STMicroelectronics LF18CDT-TR

Overview

LF18CDT-TR from STMicroelectronics is a 1.8 V, ±2% tolerance, automotive-grade low-dropout linear regulator in PPAK-5 package with logic-controlled shutdown (TTL-compatible enable), 0.7 V dropout at 200 mA, 500 mA output current capability, and operation from −40 °C to 125 °C - used for local power regulation in engine control units and ADAS domain controllers.

For engineers reviewing the LF18CDT-TR datasheet, LF18CDT-TR pinout, LF18CDT-TR application, or LF18CDT-TR equivalent, this page delivers verified electrical specs, thermal data, automotive qualification status (AEC-Q100), stability requirements (2.2 µF ceramic), and real-world use context in safety-critical vehicle subsystems.

Technical Context

The LF18CDT-TR implements a PNP pass transistor architecture enabling ultra-low dropout (0.7 V typ. at 200 mA) and high PSRR (82 dB at 120 Hz). Its integrated inhibit function accepts TTL-level logic input on Pin 2, allowing precise system-level power sequencing and standby mode entry without external circuitry.

Thermal protection and current limiting are fully internal; no external components required beyond input/output capacitors. The device achieves stable regulation with only 2.2 µF output capacitance (ESR 0.1–10 Ω), reducing board area and cost versus legacy LDOs requiring ≥10 µF.

Key Specifications

Pinout & Package

LF18CDT-TR uses the PPAK-5 (Power Package) surface-mount package with exposed thermal pad (electrically connected to GND). Package dimensions: 4.5 mm × 3.5 mm × 1.0 mm (max height), thermal resistance R_thJC = 8 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST18T3G, LF18CDT-TR adds automotive qualification, shutdown control, and lower dropout; versus TPS78018DRVR, it trades ultra-low IQ for higher output current and proven PPAK thermal robustness in high-ambient under-hood locations.

Availability

LF18CDT-TR is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, body control modules, and infotainment head units requiring stable component supply across automotive production lifecycles.

Supply support for LF18CDT-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 silicon solutions for automotive, industrial, and power management markets.

LF18CDT-TR belongs to the LFXX family of automotive-grade LDOs engineered specifically for demanding under-hood and safety-critical vehicle subsystems requiring AEC-Q100 compliance and wide-temperature reliability.

FAQ

What is the maximum input voltage for LF18CDT-TR?

The absolute maximum DC input voltage is 40 V, but regulation is guaranteed only between 3.0 V and 16 V. Input voltages above 18 V force the device into shutdown mode per Table 1 of the datasheet - this is a built-in protection feature, not an operational range.

Does LF18CDT-TR require an input capacitor?

Yes - a minimum 0.1 µF ceramic capacitor must be placed as close as possible to the IN pin. This stabilizes the input impedance and prevents oscillation during transient load steps; omission risks instability or startup failure, especially with long PCB traces.

Can LF18CDT-TR be used without connecting the TAB pin?

No - the TAB (Pin 5) is electrically connected to GND and serves as the primary thermal conduction path. It must be soldered to a dedicated PCB copper pour tied to system ground; floating or unconnected TAB causes thermal runaway and premature failure above 200 mA load.

Is the 2.2 µF output capacitor value strict, or can higher values be used?

The 2.2 µF value is the minimum required for stability with ESR between 0.1 Ω and 10 Ω. Larger values (e.g., 4.7 µF or 10 µF) are acceptable and improve transient response, but must maintain ESR within that range - using low-ESR polymer or MLCCs outside this window may cause ringing or oscillation.