STMicroelectronics LF120CDT

Overview

LF120CDT from STMicroelectronics is a 12 V fixed-output, very low dropout (LDO) linear voltage regulator in TO-220FP package with logic-controlled shutdown, 500 mA output current capability, 0.45 V typical dropout at 200 mA, and ±2% output voltage accuracy at 25°C. It operates from −40 to 125°C and delivers low-noise regulation for battery-powered microcontroller subsystems requiring stable local power.

For engineers reviewing the LF120CDT datasheet, LF120CDT pinout, LF120CDT application, or LF120CDT equivalent, this page provides verified electrical specifications, thermal data, shutdown control behavior, stability requirements (2.2 µF ceramic output capacitor), and real-world use cases in portable instrumentation and automotive body electronics.

Technical Context

The LF120CDT implements a PNP pass transistor architecture enabling ultra-low dropout voltage (0.45 V typ. at 200 mA) and high PSRR (80 dB typ. at 120 Hz). Its internal current and thermal limiting protect against overload and junction overheating under sustained load.

It features TTL-compatible enable input (pin 2) with logic-low threshold ≤0.8 V and logic-high threshold ≥2.0 V, allowing precise system-level power sequencing. The device requires only a 2.2 µF output capacitor with ESR between 0.1–10 Ω for unconditional stability across temperature and load.

Key Specifications

Pinout & Package

LF120CDT is supplied in TO-220FP (Full Pack) package: 5-pin, vertical mounting, isolated tab, plastic body with heat sink pad. Pin 1 = Input, Pin 2 = Shutdown (TTL-compatible), Pin 3 = Ground, Pin 4 = Output, Pin 5 = Ground (thermal pad tie).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12 V LDO regulator applications.

Compared with LD1086DT12 and TLV1117-12CDT, LF120CDT uniquely balances ultra-low dropout, integrated shutdown, and TO-220FP thermal robustness-making it optimal for battery-sensitive, thermally demanding, and sequenced-power applications where 500 mA is sufficient.

Availability

LF120CDT is available at Aetrix Electronics and suitable for automotive body electronics, portable medical devices, industrial data loggers, and smart home gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF120CDT 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, designing and manufacturing analog, MCU, power, and sensing solutions for automotive, industrial, and consumer markets.

The LF00 series was developed specifically for ultra-low-dropout, low-quiescent-current regulation in battery-powered and thermally constrained systems-emphasizing simplicity, reliability, and minimal external components.

FAQ

What is the minimum input voltage required for stable 12 V output at 500 mA?

The LF120CDT requires VI ≥ VO + V_d = 12 V + 0.7 V = 12.7 V at 500 mA (max dropout per datasheet Table 9). Below that, output voltage sags proportionally. For guaranteed 12 V regulation across full load and temperature, design for ≥13.0 V minimum input.

Can the shutdown pin be left floating, or must it be actively driven?

The shutdown pin (pin 2) must never be left floating: its TTL-compatible input has no internal pull-up/down. Floating state risks undefined operation and potential ON/OFF oscillation. Tie to VI via 10 kΩ resistor for default ON, or drive actively with MCU GPIO for controlled sequencing.

Is the thermal pad (pin 5) electrically isolated or internally connected?

Pin 5 is the exposed thermal pad and is internally connected to ground (pin 3). It must be soldered to a dedicated PCB ground pour with ≥4 thermal vias to maximize heat transfer. Electrical isolation is not possible-this connection is mandatory for both thermal performance and functional grounding.

Does the 2.2 µF output capacitor requirement apply to all load conditions?

Yes-the 2.2 µF ceramic capacitor (ESR 0.1–10 Ω) is required for stability across the full operating range: −40 to 125°C, 0–500 mA load, and input voltages from 2.5 V to 16 V. Using smaller values or higher-ESR capacitors risks oscillation, especially at light loads and high temperatures.