STMicroelectronics LD1117V33C

Overview

LD1117V33C from STMicroelectronics is a fixed-output 3.3 V low-dropout linear voltage regulator 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 at 120 Hz. It serves as a primary post-regulator in embedded power rails for microcontrollers, sensors, and communication interfaces requiring stable 3.3 V supply under varying load and input conditions.

For engineers reviewing the LD1117V33C datasheet, LD1117V33C pinout, LD1117V33C application, or LD1117V33C equivalent, key selection considerations include dropout voltage at full load, thermal resistance in SOT-223 package, minimum load requirement (2–5 mA), stability with 10 µF ceramic output capacitor, and compatibility with industrial temperature range (−40 °C to +125 °C).

Technical Context

The LD1117V33C 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.

On-chip trimming achieves ±1 % initial output accuracy at 25 °C, while thermal shutdown and current limiting protect against fault conditions. The device operates with only a 10 µF output capacitor and requires no external compensation, simplifying layout in space-constrained applications.

Key Specifications

Pinout & Package

LD1117V33C is commonly supplied in SOT-223 package, where the exposed tab is electrically connected to V_OUT and serves as the primary thermal path to the PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-33CDCR, LD1117V33C offers tighter initial tolerance and SOT-223 thermal performance; versus MCP1703T-3302E/MB, it delivers 3.2× higher current in a thermally robust package but requires more board area.

Availability

LD1117V33C is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, medical instrumentation, and IoT edge node designs requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for LD1117V33C 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, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The LD1117 series belongs to ST's standard linear regulator product line, engineered for cost-sensitive, high-reliability applications demanding robust thermal behavior, wide input voltage range, and minimal external components.

FAQ

What is the minimum load current required for stable regulation?

The LD1117V33C requires a minimum load current of 2–5 mA to maintain regulation across temperature and line conditions. This is due to internal biasing requirements of the NPN pass transistor and error amplifier. Applications with light or zero-load conditions must add a bleed resistor (e.g., 680 Ω to 1.5 kΩ from V_OUT to GND) to meet this specification and prevent output voltage overshoot or instability.

Can LD1117V33C be used with ceramic output capacitors?

Yes-LD1117V33C is explicitly characterized and guaranteed stable with a minimum 10 µF X7R or X5R ceramic capacitor on the output. Unlike older LDOs, it does not require ESR-based damping, eliminating the need for tantalum or aluminum electrolytic capacitors. This reduces size, cost, and failure risk while improving long-term reliability in high-temperature environments.

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

In SOT-223, LD1117V33C has R_thJA = 110 °C/W (no copper pour) and R_thJC = 15 °C/W; in DPAK (TO-252), R_thJA = 100 °C/W and R_thJC = 8 °C/W. DPAK offers better junction-to-case conduction, making it preferable for >500 mA continuous loads on standard FR-4, while SOT-223 remains viable with ≥2 in² 2-oz copper pour for thermal relief.

Is there a pin-compatible adjustable version of LD1117V33C?

Yes-the LD1117ADJ is the adjustable variant, sharing identical pinout (IN, OUT, GND) and package options. It features a 1.25 V reference (V_REF) and requires two external resistors to set output voltage. While not drop-in compatible for fixed 3.3 V use, it enables design reuse across multiple output voltages using the same PCB footprint and thermal layout.