Texas Instruments LP3982ILD-ADJ

Overview

LP3982ILD-ADJ from Texas Instruments (formerly National Semiconductor) is an adjustable-output, micropower ultra low-dropout CMOS linear regulator delivering 300mA output current with 120mV typical dropout at full load, 90µA typical quiescent current, and 37µV_RMS output noise (10Hz–100kHz). It operates from 2.5V to 6.0V input and supports output voltage adjustment from 1.25V to 6.0V via external resistors - ideal for battery-powered DSP core supplies requiring stable, low-noise bias under tight thermal and power budgets.

For engineers reviewing the LP3982ILD-ADJ datasheet, LP3982ILD-ADJ pinout, LP3982ILD-ADJ application, or LP3982ILD-ADJ equivalent, key selection criteria include its MSOP-8/LLP-8 package compatibility, ±2% output tolerance over load/temperature, fault detection capability, shutdown current of 1nA typ, and stability with 2.2µF ceramic output capacitors - all critical for portable, low-power embedded systems.

Technical Context

The LP3982ILD-ADJ employs a PMOS pass transistor architecture enabling true ultra-low dropout operation and eliminating base-drive current draw typical of PNP-based LDOs. Its internal 1.25V bandgap reference feeds an error amplifier that regulates output via external R1/R2 feedback network on the SET and OUT pins.

Stability is ensured by an internally generated compensation zero, allowing robust operation with low-ESR ceramic capacitors as small as 2.2µF - bypassing traditional ESR-dependent loop compensation. The device integrates fault detection (open-drain FAULT pin), thermal shutdown (160°C trip), and current limiting (330–770mA), all while maintaining no-load stability for RAM keep-alive use cases.

Key Specifications

Pinout & Package

LP3982ILD-ADJ is housed in an 8-pin LLP (Leadless Leadframe Package), 3mm × 3mm, 0.5mm pitch, thermally enhanced surface-mount package optimized for space-constrained portable designs. The LLP variant provides lower thermal resistance than MSOP-8 when properly laid out with thermal vias and copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79533DBVR and MAX8860ETE+, the LP3982ILD-ADJ uniquely balances adjustability, ultra-low IQ, integrated fault signaling, and ceramic-capacitor stability - making it optimal for battery-critical, noise-sensitive, and diagnostic-aware portable designs where layout space and thermal performance are constrained.

Availability

LP3982ILD-ADJ is available at Aetrix Electronics and suitable for wireless handsets, DSP core power supplies, and portable medical sensors requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for LP3982ILD-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 acquired National Semiconductor in 2011 and maintains its legacy analog portfolio, including precision power management ICs designed for high-reliability, low-power applications.

The LP3982ILD-ADJ belongs to TI's ultra-low-noise, micropower LDO family targeting battery-operated portable electronics where efficiency, compactness, and signal integrity are paramount.

FAQ

What is the minimum input voltage required for LP3982ILD-ADJ to regulate a 1.8V output?

The LP3982ILD-ADJ requires a minimum input voltage of 2.5V per its Absolute Maximum Ratings and Operating Ratings. To sustain 1.8V output, VIN must exceed VO + VDO - with typical dropout of 120mV at 300mA, this means VIN ≥ 1.92V in practice. However, the device is only specified to operate down to 2.5V input, so reliable regulation at 1.8V output begins at VIN = 2.5V. Below that, performance is not guaranteed.

Does LP3982ILD-ADJ require an external capacitor on the CC pin, and what happens if it's omitted?

Yes, LP3982ILD-ADJ requires a 33nF NPO or COG ceramic capacitor between the CC pin (Pin 6) and ground to achieve its specified 37µV_RMS output noise. Omitting it increases broadband noise by ~2× and degrades PSRR above 10kHz. The device remains functional and stable without CC, but noise-sensitive applications like ADC references or RF synthesizers will experience measurable SNR degradation.

Can LP3982ILD-ADJ be used with a 1µF output capacitor instead of the recommended 2.2µF?

No - the LP3982ILD-ADJ is characterized and guaranteed stable only with ≥2.2µF ceramic output capacitance. Using 1µF violates the minimum stability condition and risks oscillation under load transients or temperature variation. The datasheet explicitly specifies 2.2µF as the minimum value for stability across −40°C to +85°C, and no derating or test data support smaller values.

How does the FAULT pin on LP3982ILD-ADJ behave during thermal shutdown?

During thermal shutdown, the FAULT pin on LP3982ILD-ADJ asserts low (≤0.25V @ 2mA sink) as part of its integrated fault detection. This occurs concurrently with pass transistor disablement at ~160°C junction temperature. The FAULT signal remains low until both thermal recovery (≥10°C hysteresis) and regulation restoration occur - providing unambiguous system-level indication of thermal fault events without additional sensing circuitry.

Is LP3982ILD-ADJ pin-compatible with the MSOP-8 version LP3982IMM-ADJ?

No - LP3982ILD-ADJ uses an 8-pin LLP package (LDA08C), while LP3982IMM-ADJ uses an 8-pin MSOP package (MUA08A). Though both have identical pin functions and numbering, their footprints, thermal pad configurations, and solder reflow profiles differ. PCB layout, stencil design, and assembly processes are not interchangeable; separate land patterns and assembly validation are required for each package variant.