STMicroelectronics LD1084D2M33

Overview

LD1084D2M33 from STMicroelectronics is a fixed-output 3.3V, 5A low-dropout linear voltage regulator in D2PAK package, featuring 1.3V typical dropout at full load, ±1% output tolerance at 25°C, and internal thermal/power limiting for robust operation in industrial power rails and FPGA/ASIC core supply applications.

For engineers reviewing the LD1084D2M33 datasheet, LD1084D2M33 pinout, LD1084D2M33 application, or LD1084D2M33 equivalent, key selection considerations include dropout margin under 5A load, thermal resistance (R_thJC = 3°C/W), stability with ≥10µF output capacitance, and compatibility with legacy adjustable regulator footprints.

Technical Context

The LD1084D2M33 uses a PNP pass transistor architecture where quiescent current flows into the load-improving efficiency versus traditional NPN regulators. It integrates on-chip trimming for tight output accuracy and features internal current limiting, thermal shutdown, and safe-area protection.

Designed for fixed-voltage operation, it requires no external feedback resistors. Its 3.3V output is optimized for PCI bus termination, SCSI-2 active termination, and low-noise digital logic supplies, with RMS output noise of just 0.003% of V_O (10Hz–10kHz).

Key Specifications

Pinout & Package

Supplied in D2PAK (TO-263) thermally enhanced surface-mount package with exposed tab for PCB heat sinking. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940CT-3.3 and TLV1117-33, the LD1084D2M33 uniquely delivers 5A at 1.3V dropout in D2PAK, enabling compact high-current designs without derating or paralleling-critical for industrial and storage applications demanding both precision and power density.

Availability

LD1084D2M33 is available at Aetrix Electronics and suitable for industrial PLCs, FPGA power domains, SCSI-2 termination circuits, and PCI bus power rails requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LD1084D2M33 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, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The LD1084 series belongs to ST's high-current linear regulator product line, engineered specifically for applications needing robust, fixed-output regulation with minimal external components and superior thermal performance in TO-220 and D2PAK packages.

FAQ

What is the minimum input voltage required for stable 3.3V output at 5A?

The LD1084D2M33 requires a minimum input voltage of 4.6V (3.3V + 1.3V dropout) to maintain regulation at 5A load. At lighter loads, dropout decreases-e.g., ~0.8V at 2A-allowing operation from lower input rails while retaining margin for line sag and ripple.

Can LD1084D2M33 be used without an output capacitor?

No. A minimum 10µF output capacitor (tantalum or ceramic) is mandatory for stability and transient response. Omitting it risks oscillation, overshoot, or thermal runaway under dynamic load changes. The capacitor must be placed within 5mm of the OUT and GND pins.

How does the D2PAK package compare thermally to TO-220 for this device?

The D2PAK and TO-220 share identical R_thJC = 3°C/W, but D2PAK offers superior R_thJA (62.5°C/W vs. 50°C/W for TO-220) due to its surface-mount thermal pad. Effective PCB copper area under the exposed tab is essential to realize this advantage in real-world layouts.

Is LD1084D2M33 suitable for automotive applications?

While not AEC-Q100 qualified, the LD1084D2M33 operates from −40°C to +125°C and includes thermal shutdown-making it usable in non-safety-critical automotive subsystems (e.g., infotainment power rails) at the designer's risk. ST explicitly states non-automotive-grade parts should not be used in safety-critical roles.