Texas Instruments LM2575T-3.3/LF03

Overview

LM2575T-3.3/LF03 from Texas Instruments is a monolithic 1A step-down (buck) switching voltage regulator in TO-220 package, delivering a fixed 3.3V output with ±4% tolerance across 4.75–40V input and 0.2–1A load. It integrates PWM controller, power switch, and internal frequency compensation, enabling high-efficiency DC/DC conversion for embedded power rails without external feedback resistors.

For engineers reviewing the LM2575T-3.3/LF03 datasheet, LM2575T-3.3/LF03 pinout, LM2575T-3.3/LF03 application, or LM2575T-3.3/LF03 equivalent, this device serves as a drop-in replacement for linear regulators in space-constrained industrial and automotive subsystems where thermal management and board area are critical.

Technical Context

The LM2575T-3.3/LF03 implements a fixed-frequency (52 kHz) current-mode buck topology with cycle-by-cycle current limiting and thermal shutdown. Its internal NPN power switch exhibits 0.9V saturation voltage at 1A, enabling stable regulation under transient load steps up to 1A with minimal dropout.

It features TTL-compatible ON/OFF control (1.4V VIH min, 1.2V VIL max), 50 μA standby quiescent current, and operates over −40°C to +125°C junction temperature. Input voltage range is 4.75V to 40V, supporting wide-input industrial supplies and battery-backed systems.

Key Specifications

Pinout & Package

LM2575T-3.3/LF03 uses a 5-lead TO-220 package (Package Number NDH0005D) with integrated heat slug. Pin 3 is internally connected to the die substrate and must be electrically tied to ground for thermal and EMI performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2575T-3.3/KO3, the LF03 variant ensures regulatory compliance without performance trade-offs; versus MP1584EN-LF-Z, it trades higher-frequency miniaturization for inherent fault resilience and simpler BOM - making LM2575T-3.3/LF03 optimal for reliability-first industrial deployments.

Availability

LM2575T-3.3/LF03 is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control modules, medical diagnostics equipment, and telecom remote units requiring stable component supply across extended product lifecycles.

Supply support for LM2575T-3.3/LF03 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 and embedded processing technologies, with decades of expertise in power management ICs.

The LM2575 series was designed as a rugged, easy-to-use replacement for linear regulators in cost-sensitive, thermally constrained applications - emphasizing simplicity, reliability, and wide-input operation over feature density.

FAQ

What is the maximum input voltage rating for LM2575T-3.3/LF03?

The LM2575T-3.3/LF03 has an absolute maximum input voltage of 45V and a recommended operating maximum of 40V. Exceeding 40V risks violating the specified output voltage accuracy and efficiency performance, though brief transients up to 45V are tolerated per absolute ratings. For sustained operation above 40V, the LM2575HVT-3.3 variant (60V max) should be used instead of LM2575T-3.3/LF03.

Does LM2575T-3.3/LF03 require external feedback resistors?

No, LM2575T-3.3/LF03 does not require external feedback resistors. As a fixed-output variant, its 3.3V regulation is achieved via an internal resistor divider connected to the feedback (pin 4), which is not accessible externally. This eliminates tuning errors and improves long-term stability compared to adjustable versions like LM2575-ADJ, where resistor tolerance directly impacts output accuracy.

Can LM2575T-3.3/LF03 be used in synchronous rectification configurations?

No, LM2575T-3.3/LF03 cannot be used in synchronous rectification configurations. It integrates only a single NPN power switch and requires an external Schottky catch diode (e.g., SR103 or MBR340). The architecture lacks a second switch driver or complementary gate outputs needed for synchronous operation - unlike modern controllers such as TPS54302, which explicitly support external high-side/low-side MOSFET pairs.

What is the thermal shutdown threshold for LM2575T-3.3/LF03?

The LM2575T-3.3/LF03 activates thermal shutdown at approximately 150°C junction temperature, as specified in its Absolute Maximum Ratings. Once triggered, the device halts switching and enters a safe high-impedance state until junction temperature falls below ~135°C (typical hysteresis), after which normal operation resumes automatically. This protects against permanent damage during sustained overload or inadequate heatsinking conditions.

Is LM2575T-3.3/LF03 pin-compatible with LM2575T-5.0/LF03?

Yes, LM2575T-3.3/LF03 is pin-compatible with LM2575T-5.0/LF03 and all other fixed-output variants in the same TO-220 package (NDH0005D). Pin count, physical layout, terminal functions, and thermal pad connection are identical - only the internal feedback ratio differs. This allows board-level voltage scalability without layout changes, provided input/output capacitors and inductor are re-validated for the new output voltage.