STMicroelectronics LD1086DTTR

Overview

LD1086DTTR from STMicroelectronics is a 1.5 A low-dropout positive voltage regulator in DPAK package, offering fixed 3.3 V output with ±1% tolerance at 25 °C and ±2% over –40 °C to +125 °C. It delivers guaranteed 1.5 A output current with typical dropout of 1.3 V at full load, internal thermal and power limiting, and requires only a 10 µF output capacitor for stability. It is used in industrial power supplies, embedded system rails, and automotive body control modules where compact, thermally robust regulation is required.

For engineers reviewing the LD1086DTTR datasheet, LD1086DTTR pinout, LD1086DTTR application, or LD1086DTTR equivalent, key selection criteria include dropout voltage at 1.5 A, output tolerance across temperature, thermal resistance (R_thJA = 33 °C/W in DPAK), minimum load current (3–10 mA), and adjust-pin current behavior (40–120 µA) when used in adjustable configurations.

Technical Context

The LD1086DTTR implements an NPN-based LDO architecture with on-chip trimmed bandgap reference (1.25 V nominal), enabling tight output tolerance without external resistor networks for fixed versions. Its quiescent current flows into the load-not wasted as base current-improving efficiency versus legacy PNP regulators.

It integrates thermal shutdown and current limiting, with dropout voltage remaining stable across temperature (≤1.5 V max at 1.5 A, –40 °C to +125 °C) and line/load regulation specified down to 0.1% typical. The DPAK package provides 33 °C/W junction-to-ambient thermal resistance, supporting continuous 1.5 A operation with moderate heatsinking.

Key Specifications

Pinout & Package

LD1086DTTR uses the DPAK (TO-252) surface-mount package with exposed thermal pad connected to output (V_OUT). Pin 1 = Input (IN), Pin 2 = Ground (GND), Pin 3 = Output (OUT). The tab is electrically tied to the output pin, requiring isolation from PCB ground plane unless output is referenced to ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-33CDCR and TPS7A4701RGWR, LD1086DTTR uniquely balances high output current (1.5 A), low thermal resistance (33 °C/W), and fixed 3.3 V accuracy in a standard DPAK footprint - making it optimal for thermally demanding industrial and automotive digital power rails where alternatives require trade-offs in current, thermal performance, or package compatibility.

Availability

LD1086DTTR is available at Aetrix Electronics and suitable for industrial PLC I/O power rails, automotive body control modules, and embedded system core rails requiring stable component supply with automotive-grade traceability and extended temperature support.

Supply support for LD1086DTTR 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, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD1086 series belongs to ST's high-current linear regulator product line, engineered specifically for robust, thermally efficient voltage regulation in harsh-environment applications such as automotive ECUs and industrial automation hardware.

FAQ

Is LD1086DTTR pin-compatible with LM317-based designs?

Yes - LD1086DTTR uses the same DPAK pinout (IN-GND-OUT) as industry-standard adjustable regulators like LM317, enabling direct replacement in existing layouts. However, it is a fixed 3.3 V device, so feedback resistors must be removed or bypassed; the ADJ pin is internally connected to GND in this variant.

What is the minimum input voltage required for regulation at 1.5 A?

The minimum input voltage is 4.6 V: 3.3 V output + 1.3 V typical dropout. At worst-case 1.5 V dropout (per datasheet limit), input must be ≥4.8 V. Input voltage must remain ≤30 V to avoid absolute maximum rating violation.

Can LD1086DTTR be used without an input capacitor?

No - while the datasheet specifies only a 10 µF output capacitor for stability, an input capacitor (≥1 µF ceramic) is strongly recommended to suppress source impedance effects and prevent oscillation during line transients. Omitting it risks instability under dynamic load conditions.

Does the thermal pad on the DPAK package require soldering to PCB copper?

Yes - the exposed thermal pad is electrically connected to the output (V_OUT) and is essential for thermal performance. It must be soldered to a dedicated copper pour (≥250 mm² recommended) with ≥4 thermal vias to inner/ground layers to achieve the rated R_thJA = 33 °C/W.