STMicroelectronics LD1117DT25TR

Overview

LD1117DT25TR from STMicroelectronics is a fixed-output 2.5 V low-dropout linear voltage regulator in DPAK (TO-252) 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 industrial power supplies and embedded microcontroller core rails.

For engineers reviewing the LD1117DT25TR datasheet, LD1117DT25TR pinout, LD1117DT25TR application, or LD1117DT25TR equivalent, key selection criteria include dropout voltage under full load, thermal resistance in DPAK, output accuracy across temperature, and minimum external capacitor requirements for stability.

Technical Context

The LD1117DT25TR 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 with only a 10 µF output capacitor.

It integrates thermal shutdown and current limiting, with guaranteed operation from −40 °C to +125 °C junction temperature. The DPAK package provides 8 °C/W junction-to-case thermal resistance, supporting continuous 800 mA output without forced airflow in typical PCB layouts.

Key Specifications

Pinout & Package

DPAK (TO-252) package with exposed thermal pad connected internally to V_OUT; requires soldered thermal pad for rated performance. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output (TAB = V_OUT).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDR and AP1117-25PG-13, the LD1117DT25TR delivers superior thermal management via its optimized DPAK thermal pad connection, tighter initial accuracy for analog subsystems, and higher PSRR-making it preferred for industrial and medical designs demanding long-term stability and ambient resilience.

Availability

LD1117DT25TR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical patient monitors, and IoT edge sensor hubs requiring stable component supply with full lifecycle support.

Supply support for LD1117DT25TR 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 specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and embedded markets.

The LD1117 series was designed to deliver high-current, low-dropout regulation in compact surface-mount packages for cost-sensitive yet thermally demanding applications-emphasizing robustness, ease of use, and wide operating temperature compliance.

FAQ

What is the minimum input voltage required for stable 2.5 V output at 800 mA?

The LD1117DT25TR requires a minimum input voltage of 3.6 V to maintain regulation at 800 mA, based on its 1.1 V typical dropout voltage. At 3.6 V input, the device sustains full 2.5 V output with ≤1 % deviation across −40 °C to +125 °C junction temperature, provided thermal design supports ≥4 W dissipation.

Can LD1117DT25TR replace adjustable LD1117 variants in existing designs?

No-LD1117DT25TR is a fixed 2.5 V output device with three-pin DPAK configuration (IN, GND, OUT). Adjustable versions require four pins (IN, OUT, GND, ADJ) and external resistor dividers. Substitution would demand PCB layout changes and loss of adjustability; only consider if the target application strictly requires 2.5 V and no future voltage flexibility is needed.

Is a bypass capacitor required on the adjustment pin? Does this part have an ADJ pin?

LD1117DT25TR has no adjustment pin-it is a fixed-output variant. Therefore, no ADJ pin bypass capacitor is needed or present. The device operates with only IN, GND, and OUT terminals; stability relies solely on the 10 µF output capacitor, per datasheet Figure 4.

How does the DPAK thermal pad connection affect reliability in high-vibration environments?

The DPAK thermal pad (connected to V_OUT) must be fully soldered to a large PCB copper pour using ≥50 % solder paste coverage and verified IPC-A-610 Class 2 voiding limits. In high-vibration applications, this mechanical and thermal bond prevents pad lifting, maintains thermal resistance within spec (8 °C/W), and avoids intermittent output failure caused by localized overheating at the die interface.