STMicroelectronics LDFMPT-TR

Overview

LDFMPT-TR from STMicroelectronics is a 500 mA very low dropout linear regulator in DFN6-3x3 package, designed for precision voltage regulation in space-constrained systems. It operates from 2.5 V to 16 V input, delivers fixed 3.3 V output with ±1% accuracy at 10 mA load, features logic-controlled enable (EN), open-drain Power Good (PG), and internal thermal/current protection - ideal for powering low-voltage microprocessors and memory in portable industrial equipment.

For engineers reviewing the LDFMPT-TR datasheet, LDFMPT-TR pinout, LDFMPT-TR application, or LDFMPT-TR equivalent, key selection criteria include dropout voltage ≤300 mV at 500 mA, quiescent current ≤200 µA under load, PG threshold at 0.92×VOUT, and thermal shutdown at 170 °C - all critical for battery-powered and thermally sensitive designs.

Technical Context

The LDFMPT-TR implements a high-gain error amplifier driving a PMOS pass transistor, enabling ultra-low dropout operation and fast transient response to line/load changes. Its adjustable reference architecture supports precise output regulation across temperature (±1.5% over −40 °C to +125 °C) and load (10 mA–500 mA).

It integrates dual-function pins: EN provides logic-level shutdown control (0.8 V low / 2 V high thresholds), while PG delivers open-drain fault signaling with hysteresis (0.8×VOUT falling edge). Internal protection includes current limiting (0.8 A short-circuit) and thermal shutdown (170 °C, 10 °C hysteresis).

Key Specifications

Pinout & Package

Package: DFN6-3x3 mm, exposed thermal pad (GND), RoHS-compliant ECOPACK2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM10533TR and LDL1133PU33R, LDFMPT-TR uniquely combines 500 mA drive, integrated PG/EN, and 300 mV dropout - making it the only choice for compact, sequenced, and thermally demanding embedded power rails.

Availability

LDFMPT-TR is available at Aetrix Electronics and suitable for industrial sensor nodes, medical wearables, embedded PC modules, and automotive body control units requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for LDFMPT-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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

LDFMPT-TR belongs to ST's LDFM family of very low-dropout linear regulators, engineered specifically for high-precision, low-noise, and thermally robust voltage regulation in space-constrained portable and industrial electronics.

FAQ

What is the minimum input voltage required for stable 3.3 V output at 500 mA?

The LDFMPT-TR requires VIN ≥ VOUT + VDROP = 3.3 V + 0.3 V = 3.6 V for full 500 mA output. At lower inputs (down to 2.5 V), output current is reduced per the dropout curve - e.g., at 3.0 V input, maximum load is ~200 mA. Absolute minimum VIN is 2.5 V per datasheet specification.

Can the ADJ pin be left floating on the LDFMPT-TR?

No. The ADJ pin is not connected internally on the fixed 3.3 V LDFMPT-TR variant and must remain unconnected - neither tied to GND nor pulled up. Floating it poses no risk, but intentional connection may cause undefined behavior or leakage paths. Always verify pin function against Table 1 in DS9220 Rev 7.

How is Power Good (PG) used in system sequencing?

PG is an open-drain output that pulls low when VOUT falls below 0.8×VOUT (2.64 V) and releases high when VOUT rises above 0.92×VOUT (3.036 V). Connect a 47 kΩ pull-up to 3.3 V; use the resulting logic signal to delay enablement of downstream ICs until regulated voltage is stable - critical for FPGA configuration and memory initialization.

Does LDFMPT-TR require external compensation components?

No. The LDFMPT-TR is internally compensated and stable with standard ceramic capacitors: ≥1 µF at VIN and ≥2.2 µF at VOUT. Stability is guaranteed across the specified ESR range (0.01–1 Ω for COUT = 2.2 µF), eliminating need for external RC networks or compensation resistors.