STMicroelectronics LD1085D2M18R

Overview

LD1085D2M18R from STMicroelectronics is a fixed-output 1.8 V, 3 A low-dropout linear voltage regulator in D²PAK package, featuring ±1% output tolerance at 25 °C, 1.3 V typical dropout at full load, internal thermal and current limiting, and operation from –40 °C to +125 °C junction temperature - used for powering FPGA core rails, DSP I/O supplies, and industrial microcontroller subsystems.

For engineers reviewing the LD1085D2M18R datasheet, LD1085D2M18R pinout, LD1085D2M18R application, or LD1085D2M18R equivalent, this page delivers verified electrical specs, thermal performance data, package mechanical details, real-world use cases, and validated alternative parts with functional and application-level distinctions.

Technical Context

The LD1085D2M18R employs a PNP-based pass transistor architecture with on-chip trimming for tight output regulation, delivering 1.8 V with ±1% accuracy at 25 °C and ±2% across –40 °C to +125 °C. Its quiescent current flows into the load rather than being wasted as bias current, improving efficiency over legacy PNP regulators.

It requires only a 10 µF output capacitor for stability and supports input voltages up to 30 V DC. Dropout voltage remains ≤1.5 V at 3 A load, enabling operation with minimal headroom - e.g., 3.3 V input can sustain 1.8 V output at full rated current.

Key Specifications

Pinout & Package

D²PAK (TO-263) surface-mount package with exposed thermal pad for enhanced heat dissipation; compatible with standard reflow profiles and suitable for high-power density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-18CDCYR and TPS7A4701RGWR, the LD1085D2M18R uniquely balances high current (3 A), low dropout (1.3 V), and industrial temperature range in a thermally optimized D²PAK package - making it irreplaceable for power-dense digital subsystems where both current and thermal performance are non-negotiable.

Availability

LD1085D2M18R is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics equipment, and telecommunications infrastructure requiring stable component supply with long lifecycle visibility and consistent parametric performance.

Supply support for LD1085D2M18R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD1085 series belongs to ST's high-current linear regulator product line, engineered specifically for industrial and embedded applications demanding robust thermal behavior, tight output accuracy, and simplified fixed-voltage power delivery without external feedback networks.

FAQ

What is the minimum input voltage required for LD1085D2M18R to maintain regulation at 3 A?

The LD1085D2M18R requires a minimum input voltage of 3.3 V to maintain 1.8 V output at 3 A load, based on its maximum dropout voltage of 1.5 V. At lighter loads, dropout decreases - e.g., ~0.8 V at 1 A - allowing lower input voltages while retaining regulation.

Can LD1085D2M18R be used without an input capacitor?

No. A minimum 10 µF input capacitor is required for stability and transient response, as specified in the datasheet. Omitting it risks oscillation, poor line regulation, and potential damage during input voltage surges or hot-plug events.

Is the D²PAK package of LD1085D2M18R RoHS-compliant and lead-free?

Yes. The LD1085D2M18R in D²PAK packaging meets RoHS Directive 2011/65/EU and is manufactured with lead-free terminations and halogen-free molding compounds, per ST's ECOPACK®2 specifications documented in the official datasheet revision history.

Does LD1085D2M18R require a heatsink for continuous 3 A operation?

Yes - for continuous 3 A operation at ambient temperatures above 60 °C, a heatsink is required. With R_thJA = 62.5 °C/W (D²PAK), junction temperature rises ~188 °C above ambient at full load; a heatsink reducing R_thJA to ≤20 °C/W keeps T_J within the 125 °C limit at 85 °C ambient.