STMicroelectronics LD1117AV18

Overview

LD1117AV18 from STMicroelectronics is a low-dropout linear voltage regulator delivering fixed 1.8 V output at up to 1 A, with 1.15 V typical dropout at full load and ±2% output tolerance at 25 °C. It features internal current and thermal limiting, operates from 0 °C to 125 °C junction temperature, and requires only a 10 µF output capacitor for stability-commonly used in FPGA core supply rails and embedded microcontroller power domains.

For engineers reviewing the LD1117AV18 datasheet, LD1117AV18 pinout, LD1117AV18 application, or LD1117AV18 equivalent, key selection criteria include dropout voltage at 1 A, quiescent current under no-load conditions, thermal resistance in SOT-223 package, and supply voltage rejection at 120 Hz for noise-sensitive analog subsystems.

Technical Context

The LD1117AV18 employs an NPN pass transistor architecture enabling low dropout while maintaining high PSRR (80 dB typ. at 120 Hz) and low output noise (100 µV RMS, 10 Hz–10 kHz). Its reference is internally trimmed to 1.25 V, but the fixed 1.8 V version integrates resistive feedback for precise output without external components.

Thermal regulation is managed via on-die thermal shutdown and current limiting; R_thJA is 110 °C/W in SOT-223 and 50 °C/W in TO-220, directly impacting maximum continuous output current under ambient constraints. The device accepts input voltages up to 15 V DC but requires ≥3.3 V input for stable 1.8 V regulation across full load and temperature range.

Key Specifications

Pinout & Package

LD1117AV18 is supplied in SOT-223, DPAK (TO-252), and TO-220 packages. The SOT-223 variant is most common for surface-mount applications requiring moderate power dissipation and compact layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with TLV1117-18CDCR and AP1117-18SG-13, the LD1117AV18 offers superior thermal robustness (125 °C junction), tighter output tolerance (±2%), and lowest dropout (1.15 V), making it optimal for industrial and space-constrained embedded power rails where reliability and efficiency are prioritized.

Availability

LD1117AV18 is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive infotainment systems requiring stable component supply with long-term lifecycle assurance.

Supply support for LD1117AV18 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LD1117A series belongs to ST's standard linear regulator product line, engineered specifically for cost-sensitive, high-reliability embedded power applications requiring low dropout, minimal external components, and wide temperature operation.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 1 A?

The LD1117AV18 requires a minimum input voltage of 3.3 V to maintain regulation at 1 A load across the full temperature range. This accounts for the 1.30 V maximum dropout voltage at 1 A and 125 °C, ensuring sufficient headroom for worst-case thermal and process variation.

Can LD1117AV18 be used with ceramic output capacitors?

Yes-ST specifies stability with ≥10 µF ceramic, tantalum, or aluminum electrolytic capacitors. Ceramic capacitors are acceptable provided they meet the minimum capacitance and ESR requirements; no minimum ESR is mandated, unlike older LDO architectures.

Does LD1117AV18 include reverse-voltage protection?

No-the LD1117AV18 lacks built-in reverse-voltage protection. If input polarity reversal is possible in the system, an external series diode or MOSFET-based protection circuit must be added to prevent damage to the regulator or downstream circuitry.

How does thermal resistance differ between SOT-223 and TO-220 packages?

In SOT-223, R_thJA is 110 °C/W; in TO-220, it is 50 °C/W. This means the TO-220 package can dissipate ~2.2× more power before reaching thermal shutdown under identical ambient conditions, making it preferable for >500 mA continuous loads in poorly ventilated enclosures.