STMicroelectronics LD1117DT12TR

Overview

LD1117DT12TR from STMicroelectronics is a fixed-output 1.2 V low-dropout linear voltage regulator in SOT-223 package, delivering up to 800 mA output current with 1 V typical dropout at 100 mA, ±1 % output voltage tolerance at 25 °C, and 75 dB supply voltage rejection. It serves as a primary post-regulator in embedded power rails for microcontrollers and sensors requiring stable low-voltage bias.

For engineers reviewing the LD1117DT12TR datasheet, LD1117DT12TR pinout, LD1117DT12TR application, or LD1117DT12TR equivalent, key selection criteria include dropout voltage under load, thermal resistance (RthJA = 110 °C/W), minimum load requirement (2–5 mA), stability with 10 µF ceramic output capacitor, and compatibility with 15 V max input.

Technical Context

The LD1117DT12TR uses an NPN pass transistor architecture to minimize quiescent current consumption-most of which flows into the load rather than ground-enabling higher efficiency than PNP-based LDOs. Its internal bandgap reference (1.25 V) and trimming circuitry achieve tight output accuracy without external feedback components.

Thermal protection and current limiting are implemented on-die, with junction temperature operating range specified from 0 to +125 °C (standard version). The device requires only a single 10 µF output capacitor for stability across the full load and temperature range, eliminating need for ESR-tuned compensation networks.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal pad connected internally to VOUT; compact surface-mount footprint optimized for thermal performance and PCB area savings in space-constrained designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117S12TR, the LD1117DT12TR offers lower cost and identical electrical specs but lacks extended temperature rating; versus TLV1117-12CDCYR, it delivers superior dropout and ripple rejection at the expense of slightly higher quiescent current in light-load conditions.

Availability

LD1117DT12TR is available at Aetrix Electronics and suitable for industrial sensor nodes, USB peripheral power management, and automotive body electronics requiring stable component supply with consistent parametric performance across production batches.

Supply support for LD1117DT12TR 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 analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The LD1117 series belongs to ST's high-reliability linear regulator product line, engineered specifically for cost-sensitive, thermally constrained applications demanding tight output tolerance and robust built-in protection without external components.

FAQ

What is the minimum required output capacitance for stable operation?

The LD1117DT12TR requires a minimum 10 µF ceramic capacitor at the output for guaranteed stability across all load and temperature conditions. This value is validated per ST's test circuits and applies to X5R/X7R dielectrics with ≤2 Ω ESR. Using smaller values risks oscillation under dynamic load, especially above 500 mA.

Can LD1117DT12TR be used with input voltages below 2.2 V?

No. With a fixed 1.2 V output and 1.0 V typical dropout, the LD1117DT12TR requires ≥2.2 V input to maintain regulation. At 2.1 V input, output collapses to ≈1.1 V and regulation ceases. For sub-2.2 V inputs, consider ultra-low-dropout alternatives like ST's STLQ015 or Torex XC6210.

Is thermal pad connection mandatory for SOT-223 mounting?

Yes. The exposed tab (Pin 1) is electrically connected to VOUT and serves as the primary thermal path. It must be soldered to a ≥100 mm² copper pour with ≥4 thermal vias to inner ground planes. Omitting this compromises thermal resistance by >40 %, risking premature thermal shutdown at >400 mA continuous load.

Does LD1117DT12TR support reverse polarity protection?

No. The device lacks internal reverse-battery protection. Applying negative voltage to VIN relative to GND can damage the internal pass transistor. External protection-such as a series Schottky diode or dedicated reverse-polarity IC-is required in automotive or field-serviceable applications where incorrect battery connection is possible.