STMicroelectronics LD1117S25TR

Overview

LD1117S25TR from STMicroelectronics is a fixed-output 2.5 V low-dropout linear voltage regulator in SOT-223 package, delivering up to 800 mA output current with 1.1 V typical dropout at 800 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, sensors, and analog circuitry requiring stable 2.5 V supply.

For engineers reviewing the LD1117S25TR datasheet, LD1117S25TR pinout, LD1117S25TR application, or LD1117S25TR equivalent, key selection considerations include dropout voltage under full load, thermal resistance (R_thJA = 110 °C/W), minimum load requirement (2–5 mA), stability with 10 µF ceramic output capacitor, and compatibility with standard 2.5 V logic and ADC reference domains.

Technical Context

The LD1117S25TR uses 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 tight regulation across line, load, and temperature variations.

It integrates thermal shutdown and current limiting, operates over input voltages up to 15 V, and achieves stable regulation with only a 10 µF minimum output capacitance-no ESR constraints required. The device is specified for operation from −40 °C to +125 °C junction temperature in the C-grade version.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal pad connected internally to V_OUT; requires soldering pad to PCB copper for thermal performance. Pin 1 = IN, Pin 2 = OUT, Pin 3 = GND, Pin 4 = TAB (V_OUT).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDCYR, LD1117S25TR offers tighter voltage accuracy and lower dropout, making it superior for precision analog rails; versus MCP1703T-2502E/MB, it delivers 3.2× more current but consumes ~2000× more quiescent current-highlighting the trade-off between dynamic capability and static power.

Availability

LD1117S25TR is available at Aetrix Electronics and suitable for industrial control panels, medical diagnostic handhelds, and IoT edge gateways requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LD1117S25TR 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 general-purpose linear regulator product line, engineered for cost-sensitive, high-reliability applications demanding robust thermal behavior, wide input range, and minimal external components.

FAQ

Is LD1117S25TR compatible with ceramic output capacitors?

Yes-LD1117S25TR is explicitly designed for stability with 10 µF or greater ceramic capacitors and imposes no minimum ESR requirement. This eliminates the need for bulkier, less reliable tantalum or aluminum electrolytic capacitors and simplifies layout in space-constrained designs.

What is the minimum load current required for regulation?

The LD1117S25TR requires a minimum load current of 2–5 mA to maintain regulation across temperature and line conditions. This is typically satisfied by MCU I/O leakage, pull-up resistors, or dedicated 1–2 kΩ load resistors-no active load circuitry is needed.

Can LD1117S25TR be used in parallel for higher current?

No-LD1117S25TR lacks built-in current-sharing features and is not characterized for parallel operation. Attempting parallel connection risks thermal runaway due to mismatched dropout voltages and thermal coefficients; use a single higher-current regulator instead.

Does LD1117S25TR support reverse-voltage protection?

No-the device has no internal reverse-battery or reverse-polarity protection. Applying reverse voltage on IN or OUT can cause latch-up or permanent damage. External protection (e.g., series Schottky diode on input) is required in systems prone to polarity reversal.