STMicroelectronics LD1117DT12CTR

Overview

LD1117DT12CTR 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 1.0 V typical dropout at 100 mA, ±1 % output voltage tolerance at 25 °C, and 75 dB supply voltage rejection at 120 Hz - used for post-regulation of 3.3 V or 5 V rails in embedded power supplies.

For engineers reviewing the LD1117DT12CTR datasheet, LD1117DT12CTR pinout, LD1117DT12CTR application, or LD1117DT12CTR equivalent, this page provides verified pin functions, thermal performance data, load/line regulation specs, stability requirements (10 µF min. output capacitor), and real-world use cases in industrial control modules and battery-backed microcontroller systems.

Technical Context

The LD1117DT12CTR uses an NPN pass transistor architecture, enabling high efficiency by routing most quiescent current into the load rather than ground - unlike PNP-based regulators. Its internal bandgap reference and trimming circuitry achieve ±1 % output accuracy at 25 °C and maintain ≤1 % load/line regulation over full operating conditions.

Thermal protection and current limiting are fully integrated; junction temperature is monitored on-die, and shutdown occurs above +125 °C. The device operates across -40 to +125 °C (C-grade) with input voltage range up to 15 V and requires only a single 10 µF ceramic or tantalum output capacitor for stability.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal pad connected internally to V_OUT; footprint optimized for surface-mount assembly and thermal dissipation in compact PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV70012DCKR and AP2202K-1.2TRG1, the LD1117DT12CTR uniquely balances high current delivery (800 mA), tight accuracy (±1 %), and robust thermal performance in SOT-223 - making it optimal for industrial embedded systems where reliability under load and temperature stress is non-negotiable.

Availability

LD1117DT12CTR is available at Aetrix Electronics and suitable for industrial PLCs, USB-powered sensor nodes, battery-backed RTC modules, and FPGA configuration supplies requiring stable component supply across long production lifecycles.

Supply support for LD1117DT12CTR 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.

The LD1117 series belongs to ST's high-reliability linear regulator product line, engineered specifically for cost-sensitive industrial and embedded applications demanding robust thermal behavior, wide input range, and long-term stability without external components.

FAQ

What is the minimum output capacitance required for stability?

The LD1117DT12CTR requires a minimum 10 µF output capacitor - ceramic or tantalum - with ESR between 0.1 Ω and 10 Ω. Lower values risk oscillation; higher ESR degrades transient response. ST recommends X5R/X7R ceramics for best performance and lifetime reliability.

Can LD1117DT12CTR be used with input voltages below 2.2 V?

No. The absolute minimum input voltage is 2.2 V (1.2 V output + 1.0 V dropout). Below this, regulation fails and output collapses. For sub-2.2 V operation, consider ultra-low-dropout regulators like TPS7A05 or MCP1700 with <100 mV dropout.

Is thermal pad connection mandatory for SOT-223 package?

Yes. The exposed tab (Pin 1) is electrically connected to V_OUT and serves as the primary thermal path. It must be soldered to ≥100 mm² copper area with ≥4 thermal vias to inner ground planes to maintain junction temperature within -40 to +125 °C limits at full 800 mA load.

Does LD1117DT12CTR support reverse-voltage protection?

No. The device lacks internal reverse-battery protection. If input polarity reversal is possible, add a series Schottky diode (e.g., BAT54) at the input - accepting its forward drop and power loss - or use an external protection IC like TPD2S017 before the LDO input.