STMicroelectronics LD1085V50

Overview

LD1085V50 from STMicroelectronics is a fixed-output 5.0 V, 3 A low-dropout linear voltage regulator in TO-220 package, designed for high-current point-of-load regulation where input-to-output differential is constrained. It delivers ±1% output tolerance at 25 °C, 1.3 V typical dropout at full load, and operates across –40 °C to +125 °C junction temperature. Used in industrial power supplies, FPGA core logic rails, and embedded system auxiliary rails requiring stable 5 V at up to 3 A.

For engineers reviewing the LD1085V50 datasheet, LD1085V50 pinout, LD1085V50 application, or LD1085V50 equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and confirmed alternative parts with documented functional and thermal trade-offs.

Technical Context

The LD1085V50 integrates an internal bandgap reference (1.25 V), error amplifier, and NPN pass transistor - enabling low quiescent current (5–10 mA) that flows into the load rather than being wasted as bias current. Its dropout behavior is monotonic and guaranteed ≤1.5 V at 3 A across temperature, with thermal shutdown and current limiting active under fault conditions.

Unlike PNP-based regulators, it achieves higher efficiency at high load currents due to load-directed quiescent current flow and requires only a 10 µF output capacitor for stability. The device supports fixed 5.0 V output without external resistors and maintains ±2% regulation over full temperature and load range.

Key Specifications

Pinout & Package

LD1085V50 is supplied in TO-220 package (ECOPACK® compliant), featuring through-hole mounting, integrated heat slug on Pin 2, and standard 2.54 mm pin pitch. Thermal performance optimized for PCB copper pour and mechanical heatsinking via tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940CT-5.0 and TLV1117-50, LD1085V50 uniquely combines 3 A capability, 1.3 V dropout, and TO-220 thermal performance - making it the only single-device solution for industrial 5 V/3 A rails requiring minimal BOM count and proven reliability.

Availability

LD1085V50 is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and test equipment requiring stable component supply with long lifecycle visibility and traceable sourcing.

Supply support for LD1085V50 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 performance, tight output tolerance, and simplified system-level power architecture.

FAQ

What is the minimum input voltage required for LD1085V50 to regulate 5.0 V at 3 A?

The LD1085V50 requires a minimum input voltage of 6.3 V to maintain regulation at 3 A load, based on its guaranteed 1.5 V maximum dropout voltage. At lower input voltages, output collapses linearly - e.g., at 6.0 V input, output drops to ~4.5 V. Input must also remain ≥3.4 V for 1.8 V variants, but LD1085V50's specification starts at VI = 6.6 V per Table 6.

Can LD1085V50 be used in parallel to increase current capacity?

No - LD1085V50 is not designed for parallel operation. Its output voltage tolerance (±1%) and load regulation (≤10 mV) cause current imbalance between units, risking thermal runaway. ST recommends using a single LD1085V50 with adequate heatsinking or selecting a higher-current switching solution instead.

Does LD1085V50 require an input capacitor, and if so, what value?

Yes - ST specifies a minimum 10 µF aluminum or tantalum input capacitor placed within 10 mm of Pin 1 to suppress input ripple and prevent oscillation during fast load transients. Ceramic capacitors ≥4.7 µF may be used if ESR is ≥10 mΩ; lower-ESR ceramics require series resistance to ensure stability.

Is LD1085V50 qualified for automotive applications?

No - LD1085V50 is specified for industrial-grade operation (–40 °C to +125 °C) but is not AEC-Q100 qualified. ST offers automotive-grade variants (e.g., LD1085V50TR) with extended qualification, enhanced ESD protection, and PPAP documentation - these carry distinct order codes and packaging markings.