Texas Instruments LMS8117AMP-ADJ

Overview

LMS8117AMP-ADJ from Texas Instruments is a 1-A adjustable-output low-dropout linear regulator with 1.25-V internal reference, 1.25-V typical dropout at 1 A, ±1% output voltage accuracy, and thermal/current protection. It serves as a post-regulator for DC-DC converters in industrial power supplies requiring stable local regulation.

For engineers reviewing the LMS8117AMP-ADJ datasheet, LMS8117AMP-ADJ pinout, LMS8117AMP-ADJ application, or LMS8117AMP-ADJ equivalent, key selection criteria include dropout voltage at full load, ADJUST pin current (60 µA typ), minimum 10-µF tantalum output capacitance requirement, and SOT-223 package thermal resistance (61.4°C/W).

Technical Context

The LMS8117AMP-ADJ uses a Zener-trimmed band-gap reference to maintain ±1% output voltage accuracy across 0°C to 125°C. Its adjustable architecture relies on two external resistors to set VOUT from 1.25 V to 13.8 V via the ADJUST pin, where VREF = 1.25 V is held between OUTPUT and ADJUST terminals.

It integrates current limiting (1–1.9 A) and thermal shutdown for fault protection. The device operates with input voltages up to 15 V and requires ≥1.25 V headroom (VIN – VOUT) for regulation, enabling operation down to 2.5 V input when regulating 1.25 V output.

Key Specifications

Pinout & Package

Package: SOT-223 (DCY), 3.50 mm × 6.50 mm body, with exposed thermal pad connected to OUTPUT pin (Pin 4). Pin 4 serves dual role as OUTPUT terminal and heatsink interface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM1117MPX-ADJ/NOPB and TLV1117-ADJ, the LMS8117AMP-ADJ offers superior thermal robustness (125°C operation), higher PSRR for noisy supply environments, and guaranteed ADJUST pin current (60 µA) essential for precision resistor-divider designs - making it optimal for industrial and instrumentation applications demanding long-term stability and wide-temperature reliability.

Availability

LMS8117AMP-ADJ is available at Aetrix Electronics and suitable for industrial PLCs, battery-powered test equipment, and embedded microprocessor power supplies requiring stable component supply across multi-year production cycles.

Supply support for LMS8117AMP-ADJ 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, embedded processing, and power management ICs, with decades of expertise in high-reliability linear regulation technology.

The LMS8117A product line was designed for high-accuracy, thermally robust local regulation in industrial, automotive, and instrumentation systems - emphasizing dropout performance, output stability, and integrated fault protection.

FAQ

What is the minimum input-to-output voltage difference required for regulation in the LMS8117AMP-ADJ?

The LMS8117AMP-ADJ requires a minimum headroom of 1.25 V (VIN – VOUT) to maintain regulation at full 1-A load across 0°C to 125°C. At lighter loads, dropout drops to 1.1 V. This enables use with Li-ion batteries (3.0–4.2 V) to generate stable 1.8-V or 3.3-V rails without violating regulation limits. Always verify worst-case dropout using the datasheet's Figure 1 curve under actual junction temperature conditions.

Can the LMS8117AMP-ADJ be used with ceramic output capacitors?

The LMS8117AMP-ADJ is optimized for 10-µF tantalum capacitors with 0.5–5 Ω ESR and is not guaranteed stable with low-ESR ceramic capacitors. Using ceramics may cause oscillation due to insufficient phase margin. If ceramic capacitors are mandatory, add a 1-Ω damping resistor in series with the capacitor or use a hybrid approach (tantalum + ceramic) with the tantalum meeting minimum ESR requirements.

How does the ADJUST pin current affect output voltage accuracy in the LMS8117AMP-ADJ?

The LMS8117AMP-ADJ ADJUST pin draws 60 µA (typical), which flows through R2 in the feedback divider and introduces a voltage error term (I_ADJ × R2) in the output equation VOUT = VREF × (1 + R2/R1) + (I_ADJ × R2). For R2 = 1 kΩ, this adds ~60 mV error - mitigated by selecting R1/R2 values that keep I_ADJ × R2 < 1% of target VOUT, e.g., R2 ≤ 125 Ω for 1.25-V output.

What thermal considerations apply to the LMS8117AMP-ADJ in SOT-223 package?

The LMS8117AMP-ADJ in SOT-223 has RθJA = 61.4°C/W (with 1-oz copper). At 1 A and 5-V dropout (5 W dissipation), junction temperature rise is 307°C - exceeding 125°C absolute max. Real-world design requires ≥4 cm² copper pour under the thermal pad and careful ambient derating. Use TI's Figure 19 to determine safe power limits at your target ambient temperature and PCB copper area.

Is the LMS8117AMP-ADJ pin-compatible with the LM317?

Yes, the LMS8117AMP-ADJ shares identical pinout (ADJUST, OUTPUT, INPUT) and footprint compatibility with the LM317 in SOT-223, enabling drop-in replacement in existing designs. However, it improves upon the LM317 with lower dropout (1.25 V vs. 2 V), tighter output tolerance (±1% vs. ±3%), and integrated thermal/current protection - requiring no external safety components.