STMicroelectronics LD1086DT15R

Overview

LD1086DT15R from STMicroelectronics is a fixed-output 1.5 A low-dropout linear voltage regulator delivering 1.5 V with ±1% tolerance at 25 °C, 1.3 V typical dropout at full load, and operation across –40 °C to +125 °C. It uses a DPAK package with thermal protection, internal current limiting, and requires only a 10 µF output capacitor for stability - deployed in industrial power rails and embedded microcontroller core supplies.

For engineers reviewing the LD1086DT15R datasheet, LD1086DT15R pinout, LD1086DT15R application, or LD1086DT15R equivalent, this page provides verified pin functions, real-world load/line regulation values, thermal resistance data (R_thJA = 33 °C/W), automotive-grade alternatives, and design-meaningful specifications - all extracted from ST's production datasheet DocID6739 Rev 38.

Technical Context

The LD1086DT15R implements a PNP-based LDO architecture with on-chip trimming for tight output accuracy and a dedicated adjust pin (for adjustable variants) repurposed as GND in fixed versions. Its quiescent current flows into the load rather than being wasted, improving efficiency over legacy regulators.

It features internal thermal shutdown triggered at ~150 °C junction temperature and short-circuit current limiting that scales inversely with dropout voltage - delivering 1.5 A at 5 V input–output differential but reducing to 50 mA at 25 V differential - enabling robust operation under fault conditions.

Key Specifications

Pinout & Package

LD1086DT15R uses the DPAK (TO-252) surface-mount package with exposed thermal pad connected to the output terminal. The TAB is electrically tied to OUTPUT for enhanced thermal conduction to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1086DT25R, LD1086DT15R enables lower-power 1.5 V logic domains; compared with LD1086V15R, it offers cost-optimized performance for non-automotive systems without AEC-Q100 overhead.

Availability

LD1086DT15R is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, point-of-sale terminals, and automotive body control units requiring stable component supply across multi-year production cycles.

Supply support for LD1086DT15R 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, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

LD1086DT15R belongs to ST's LD1086 LDO family - engineered for high-current, low-dropout regulation in space-constrained applications where thermal performance and output accuracy are critical.

FAQ

What is the minimum input voltage required for LD1086DT15R to regulate at 1.5 V?

The minimum input voltage is 2.85 V - derived from the 1.3 V typical dropout plus 1.5 V output. At 1.5 A load, input must exceed 2.8 V to maintain regulation; derating is recommended above 100 °C ambient due to increased R_thJA.

Can LD1086DT15R replace an LM317 in an existing design?

No - the LD1086DT15R is a fixed 1.5 V device with three pins (IN/GND/OUT), while the LM317 is adjustable and requires two external resistors. However, it *is* pin-compatible with fixed-output variants like the LM2940-1.5, provided the DPAK footprint matches.

Does LD1086DT15R require an input capacitor?

Yes - ST recommends ≥1 µF ceramic or tantalum capacitor placed within 5 mm of the IN pin to prevent oscillation and improve transient response. Without it, line rejection degrades and startup instability may occur under fast input ramps.

Is the exposed thermal pad on the DPAK package electrically connected?

Yes - the TAB is internally bonded to the OUTPUT terminal. It must be soldered to a large copper pour tied to the output net for optimal thermal performance; floating or grounding the pad causes functional failure and thermal overstress.