STMicroelectronics LD1117V33

Overview

LD1117V33 from STMicroelectronics is a fixed-output 3.3 V low-dropout linear voltage regulator delivering up to 800 mA, featuring 1 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 supplies, industrial sensors, and embedded USB peripherals.

For engineers reviewing the LD1117V33 datasheet, LD1117V33 pinout, LD1117V33 application, or LD1117V33 equivalent, this page provides verified package mapping (SOT-223/TO-220/DPAK/SO-8), thermal resistance data (R_thJA = 110 °C/W for SOT-223), load regulation (≤10 mV), and real-world design meaning of dropout and noise specs.

Technical Context

The LD1117V33 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 trimming circuitry achieve tight output accuracy without external components.

Stability requires only a 10 µF output capacitor; no input capacitor is mandatory. The device integrates thermal shutdown and current limiting, with junction temperature operating range up to +125 °C for standard versions and –40 °C to +125 °C for "C" grade variants.

Key Specifications

Pinout & Package

LD1117V33 is available in SOT-223, TO-220, DPAK (TO-252), and SO-8 packages. The tab (exposed pad or metal slug) is electrically connected to V_OUT in all variants, serving as both thermal path and output terminal.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AMS1117-3.3 and TLV1117-33, LD1117V33 delivers superior output accuracy and ripple rejection in broader package choices - making it optimal for industrial and mixed-signal designs demanding reliability across temperature and layout variations.

Availability

LD1117V33 is available at Aetrix Electronics and suitable for microcontroller power supplies, industrial sensor nodes, USB peripheral interfaces, and embedded Wi-Fi module supplies requiring stable component supply across long production cycles.

Supply support for LD1117V33 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-effective, robust DC-DC conversion in space- and thermal-constrained embedded systems where simplicity and reliability are prioritized over ultra-low IQ.

FAQ

What is the minimum input voltage required for LD1117V33 to maintain regulation at 800 mA?

The maximum dropout voltage is 1.2 V at 800 mA and full temperature range. Therefore, minimum input voltage is 3.3 V + 1.2 V = 4.5 V. At 25 °C, dropout is typically 1.1 V, allowing operation down to 4.4 V - critical for single-cell Li-ion or 5 V rail derating scenarios.

Can LD1117V33 be used without an input capacitor?

Yes - the datasheet specifies no mandatory input capacitor. Stability relies solely on the 10 µF minimum output capacitor (with ESR ≤ 1 Ω). An input capacitor may improve transient response or reduce upstream noise but is not required for basic regulation or stability.

How does the exposed tab connection affect PCB layout?

The tab is internally connected to V_OUT, so any copper pour or thermal pad tied to the tab becomes part of the output net. This requires careful isolation from GND or other voltages. For SOT-223, the tab must be routed as V_OUT; for TO-220, the metal tab is V_OUT and must not contact heatsink unless insulated.

Is LD1117V33 suitable for powering RF circuits like Wi-Fi modules?

Yes - its 100 µV RMS output noise (10 Hz–10 kHz) and 75 dB supply rejection meet RF IC requirements. However, ensure adequate thermal management: at 300 mA load with 5 V input, power dissipation is ~0.5 W, requiring ≥2 cm² of 2-oz copper for SOT-223 to stay within safe junction temperature.