STMicroelectronics LD1117DT33TR

Overview

LD1117DT33TR from STMicroelectronics is a fixed-output 3.3 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 for post-regulation in microcontroller power rails, USB peripheral supplies, and industrial sensor interfaces.

For engineers reviewing the LD1117DT33TR datasheet, LD1117DT33TR pinout, LD1117DT33TR application, or LD1117DT33TR equivalent, key selection considerations include dropout voltage under load, thermal resistance in SOT-223 package, minimum load current requirement (2–5 mA), and stability with 10 µF ceramic output capacitor.

Technical Context

The LD1117DT33TR 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 trimmed feedback network achieve tight output regulation without external resistors.

Thermal protection and current limiting are fully integrated; the device shuts down under overtemperature or overload conditions and auto-recovers once safe limits are restored. It operates across –40 °C to +125 °C junction temperature and supports input voltages up to 15 V DC.

Key Specifications

Pinout & Package

LD1117DT33TR is housed in a surface-mount SOT-223 package with three terminals: Input (VIN), Ground (GND), and Output (VOUT). The exposed tab is electrically connected to VOUT and serves as the primary thermal path to the PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AMS1117-3.3, LD1117DT33TR offers tighter initial accuracy and lower dropout; versus TLV1117-33, it trades slightly higher quiescent current for broader industrial temperature support and proven robustness in high-reliability PCB layouts.

Availability

LD1117DT33TR is available at Aetrix Electronics and suitable for microcontroller power supplies, USB peripheral regulation, and industrial sensor interfaces requiring stable component supply with long-term manufacturing continuity.

Supply support for LD1117DT33TR 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The LD1117 series belongs to ST's general-purpose linear regulator product line, designed specifically for cost-sensitive, thermally constrained applications requiring high reliability and minimal external components.

FAQ

What is the minimum load current required for LD1117DT33TR stability?

The LD1117DT33TR requires a minimum load current of 2–5 mA to maintain regulation and avoid output voltage drift. This is satisfied by typical MCU I/O leakage, pull-up resistors, or a dedicated 1 kΩ–2.2 kΩ load resistor to ground. Failure to meet this condition may cause output overshoot or instability during light-load transients.

Can LD1117DT33TR be used with ceramic output capacitors?

Yes-LD1117DT33TR is explicitly designed for stability with 10 µF ceramic capacitors (X5R/X7R, ≤100 mΩ ESR). Unlike older LDOs, it does not require high-ESR tantalum or aluminum electrolytic capacitors, enabling smaller footprint, longer lifetime, and improved transient response in space-constrained designs.

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

SOT-223 has R_thJA = 110 °C/W, while DPAK achieves 100 °C/W-offering ~9 % better ambient-to-junction thermal resistance. However, SOT-223's smaller footprint and compatibility with standard reflow profiles make it preferred for high-density boards where PCB copper area is limited and airflow is controlled.

Is LD1117DT33TR compatible with lead-free reflow soldering processes?

Yes-LD1117DT33TR in SOT-223 package is qualified for standard lead-free reflow per JEDEC J-STD-020, with peak temperature up to 260 °C for 30 seconds. The device's plastic body and internal wirebond construction withstand multiple thermal cycles without parameter shift or delamination.