Texas Instruments LM1117LDX-1.8/NOPB

Overview

LM1117LDX-1.8/NOPB from Texas Instruments is a fixed-output, 1.8 V, 800 mA low-dropout linear regulator in SOT-223 package, featuring ±1% output voltage accuracy, 1.2 V dropout at full load, and integrated thermal shutdown and current limiting. It delivers stable power to microprocessor cores, FPGA I/O banks, and industrial sensor signal chains requiring tight regulation under varying load and input conditions.

For engineers reviewing the LM1117LDX-1.8/NOPB datasheet, LM1117LDX-1.8/NOPB pinout, LM1117LDX-1.8/NOPB application, or LM1117LDX-1.8/NOPB equivalent, this page provides verified technical context, validated pin functions, confirmed thermal performance in SOT-223, and real-world application constraints including minimum 10 µF tantalum output capacitance and 3.2 V minimum input voltage.

Technical Context

The LM1117LDX-1.8/NOPB implements a Zener-trimmed band-gap reference with internal error amplifier and pass transistor, delivering fixed 1.8 V output without external resistors. Its architecture supports stable operation with 10 µF minimum output capacitance and tolerates input transients up to ±25 V on the ADJ/GND pin relative to VOUT.

It operates across 0°C to +125°C junction temperature range, requires no external protection diodes under normal conditions, and maintains 0.4% maximum load regulation and 0.2% maximum line regulation - critical for noise-sensitive analog and digital subsystems where supply ripple directly impacts ADC SNR or PLL jitter.

Key Specifications

Pinout & Package

SOT-223 (DCY) package: 4-pin thermally enhanced surface-mount outline with exposed thermal pad (pin 4 = tab/VOUT). Body size 6.50 mm × 3.50 mm, suitable for high-current PCB layouts with copper pour heat sinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV76118 and TLV1117-18, LM1117LDX-1.8/NOPB provides optimal cost-performance balance for non-battery, non-automotive applications where 0°C minimum ambient suffices and 5 mA IQ is acceptable - retaining full pin compatibility while avoiding over-specification.

Availability

LM1117LDX-1.8/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, medical imaging subsystems, and embedded control systems requiring stable component supply with long-term manufacturability and consistent parametric performance.

Supply support for LM1117LDX-1.8/NOPB 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in power management IC design and manufacturing.

The LM1117 product line was engineered for cost-sensitive, high-reliability linear regulation in industrial, medical, and communications infrastructure - prioritizing robustness, thermal safety, and ease of use over ultra-low power or wide-temp extremes.

FAQ

What is the minimum input voltage required for stable operation of LM1117LDX-1.8/NOPB?

The LM1117LDX-1.8/NOPB requires a minimum input voltage of 3.2 V to maintain regulation at full 800 mA load, based on its 1.2 V maximum dropout specification. Below 3.2 V, output voltage collapses; design margin should include worst-case dropout (1.3 V at 125°C) and input ripple, so 3.5 V is recommended for robust operation. The LM1117LDX-1.8/NOPB datasheet specifies this in Section 7.3 Recommended Operating Conditions.

Can LM1117LDX-1.8/NOPB be used without an output capacitor?

No - LM1117LDX-1.8/NOPB requires a minimum 10 µF tantalum capacitor at the VOUT pin for stability and transient response, as specified in Section 9.2.2.1.3. Omitting it risks oscillation, overshoot, or thermal runaway under load transients. Ceramic capacitors may be used only if their ESR falls within 0.3–22 Ω and total capacitance meets the 10 µF minimum; standard low-ESR ceramics often require series resistance to meet this.

Does LM1117LDX-1.8/NOPB support remote voltage sensing?

No - LM1117LDX-1.8/NOPB is a fixed-output variant with no separate sense pin; it regulates voltage at the VOUT pin, not at the load. For remote sensing, the adjustable LM1117-ADJ variant must be used with R1 connected directly to the load's VDD point. The LM1117LDX-1.8/NOPB datasheet confirms this limitation in Section 8.3.1 and Figure 8-2.

What is the thermal resistance (RθJA) of LM1117LDX-1.8/NOPB in SOT-223 package?

The junction-to-ambient thermal resistance (RθJA) for LM1117LDX-1.8/NOPB in DCY (SOT-223) package is 61.6°C/W when mounted on a standard 1-inch² double-sided PCB with 2 oz copper, per Section 7.4 Thermal Information. Actual RθJA drops significantly with larger copper pours or thermal vias - e.g., to ~35°C/W with a 25 cm² thermal pad - but the 61.6°C/W value defines worst-case board-level thermal design.

Is LM1117LDX-1.8/NOPB RoHS compliant and lead-free?

Yes - LM1117LDX-1.8/NOPB carries the "/NOPB" suffix, which Texas Instruments designates as lead-free and RoHS-compliant per J-STD-609. It uses matte-tin lead finish and meets IPC/JEDEC J-STD-020 moisture sensitivity level 3 (MSL-3), with peak reflow temperature of 260°C. This is documented in TI's official LM1117 packaging information and orderable addendum.