STMicroelectronics LF25CDT

Overview

LF25CDT from STMicroelectronics is a 2.5 V fixed-output, low-dropout linear voltage regulator in TO-220FP package with logic-controlled shutdown, 500 mA output current capability, 0.35 V typical dropout at 500 mA, and ±2% output voltage accuracy over temperature. It serves as a local power supply for microcontroller cores, sensor interfaces, and battery-powered portable instrumentation requiring stable low-noise bias under variable load and input conditions.

For engineers reviewing the LF25CDT datasheet, LF25CDT pinout, LF25CDT application, or LF25CDT equivalent, key selection criteria include dropout voltage at full load, quiescent current in ON/OFF modes, thermal resistance (R_thJC = 5 °C/W), stability with 2.2 µF ceramic output capacitor, and TTL-compatible enable control for system-level power sequencing.

Technical Context

The LF25CDT implements a PNP pass transistor architecture enabling ultra-low dropout operation, with internal current limiting and thermal shutdown protection active across –40 °C to +125 °C junction temperature range. Its enable input (pin 2) accepts TTL-level logic signals to place the regulator in <0.1 mA quiescent standby mode without external circuitry.

Stability is achieved with only 2.2 µF output capacitance (ESR 0.1–10 Ω), eliminating need for large electrolytic capacitors. Supply voltage rejection exceeds 82 dB at 120 Hz and remains >65 dB up to 10 kHz, supporting noise-sensitive analog and mixed-signal loads.

Key Specifications

Pinout & Package

LF25CDT is housed in a 5-pin TO-220FP package with exposed tab (pin 3) for thermal conduction and mechanical mounting. Pin 2 is dedicated to TTL-compatible shutdown control; pins 1 and 5 are input and output respectively, while pin 4 is ground.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator applications.

Compared with LDL112M25R and LD3985M25R, the LF25CDT provides higher current capability, superior thermal performance via TO-220FP, and integrated shutdown control - making it optimal for industrial and automotive applications where reliability, heat dissipation, and system-level power management are prioritized over miniaturization.

Availability

LF25CDT is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC I/O modules, automotive body control units, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF25CDT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in power management, microcontrollers, sensors, and automotive ICs with broad manufacturing and quality infrastructure.

The LF00 series was designed specifically for low-noise, low-power, and battery-operated applications demanding high accuracy, wide input range, and robust thermal behavior in industrial and automotive environments.

FAQ

What is the minimum input voltage required for LF25CDT to maintain regulation at 500 mA?

The LF25CDT requires a minimum input voltage of 2.85 V to sustain 2.5 V output at 500 mA load, based on its 0.35 V typical dropout voltage specification. At higher ambient temperatures or with reduced heatsinking, the effective dropout may increase slightly; design margin should include worst-case 0.4 V dropout per datasheet limits.

Can LF25CDT operate without an input bypass capacitor?

No. A 0.1 µF ceramic capacitor is required between pin 1 (VI) and pin 4 (GND) to ensure stability and transient response. Omitting it risks oscillation under dynamic load changes and may cause output voltage overshoot or regulator latch-up during startup or step-load events.

Is the TO-220FP package lead-free and RoHS-compliant?

Yes. The LF25CDT TO-220FP package is manufactured per STMicroelectronics' standard RoHS-compliant process, with lead-free terminations and halogen-free molding compound. Full compliance documentation, including EU Declaration of Conformity and material content reports, is available through ST's official product page and Aetrix Electronics' technical support portal.

How does the enable pin behave during power-up when VI rises slowly?

The enable pin (pin 2) has no internal pull-up or pull-down; it must be actively driven to ≥2 V for ON or ≤0.8 V for OFF. During slow VI ramp-up, undefined logic state may occur unless external circuitry (e.g., RC delay or supervisor IC) ensures EN is held low until VI exceeds 2.5 V, preventing premature or erratic turn-on.