STMicroelectronics LD1086D2M33

Overview

LD1086D2M33 from STMicroelectronics is a fixed-output 3.3 V, 1.5 A low-dropout linear voltage regulator in D²PAK package, featuring ±1% output tolerance at 25 °C, 1.3 V typical dropout at full load, and internal thermal/overcurrent protection. It delivers stable power to microcontroller cores, FPGA I/O banks, and industrial sensor signal chains where input-to-output differential is constrained.

For engineers reviewing the LD1086D2M33 datasheet, LD1086D2M33 pinout, LD1086D2M33 application, or LD1086D2M33 equivalent, key selection criteria include dropout voltage under 1.5 A load, output accuracy across –40 °C to +125 °C, quiescent current behavior, stability with 10 µF output capacitance, and thermal resistance (R_thJC = 3 °C/W) for high-power-density PCB layouts.

Technical Context

The LD1086D2M33 uses a PNP-based pass transistor architecture with on-chip trimming for tight output regulation, enabling fixed 3.3 V output without external feedback resistors. Its adjust pin is internally connected to ground for fixed-voltage variants, eliminating external component dependency while retaining compatibility with adjustable LD1086B designs.

Thermal foldback and short-circuit current limiting are implemented via integrated sensing circuits that dynamically reduce output current above safe junction temperature (T_J = 150 °C) or when V_IN–V_OUT exceeds 25 V. Quiescent current flows into the load-not wasted as bias-improving efficiency over legacy PNP regulators.

Key Specifications

Pinout & Package

LD1086D2M33 is housed in a surface-mount D²PAK (SMD 2L STD-ST) package with exposed thermal pad. The tab is electrically connected to the OUTPUT pin, requiring appropriate PCB copper pour for thermal management and electrical isolation from ground planes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-33CDR and NCP1117DT33T5G, LD1086D2M33 provides tighter initial accuracy (±1% vs. ±2%), lower thermal resistance in D²PAK (3 °C/W vs. ≥50 °C/W), and load-referred quiescent current-making it optimal for high-current, thermally constrained, or precision analog applications.

Availability

LD1086D2M33 is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical instrumentation requiring stable component supply, long-term lifecycle assurance, and AEC-Q100-compliant alternatives.

Supply support for LD1086D2M33 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, specializing in power management, microcontrollers, and automotive-grade analog ICs.

The LD1086 series was designed for high-reliability industrial and automotive power regulation, emphasizing low dropout, tight output tolerance, and robust thermal protection in ruggedized packages like D²PAK and TO-220.

FAQ

What is the minimum input voltage required for LD1086D2M33 to maintain 3.3 V output at 1.5 A?

The minimum input voltage is 4.6 V, calculated as V_OUT + V_DROP(max) = 3.3 V + 1.5 V (guaranteed max dropout per datasheet Table 5). At typical 1.3 V dropout, 4.6 V input sustains regulation; however, design margin requires using 1.5 V worst-case for reliability across temperature and process variation.

Can LD1086D2M33 be used with ceramic output capacitors?

Yes-LD1086D2M33 is stable with ceramic capacitors ≥10 µF and ESR as low as 5 mΩ. Unlike older LDOs, it does not require minimum ESR for phase margin; this eliminates the need for series resistors or tantalum alternatives, reducing BOM count and footprint.

How does the thermal pad connection affect performance?

The D²PAK tab is electrically tied to the OUTPUT pin and serves as the primary thermal path. Soldering it to ≥2 cm² of inner-layer copper with ≥4 thermal vias (0.3 mm diameter) reduces junction-to-board thermal resistance by ~20 °C/W, enabling continuous 1.5 A operation at 60 °C ambient without forced airflow.

Is LD1086D2M33 pin-compatible with adjustable LD1086B variants?

No-LD1086D2M33 has GND on pin 3, while LD1086B has ADJ on pin 3. Though both share the same D²PAK footprint and IN/OUT pin positions, the third pin function differs. Interchange requires PCB modification; however, the fixed version simplifies layout by removing external resistor networks needed for adjustable variants.