STMicroelectronics LDF18PT-TR

Overview

LDF18PT-TR from STMicroelectronics is a 1 A adjustable-output low-dropout linear regulator in DFN6 (3x3) package, operating from 2.6 V to 16 V input and delivering output voltages down to 0.8 V with ±1% precision at 25 °C. It features logic-controlled shutdown (EN pin), Power Good open-drain output (PG), 500 mV max dropout at 1 A, and operates across –40 °C to 125 °C junction temperature for use in microprocessor core supply and memory power rails.

For engineers reviewing the LDF18PT-TR datasheet, LDF18PT-TR pinout, LDF18PT-TR application, or LDF18PT-TR equivalent, key selection criteria include dropout voltage under full load, PG threshold accuracy relative to ADJ reference, EN logic thresholds, thermal shutdown hysteresis, and DFN6-3x3 layout compatibility with high-current PCB copper pours.

Technical Context

The LDF18PT-TR implements an internal N-channel pass transistor with error amplifier feedback referenced to a 0.8 V bandgap ADJ pin, enabling precise adjustable output via external resistor divider. Its control loop is optimized for fast transient response to load steps up to 1 A with 5 µs rise/fall time and stable operation with ≥2.2 µF ceramic output capacitance.

Thermal protection activates at 170 °C with 10 °C hysteresis; current limiting is internal and non-latching. The EN pin accepts logic-level inputs (0.8 V low / 2 V high), and PG provides open-drain status signaling with 0.92×V_ADJ rising-edge threshold and 0.8×V_ADJ falling-edge threshold.

Key Specifications

Pinout & Package

Package: DFN6 (3x3 mm, 0.9 mm height), exposed thermal pad connected to GND for enhanced heat dissipation (R_thJC = 6.5 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSP18P12T-TR and LDL112PU33R, the LDF18PT-TR uniquely supports adjustable output down to 0.8 V with full 1 A capability, PG monitoring, and industrial temperature range-making it the only option for scalable core voltage design with sequencing and fault reporting.

Availability

LDF18PT-TR is available at Aetrix Electronics and suitable for computer and laptop power delivery, battery-powered medical instrumentation, and industrial PLC I/O modules requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for LDF18PT-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 components for automotive, industrial, and consumer markets.

The LDF series was developed specifically for high-precision, low-noise, and thermally robust linear regulation in space-constrained embedded systems-targeting microprocessor core, memory, and sensor power rails where efficiency, accuracy, and reliability are critical.

FAQ

What is the minimum input voltage required for 1.0 V output at 1 A?

The LDF18PT-TR requires VIN ≥ VOUT + VDROP. With VOUT = 1.0 V and max VDROP = 500 mV at 1 A and 125 °C, minimum VIN is 1.5 V. However, per datasheet Section 4, dropout specification does not apply below 1.6 V output; for 1.0 V operation, VIN must be ≥2.6 V per absolute rating, and actual dropout is typically 200–300 mV under those conditions.

Can the PG pin drive a microcontroller GPIO directly?

Yes-the PG pin is open-drain with 0.4 V max low-level voltage at 6 mA sink current. A pull-up resistor (e.g., 10 kΩ to 3.3 V) allows direct interface to 3.3 V or 5 V GPIO. The rising edge triggers at 0.92×VADJ and falling edge at 0.8×VADJ, enabling reliable power-good detection without external comparators.

Is the exposed thermal pad electrically connected?

Yes-the exposed pad (EXP PAD) is internally connected to GND and must be soldered to a PCB thermal pad tied to system ground. This connection provides both electrical grounding and primary thermal path; omitting it degrades R_thJA by ~25 °C/W and risks thermal shutdown under 1 A load.

How does the LDF18PT-TR handle reverse polarity on VIN?

The device has no reverse-polarity protection. Absolute maximum rating specifies VIN ≥ –0.3 V; applying negative voltage-even briefly-can damage the internal pass transistor and bandgap reference. External reverse-voltage protection (e.g., series Schottky diode or ideal diode controller) is mandatory in battery-reversal-prone applications.