STMicroelectronics LD1085V36

Overview

LD1085V36 from STMicroelectronics is a fixed-output 3.3 V, 3 A low-dropout linear voltage regulator in TO-220 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. It delivers stable power to microcontroller cores, FPGA I/O banks, and industrial sensor signal chains where input-to-output headroom is constrained.

For engineers reviewing the LD1085V36 datasheet, LD1085V36 pinout, LD1085V36 application, or LD1085V36 equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and confirmed alternative options with functional trade-offs.

Technical Context

The LD1085V36 uses an NPN-based pass transistor architecture, enabling quiescent current to flow into the load rather than being wasted-improving efficiency over legacy PNP regulators. Its reference voltage is trimmed on-chip to 1.25 V ±1%, directly enabling tight output accuracy without external resistors.

It requires only a 10 µF output capacitor for stability and supports adjustable configurations via the ADJ pin (though LD1085V36 is fixed 3.3 V). Dropout voltage remains ≤1.5 V across –40 °C to +125 °C and full 3 A load, with thermal regulation of 0.008–0.04 %/W ensuring minimal output drift during transient heating.

Key Specifications

Pinout & Package

LD1085V36 is supplied in TO-220 package (ECOPACK® compliant), with exposed tab electrically connected to the output pin for thermal conduction and mechanical mounting.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2936MP-3.3/NOPB, LD1085V36 delivers 60× higher output current and tighter tolerance but consumes more quiescent power; versus TLV1117-33CDCYR, it adds ±1% accuracy, guaranteed thermal foldback, and superior PSRR-justifying use in industrial control and automotive body electronics.

Availability

LD1085V36 is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical sensor subsystems requiring stable component supply with long-term manufacturability and traceable sourcing.

Supply support for LD1085V36 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 power management applications.

LD1085V36 belongs to ST's high-current LDO family, engineered specifically for industrial and automotive point-of-load regulation where reliability, thermal resilience, and tight DC accuracy are mandatory-not just general-purpose voltage regulation.

FAQ

What is the minimum input voltage required for LD1085V36 to maintain regulation at 3 A?

The LD1085V36 requires a minimum input voltage of 4.6 V to sustain 3.3 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 operation down to 4.1 V input. Input below 4.6 V at full load causes output collapse.

Can LD1085V36 be used in adjustable mode despite its fixed 3.3 V designation?

No-LD1085V36 is factory-trimmed for fixed 3.3 V output and lacks an ADJ pin; only the adjustable variants (e.g., LD1085V, LD1085D2T-R) provide the ADJ terminal. Attempting external feedback will not alter output voltage and may destabilize regulation.

Is a heat sink mandatory for continuous 3 A operation?

Yes-using the TO-220 package at 3 A with 5 V input (1.7 W dissipation) requires a heatsink achieving ≤25 °C/W junction-to-ambient thermal resistance to stay within the 125 °C max junction temperature. Without a heatsink, ambient temperature must remain ≤50 °C for safe operation.

Does LD1085V36 support reverse polarity or reverse current protection?

No-LD1085V36 has no built-in reverse polarity or reverse current protection. If VIN drops below VOUT (e.g., during power-down), current can flow backward from output to input, potentially damaging upstream circuitry. An external Schottky diode in series with VIN is recommended for such scenarios.