STMicroelectronics LF120CDT-TR

Overview

LF120CDT-TR from STMicroelectronics is a 12 V fixed-output, very low-dropout linear voltage regulator in DPAK package with logic-controlled inhibit function, 0.45 V dropout at 500 mA, ±2% output accuracy at 25 °C, and automotive-grade qualification (AEC-Q100, -40 to 125 °C). It delivers up to 500 mA output current with only 2.2 µF output capacitance for stability and supports battery-powered infotainment subsystems requiring low-quiescent-current shutdown.

For engineers reviewing the LF120CDT-TR datasheet, LF120CDT-TR pinout, LF120CDT-TR application, or LF120CDT-TR equivalent, key selection criteria include dropout voltage under load, OFF-mode quiescent current (50 µA typ.), AEC-Q100 qualification status, thermal resistance (R_thJA = 100 °C/W), and compatibility with low-ESR ceramic output capacitors.

Technical Context

The LF120CDT-TR implements a PNP-based LDO architecture with internal current and thermal limiting, enabling robust operation in automotive ambient conditions. Its inhibit input (pin 2) accepts TTL-compatible logic levels (V_IL ≤ 0.8 V, V_IH ≥ 2 V) to enable/disable regulation without external circuitry.

It achieves 80 dB supply voltage rejection at 120 Hz and maintains stable regulation across -40 to 125 °C junction temperature, with output voltage tolerance tightened to ±2% over temperature and line/load variations per its "C" grade specification.

Key Specifications

Pinout & Package

DPAK (TO-252-3) package with exposed thermal pad electrically connected to GND; compact surface-mount footprint (6.6 × 6.2 mm) optimized for high-power density automotive PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST12T3G and TPS7B6750QPWPRQ1, the LF120CDT-TR uniquely combines 12 V fixed output, AEC-Q100 qualification, inhibit control, and sub-0.5 V dropout - making it the sole fit for automotive 12 V local regulation where all three attributes are mandatory.

Availability

LF120CDT-TR is available at Aetrix Electronics and suitable for automotive body electronics, infotainment power distribution, and ADAS camera modules requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for LF120CDT-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, and automotive-grade analog devices.

The LFXX series is ST's automotive-qualified LDO family targeting local regulation in harsh-environment vehicle ECUs, emphasizing low dropout, ultra-low quiescent current, and AEC-Q100 reliability.

FAQ

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

The LF120CDT-TR requires a minimum input voltage of 12.45 V to maintain 12 V output at 500 mA, based on its 0.45 V dropout specification. Below this, output voltage drops linearly with input; operation below 2.5 V input is not functional.

Can the inhibit pin be left floating in the application?

No - the inhibit pin must be actively driven. Floating causes undefined behavior due to internal leakage paths. Tie to GND for permanent ON or to V_IN (via resistor divider if >2 V) for controlled shutdown. A pull-down resistor (e.g., 100 kΩ to GND) ensures default ON state at power-up.

Is an input capacitor required for stable operation?

Yes - a minimum 0.1 µF ceramic capacitor (X7R, 10 V rating) is required at the input pin per the datasheet test conditions. It reduces high-frequency noise and improves transient response; placement within 5 mm of the IN pin is critical for optimal performance.

Does the DPAK thermal pad require solder paste stencil aperture optimization?

Yes - the exposed thermal pad must be fully soldered to a dedicated GND plane using a 70–80% solder paste coverage stencil aperture. Insufficient solder volume or voiding degrades R_thJA and risks thermal shutdown under sustained 500 mA load.