STMicroelectronics LF120ABPT-TR

Overview

LF120ABPT-TR from STMicroelectronics is a 12 V fixed-output, very low dropout (LDO) linear regulator in PENTAWATT-5 package with logic-controlled shutdown, delivering up to 500 mA output current, 0.45 V typical dropout at 200 mA, ±1% output voltage accuracy at 25°C, and 50 µA quiescent current in OFF mode. It serves as a local power supply for microcontroller cores, sensor interfaces, and battery-powered industrial modules requiring stable low-noise 12 V bias.

For engineers reviewing the LF120ABPT-TR datasheet, LF120ABPT-TR pinout, LF120ABPT-TR application, or LF120ABPT-TR equivalent, key selection criteria include dropout voltage at full load, shutdown logic compatibility (TTL), thermal resistance (R_thJC = 3°C/W), stability with 2.2 µF ceramic output capacitor, and operation across –40°C to 125°C junction temperature.

Technical Context

The LF120ABPT-TR implements a PNP pass transistor architecture enabling ultra-low dropout performance and inherent short-circuit/thermal protection. Its 5-pin PENTAWATT configuration integrates a dedicated TTL-compatible shutdown input (Pin 2) that forces the regulator into sub-100 µA quiescent state when pulled low.

Designed for high PSRR (80 dB typ. at 120 Hz) and low output noise (50 µV RMS, 10 Hz–100 kHz), it maintains regulation with only 2.2 µF output capacitance (ESR 0.1–10 Ω), eliminating need for large electrolytic capacitors in space-constrained embedded systems.

Key Specifications

Pinout & Package

PENTAWATT-5 (vertical mount, 5-pin) package with exposed tab for thermal dissipation; R_thJC = 3°C/W, R_thJA = 50°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117S12TR and TPS7A4701RGWR, the LF120ABPT-TR uniquely balances 500 mA capability, 0.45 V dropout, integrated shutdown, and PENTAWATT thermal performance - making it optimal for thermally constrained, battery-aware 12 V applications where pin count and simplicity matter.

Availability

LF120ABPT-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, portable test equipment, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF120ABPT-TR 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, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The LF00 series was developed specifically for low-power, low-dropout local regulation in battery-backed and thermally demanding embedded systems - emphasizing quiescent current efficiency, wide input range, and minimal external component count.

FAQ

What is the minimum input voltage required for regulation at 500 mA output?

The LF120ABPT-TR requires a minimum input voltage of 12.45 V to maintain 12 V output at 500 mA, based on its maximum dropout voltage of 0.45 V at 200 mA and conservative derating to 0.7 V at full load per datasheet Table 7. Input below this threshold causes output collapse or unregulated behavior.

Can the shutdown pin be left floating, or does it require a pull-up/down resistor?

The SHDN pin (Pin 2) must not be left floating: it has no internal pull-up or pull-down. A 10 kΩ pull-up to IN is recommended for default-ON operation; a direct MCU GPIO connection (with series 100 Ω resistor for ESD protection) is preferred for active control. Floating may cause erratic ON/OFF transitions due to noise susceptibility.

Is the 2.2 µF output capacitor mandatory, or can larger values improve transient response?

The 2.2 µF ceramic capacitor is the minimum value required for stability per the datasheet; larger values (e.g., 4.7–10 µF) are acceptable and improve load transient response, but do not reduce output noise or dropout. ESR must remain between 0.1 Ω and 10 Ω - polymer or MLCC types are suitable; aluminum electrolytics are not recommended due to high ESR drift.

How does thermal performance change if the exposed tab is not soldered to a copper plane?

Without soldering the TAB (Pin 5) to ≥4 cm² of 2 oz copper, R_thJA degrades from 50°C/W to >100°C/W, limiting continuous output current to <200 mA at 25°C ambient. Full 500 mA capability requires thermal vias under the tab and connection to inner-layer ground planes to achieve the specified R_thJC = 3°C/W path.