-8 IC. Its non-synchronous architecture requires only four external components: input capacitor, output capacitor, diode, and inductor.

Operation relies on feedback via the FB pin shorted to OUTPUT for fixed-output versions, enabling regulation without external resistors. The ON/OFF pin provides TTL-compatible enable control (low = active), while PWR_GND and SIG_GND pins are separately routed to minimize noise coupling between power and signal paths.

Key Specifications

Pinout & Package

LM2574N-012 uses the 8-pin PDIP (Plastic Dual In-line Package) with body size 6.35 mm × 9.81 mm. Thermal resistance R_θJA is 60.4°C/W, requiring minimal copper area for passive heatsinking in most 0.5-A applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2574HVN-12, the LM2574N-012 trades input voltage headroom for cost and thermal simplicity; compared with LM2596-12, it prioritizes design familiarity and component reuse over peak efficiency or current capability - making it ideal for maintenance, replacement, and cost-sensitive industrial applications.

Availability

LM2574N-012 is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, and point-of-load converters requiring stable component supply, long-term lifecycle support, and proven reliability in harsh environments.

Supply support for LM2574N-012 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, specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in power conversion ICs.

The LM2574x SIMPLE SWITCHER® series was designed specifically for engineers seeking easy-to-use, low-component-count DC-DC solutions that replace linear regulators in industrial, automotive, and consumer power systems - emphasizing robustness, thermal resilience, and design simplicity.

FAQ

What is the maximum input voltage rating for the LM2574N-012?

The LM2574N-012 has a maximum input voltage rating of 40 V, as specified in the Absolute Maximum Ratings table. This rating applies across the full operating temperature range and defines the upper limit beyond which permanent device damage may occur. Operation above this voltage - even briefly - risks irreversible failure of the internal NPN switch and protection circuitry. Always include input transient suppression if used in environments with potential voltage spikes.

Does the LM2574N-012 require external feedback resistors to set its output voltage?

No, the LM2574N-012 does not require external feedback resistors. As a fixed-output variant, it internally connects the FB pin to the OUTPUT pin, establishing a precise 12 V regulation point using the internal 1.23 V reference and integrated resistor network. This eliminates component count, layout sensitivity, and resistor tolerance errors - a key advantage over adjustable versions like the LM2574N-ADJ.

How does the ON/OFF pin function on the LM2574N-012?

The ON/OFF pin on the LM2574N-012 provides TTL-compatible enable control: a logic-low voltage (≤1.2 V) activates regulation, while a logic-high voltage (≥2.2 V) places the device in low-power shutdown mode with 50 μA typical standby current. The pin must never be left floating - a 10 kΩ pull-down resistor to GND ensures default-on behavior and prevents erratic startup or oscillation.

What thermal considerations apply to the LM2574N-012 in continuous operation?

The LM2574N-012 has a junction-to-ambient thermal resistance (R_θJA) of 60.4°C/W in the PDIP-8 package. At 0.5 A output and 12 V, typical power dissipation is ~1.2 W - resulting in ~72°C junction rise above ambient. To maintain safe operation below the 150°C maximum junction temperature, ambient must stay below ~78°C with standard PCB copper; adding thermal relief pads or airflow improves margin. Thermal shutdown activates if this limit is exceeded.

Can the LM2574N-012 be used in a positive-to-negative (buck-boost) configuration?

Yes, the LM2574N-012 can be configured as a positive-to-negative converter per TI's Application Note SNVA227. In this topology, the OUTPUT pin drives the inductor, the diode is reversed, and the output capacitor references ground to generate a negative rail. Output magnitude remains regulated at 12 V (i.e., –12 V), but efficiency and transient response differ from buck mode. Layout must strictly follow recommended grounding and loop-area minimization guidelines to avoid instability.