STMicroelectronics LD1117DT18TR

Overview

LD1117DT18TR from STMicroelectronics is a fixed-output 1.8 V, low-dropout linear voltage regulator delivering up to 800 mA output current with 1.0 V typical dropout at 100 mA. It features ±1 % output voltage tolerance at 25 °C, 75 dB supply voltage rejection at 120 Hz, and internal thermal/current limiting. It powers microcontroller core rails, FPGA I/O banks, and industrial sensor signal chains requiring stable 1.8 V bias under varying load and input conditions.

For engineers reviewing the LD1117DT18TR datasheet, LD1117DT18TR pinout, LD1117DT18TR application, or LD1117DT18TR equivalent, key selection criteria include dropout voltage at full load, output accuracy over temperature, thermal resistance in SOT-223, minimum required output capacitance (10 µF), and compatibility with ceramic capacitors for space-constrained PCBs.

Technical Context

The LD1117DT18TR uses an NPN pass transistor architecture, enabling high efficiency by routing quiescent current primarily into the load rather than ground. Its internal bandgap reference and error amplifier maintain regulation across 0–125 °C junction temperature with ≤0.5 % temperature-induced drift.

Stability is achieved with only a 10 µF output capacitor-no ESR requirement-supporting low-ESR ceramic types. The device integrates foldback current limiting and thermal shutdown, activating at ~165 °C junction temperature and recovering after cooldown.

Key Specifications

Pinout & Package

LD1117DT18TR is supplied in SOT-223 package (TO-261AA), with exposed thermal pad electrically connected to V_OUT. This configuration enables direct thermal coupling to PCB copper for enhanced power dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-18CDCYR and AP1117D18G-13, LD1117DT18TR offers superior dropout performance and tighter output accuracy-enabling robust operation from marginal input sources and supporting high-precision analog subsystems without additional compensation.

Availability

LD1117DT18TR is available at Aetrix Electronics and suitable for industrial automation controllers, wearable health sensors, automotive body electronics, and network edge gateways requiring stable component supply with full production lifecycle support.

Supply support for LD1117DT18TR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

LD1117 belongs to ST's standard linear regulator product line, engineered for cost-sensitive, high-volume applications demanding reliability, thermal robustness, and ease of integration in space-constrained PCBs.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 800 mA?

The LD1117DT18TR requires a minimum input voltage of 2.9 V to maintain regulation at 800 mA load, based on its 1.1 V maximum dropout voltage specification at that current. Operation below this threshold causes output collapse; design margin should include worst-case dropout (1.2 V) and input ripple.

Can ceramic capacitors be used for input and output filtering?

Yes-only a 10 µF ceramic capacitor is required on the output for stability, with no ESR constraints. A 1 µF ceramic capacitor is recommended on the input, placed within 5 mm of the V_IN pin. Both X7R and X5R dielectrics are validated per ST's application notes.

Does LD1117DT18TR support reverse-voltage protection?

No-the device lacks internal reverse-battery protection. Applying reverse polarity to V_IN or V_OUT can cause latch-up or permanent damage. External protection (e.g., series Schottky diode or ideal diode controller) is required in battery-reversal-prone environments.

How does thermal performance differ between SOT-223 and DPAK packages?

SOT-223 has R_thJA = 110 °C/W; DPAK (TO-252) achieves 100 °C/W-offering ~9 % better ambient-to-junction thermal resistance. However, SOT-223's smaller footprint suits dense layouts, while DPAK allows higher continuous current in thermally constrained enclosures with minimal copper area.