STMicroelectronics LF50ACP

Overview

LF50ACP from STMicroelectronics is a very low-dropout linear voltage regulator delivering 5.0 V ±1.5% output at up to 500 mA, featuring 0.45 V dropout (at 200 mA), 500 µA typical quiescent current in ON mode, and TTL-compatible inhibit control (pin 2) in its 5-pin PPAK package. It serves as a local power supply for automotive microcontrollers, sensors, and infotainment subsystems requiring stable 5 V rail with standby capability.

For engineers reviewing the LF50ACP datasheet, LF50ACP pinout, LF50ACP application, or LF50ACP equivalent, key selection criteria include dropout voltage at 500 mA load, ±1.5% output accuracy over temperature, AEC-Q100 qualification, thermal performance in PPAK, and logic-controlled shutdown behavior under -40 °C to 125 °C operation.

Technical Context

The LF50ACP implements a PNP pass transistor architecture enabling ultra-low dropout (0.4 V typ. at 500 mA) and high PSRR (76 dB at 120 Hz). Its internal bandgap reference and error amplifier maintain output regulation across input voltages from 6 V to 16 V and load currents from 0 to 500 mA.

Shutdown is controlled via a dedicated TTL-compatible INH pin (pin 2), drawing only 50 µA in OFF mode. The device integrates thermal shutdown and current limiting, and achieves stability with just 2.2 µF output capacitance (ESR 0.1–10 Ω), eliminating need for large electrolytic capacitors.

Key Specifications

Pinout & Package

LF50ACP is housed in a thermally enhanced PPAK (Power Plastic Package) with exposed thermal pad, optimized for high-power-density automotive PCB layouts. The 5-pin configuration includes dedicated INH control and GND-connected tab for low-inductance thermal path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 5 V automotive LDO applications.

Compared with NCP1117ST50T3G, LF50ACP offers AEC-Q100 compliance and logic-controlled shutdown; versus TPS78050QDRVRQ1, it provides higher output accuracy tolerance band (±1.5% vs ±1%) but larger PPAK thermal footprint for higher sustained power dissipation.

Availability

LF50ACP is available at Aetrix Electronics and suitable for automotive ECU power rails, camera module biasing, body control modules, and infotainment subsystems requiring stable component supply with full AEC-Q100 traceability and extended temperature support.

Supply support for LF50ACP 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 analog, MCU, power, and automotive-grade ICs for industrial, automotive, and consumer markets.

The LFXX series is ST's automotive-qualified very-low-dropout regulator family targeting local power delivery in engine, chassis, and ADAS domains where low IQ, high PSRR, and AEC-Q100 reliability are mandatory.

FAQ

What is the minimum input voltage required for LF50ACP to regulate 5.0 V at 500 mA?

The minimum input voltage is 5.4 V, calculated as V_OUT + V_DROP = 5.0 V + 0.4 V (max dropout at 500 mA). Operation below this causes dropout - output drops linearly with input. Input must remain ≥6 V per absolute maximum rating to avoid damage during transient conditions.

Can LF50ACP be used without the INH pin connected?

Yes - leaving INH open or floating defaults the device to ON mode (500 µA IQ). However, for guaranteed OFF-state behavior, tie INH to GND through a 10 kΩ resistor. Do not leave INH unconnected in noisy automotive environments due to potential false triggering.

Is the exposed thermal pad on LF50ACP electrically isolated?

No - the PPAK thermal pad (pin 5/TAB) is internally connected to GND. It must be soldered to a GND plane with ≥4 thermal vias (0.3 mm diameter) to achieve specified R_thJA = 100 °C/W. Isolating the pad degrades thermal performance and risks thermal shutdown.

Does LF50ACP require an input capacitor?

Yes - a minimum 0.1 µF X7R ceramic capacitor placed within 5 mm of the IN pin is required for high-frequency stability and EMI suppression. Larger values (e.g., 1–10 µF) improve transient response but are not mandatory for basic regulation.