STMicroelectronics LF18ABDT-TR

Overview

LF18ABDT-TR from STMicroelectronics is a 1.8 V, ±1% tolerance automotive-grade low-dropout linear regulator in PPAK-5 package, featuring 0.7 V dropout at 200 mA, 500 µA typical quiescent current in ON mode, and TTL-compatible inhibit control (pin 2). It delivers up to 500 mA output current with only 2.2 µF ceramic output capacitance and operates across –40 °C to 125 °C for engine control unit power rails.

For engineers reviewing the LF18ABDT-TR datasheet, LF18ABDT-TR pinout, LF18ABDT-TR application, or LF18ABDT-TR equivalent, this device is selected for battery-powered automotive subsystems requiring precise 1.8 V rail stabilization, low-noise operation, logic-controlled shutdown, and AEC-Q100 qualification.

Technical Context

The LF18ABDT-TR integrates an internal NPN pass transistor with thermal and current limiting, enabling stable regulation under transient load conditions while maintaining 82 dB supply voltage rejection at 120 Hz. Its inhibit function accepts TTL-level input (VIL ≤ 0.8 V, VIH ≥ 2 V) to disable output and reduce quiescent current to 50 µA.

Designed for automotive environments, it meets AEC-Q100 Grade 1 requirements with validated PAT, SYL, and SBL statistical testing. The PPAK-5 package provides low R_thJA of 100 °C/W and electrically connected tab to GND for thermal and EMI performance.

Key Specifications

Pinout & Package

LF18ABDT-TR uses the PPAK-5 surface-mount package (SMD, exposed thermal pad), with tab electrically connected to GND for enhanced thermal dissipation and EMI shielding. Package dimensions: 4.5 mm × 3.5 mm × 1.0 mm (max).

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST18T3G and TPS78018DRVR, LF18ABDT-TR uniquely combines AEC-Q100 Grade 1 qualification, TTL inhibit control, and PPAK thermal performance - making it the only choice for production automotive 1.8 V core regulation where reliability and functional safety are mandatory.

Availability

LF18ABDT-TR is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, infotainment I/O rails, and telematics modem power supplies requiring stable component supply, full automotive traceability, and lifecycle continuity.

Supply support for LF18ABDT-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 analog, MCU, power, and automotive ICs for industrial and transportation markets.

LFXX is ST's automotive-qualified LDO family targeting under-hood and body electronics, engineered to replace legacy regulators with lower dropout, tighter tolerance, and integrated inhibit functionality for modern E/E architectures.

FAQ

What is the maximum input voltage for LF18ABDT-TR, and what happens above that limit?

The absolute maximum input voltage is 40 V. When input exceeds 18 V, the device enters shutdown mode and disables output regulation. This behavior is specified in Table 1 (Note 1) of the datasheet and protects downstream circuitry during load-dump events without requiring external clamping.

Can LF18ABDT-TR be used without the inhibit pin connected?

Yes - if pin 2 (INH) is left unconnected or tied to VIN, the device remains permanently enabled. However, for automotive applications requiring sleep-mode current reduction, it must be actively driven low (≤0.8 V) to achieve 50 µA OFF-mode quiescent current.

Is the thermal pad (pin 5) required to be soldered to PCB ground?

Yes - the exposed thermal pad is electrically connected to GND and must be soldered to a minimum 100 mm² copper pour with ≥4 thermal vias (0.3 mm diameter) to meet R_thJA = 100 °C/W and prevent thermal shutdown under 500 mA continuous load.

Does LF18ABDT-TR require an input capacitor, and if so, what value?

A 0.1 µF ceramic input capacitor is recommended per Figure 3 test circuit and Section 4 electrical characteristics. It stabilizes input impedance and mitigates high-frequency noise from upstream converters or battery lines, though the device remains functional without it under low-noise conditions.