STMicroelectronics LD1084D2M18R

Overview

LD1084D2M18R from STMicroelectronics is a fixed-output, 5A low-dropout linear voltage regulator delivering a precise 1.8V output with ±1% tolerance at 25°C and ±2% over −40°C to +125°C. It features a typical dropout voltage of 1.3V at full load, internal thermal and power limiting, and requires only a 10µF output capacitor for stability. It is used in high-current digital supply rails for FPGAs, ASICs, and microprocessors where tight regulation and thermal robustness are critical.

For engineers reviewing the LD1084D2M18R datasheet, LD1084D2M18R pinout, LD1084D2M18R application, or LD1084D2M18R equivalent, key selection criteria include dropout performance at 5A, output voltage accuracy across temperature, thermal resistance (R_thJC = 3°C/W), quiescent current behavior (5–10 mA), and compatibility with standard 3-terminal adjustable regulator footprints.

Technical Context

The LD1084D2M18R employs an NPN-based pass transistor architecture-unlike older PNP regulators-so its quiescent current flows into the load rather than being wasted, improving efficiency under light loads. Its internal trimming achieves ±1% initial output accuracy, and on-chip protection includes thermal shutdown and current limiting.

It operates across a 3.4V to 30V input range while maintaining regulation at 1.8V output up to 5A, with line regulation as low as 0.1 mV and load regulation of 3–7 mV (typical). The device supports stable operation with ceramic or tantalum output capacitors ≥10µF and exhibits 60–75 dB supply voltage rejection at 120 Hz.

Key Specifications

Pinout & Package

LD1084D2M18R is housed in a D2PAK (TO-263) surface-mount package with exposed thermal pad, optimized for high-power dissipation in compact layouts. Pin 1 is Input, Pin 2 is Ground, Pin 3 is Output - identical pinout to industry-standard 3-terminal adjustable regulators (e.g., LM317 footprint).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM1084IT-1.8/NOPB, LD1084D2M18R delivers superior thermal performance (3°C/W vs. 5°C/W) and load efficiency via load-directed quiescent current; versus TLV1117-18CDCYR, it provides 6.25× higher current capability and full industrial temperature qualification-making it the sole fit for high-power 1.8V system rails.

Availability

LD1084D2M18R is available at Aetrix Electronics and suitable for FPGA power delivery, industrial I/O modules, SCSI-2 termination circuits, and test equipment digital subsystems requiring stable component supply across long production lifecycles.

Supply support for LD1084D2M18R 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.

The LD1084 series belongs to ST's high-current linear regulator product line, engineered specifically for industrial-grade, high-reliability power conversion where low dropout, precision output, and rugged thermal performance are mandatory.

FAQ

What is the minimum input voltage required for LD1084D2M18R to regulate at 5A?

The minimum input voltage is calculated as V_OUT + V_DROP = 1.8 V + 1.5 V (max dropout) = 3.3 V. Per datasheet Table 4, regulation is guaranteed down to 3.4 V input at 5A across temperature, so 3.4 V is the validated minimum for full-load operation with margin.

Can LD1084D2M18R be used with ceramic output capacitors?

Yes-ST specifies stability with ≥10 µF ceramic or tantalum output capacitors. Unlike many older LDOs, it does not require ESR-based damping; low-ESR MLCCs are fully supported, reducing size and cost versus aluminum or tantalum alternatives.

Does LD1084D2M18R have reverse-voltage or reverse-current protection?

No. The device lacks integrated reverse-voltage or reverse-current blocking. If input can fall below output (e.g., during hot-swap or backup-battery switchover), an external Schottky diode from OUT to IN is recommended to prevent backfeed and potential damage.

How does thermal performance differ between D2PAK and TO-220 packages for this part?

Both packages share identical R_thJC = 3°C/W, but D2PAK offers lower R_thJA (62.5°C/W vs. 50°C/W for TO-220) due to its exposed pad. In practice, D2PAK achieves better PCB heat spreading-especially with 2+ oz copper and thermal vias-yielding up to 15% higher sustained current in constrained airflow environments.