STMicroelectronics LD1117DT50CTR

Overview

LD1117DT50CTR from STMicroelectronics is a fixed-output 5.0 V, low-dropout linear voltage regulator 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 in post-regulation of switching power supplies and embedded microcontroller power rails.

For engineers reviewing the LD1117DT50CTR datasheet, LD1117DT50CTR pinout, LD1117DT50CTR application, or LD1117DT50CTR equivalent, key selection criteria include dropout voltage under load, thermal resistance in SOT-223 package, output voltage accuracy across temperature, and minimum external capacitor requirement (10 µF).

Technical Context

The LD1117DT50CTR employs an NPN pass transistor architecture, enabling high efficiency by routing quiescent current primarily into the load rather than ground-unlike PNP-based regulators. Its internal bandgap reference and error amplifier maintain regulation with only 10 µF output capacitance for stability.

It integrates thermal shutdown and current limiting, operates over −40 °C to +125 °C junction temperature (C-grade), and achieves ±1 % initial output accuracy via on-chip trimming-critical for precision analog and digital supply domains requiring tight voltage margins.

Key Specifications

Pinout & Package

LD1117DT50CTR is housed in a surface-mount SOT-223 package with exposed tab electrically connected to V_OUT for enhanced thermal conduction. The package features three signal pins plus thermal pad, optimized for compact PCB layouts and efficient heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-50CDCR, LD1117DT50CTR offers higher current and smaller SOT-223 footprint but higher thermal resistance; versus MCP1700T-5002E/TT, it delivers 3.2× more current at the cost of higher quiescent draw-making it optimal for industrial 5 V rail consolidation.

Availability

LD1117DT50CTR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body electronics, embedded microcontroller power rails, and consumer IoT sensor nodes requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for LD1117DT50CTR 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 standard linear regulator product line, engineered for cost-effective, thermally efficient, and highly stable local voltage regulation in space- and power-constrained embedded systems.

FAQ

What is the minimum input voltage required for LD1117DT50CTR to regulate 5.0 V at 800 mA?

The datasheet specifies a maximum dropout voltage of 1.2 V at 800 mA and 125 °C. To guarantee regulation across temperature and load, VIN must be ≥6.2 V. At room temperature, 6.0 V input is sufficient per typical 1.0 V dropout, but design margin requires 6.2 V minimum.

Can LD1117DT50CTR be used without an input capacitor?

No-while the datasheet does not specify a minimum input capacitance, ST recommends a 10 µF aluminum or tantalum capacitor at the input for transient response and stability, especially when the source impedance exceeds 1 Ω. Omitting it risks oscillation or poor line regulation during fast load steps.

Is the SOT-223 tab electrically isolated or connected to a pin?

The SOT-223 thermal tab is internally connected to the V_OUT pin (Pin 4), not isolated. It must be soldered to a PCB copper pour tied to the 5 V output net to ensure thermal performance and electrical integrity-never left floating or grounded.

How does LD1117DT50CTR handle reverse-voltage conditions on V_IN or V_OUT?

The device lacks reverse-battery or reverse-current protection. Applying reverse voltage to V_IN (e.g., −0.3 V) forward-biases internal junctions and may cause latch-up or permanent damage. External diodes are required if system-level reverse polarity exposure is possible.