Texas Instruments LP3982ILDX-3.3

Overview

LP3982ILDX-3.3 from Texas Instruments (formerly National Semiconductor) is a micropower, ultra low-dropout, low-noise CMOS linear regulator delivering 300mA output current with 3.3V fixed output, 120mV typical dropout at full load, 90µA typical quiescent current, and 37µV_RMS output noise (10Hz–100kHz). It serves as a primary power supply for DSP cores and RF front-ends in space-constrained portable electronics.

For engineers reviewing the LP3982ILDX-3.3 datasheet, LP3982ILDX-3.3 pinout, LP3982ILDX-3.3 application, or LP3982ILDX-3.3 equivalent, key selection criteria include its 1nA shutdown current, stability with 2.2µF ceramic output capacitors, ±2% output voltage tolerance, fault detection capability, and compatibility with Maxim MAX8860 footprint and electrical behavior.

Technical Context

The LP3982ILDX-3.3 employs a PMOS pass transistor architecture enabling ultra-low dropout and near-zero drive current consumption-unlike PNP-based LDOs. Its internal bandgap reference and error amplifier provide precise regulation, while an internally generated compensation zero ensures stability with low-ESR ceramic capacitors as small as 2.2µF.

It integrates regulation fault detection via open-drain FAULT pin (active low at ~120–280mV input–output differential), thermal shutdown at 160°C with 10°C hysteresis, and constant-current limiting (330–770mA). The SHDN pin enables logic-controlled sleep mode with 1nA supply current.

Key Specifications

Pinout & Package

LP3982ILDX-3.3 is housed in an 8-pin LLP (Leadless Leadframe Package), 3mm × 3mm × 0.8mm body, thermally enhanced for high-current operation in compact layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3982ILDX-3.3, MAX8860EUB33+T offers drop-in replacement convenience but sacrifices 33% higher quiescent current and lacks fault signaling; TLC7733IPW provides wider temperature range but requires larger output capacitance and delivers no diagnostic capability-making LP3982ILDX-3.3 optimal for battery-powered, noise-critical, and safety-aware designs.

Availability

LP3982ILDX-3.3 is available at Aetrix Electronics and suitable for wireless handsets, DSP core power supplies, and portable instrumentation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LP3982ILDX-3.3 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 precision analog and power management portfolio. TI is a global semiconductor leader focused on analog, embedded processing, and connectivity solutions.

The LP3982ILDX-3.3 belongs to National's micropower LDO family designed specifically for battery-powered portable electronics demanding ultra-low quiescent current, low noise, and minimal board area-targeting applications where every microamp and square millimeter matters.

FAQ

What is the maximum input voltage rating for LP3982ILDX-3.3?

The absolute maximum input voltage for LP3982ILDX-3.3 is 6.5V, but the recommended operating range is 2.5V to 6.0V per the datasheet. Exceeding 6.5V risks permanent damage. For reliable operation across temperature, maintain VIN ≤ VO + 0.5V minimum headroom unless operating at light loads; the LP3982ILDX-3.3 achieves 120mV dropout at 300mA, so 3.42V input sustains 3.3V output under full load.

Does LP3982ILDX-3.3 require an external bypass capacitor on the CC pin?

Yes, LP3982ILDX-3.3 requires a 33nF NPO or COG ceramic capacitor between Pin 6 (CC) and ground to achieve its specified 37µV_RMS output noise. Omitting this capacitor increases broadband noise by ~2×. The CC pin connects directly to the bandgap reference node, and low-leakage dielectrics prevent reference loading-polypropylene film caps may be used but offer no advantage over NPO/COG ceramics in size or cost.

How does the FAULT pin on LP3982ILDX-3.3 behave during thermal shutdown?

During thermal shutdown, the FAULT pin on LP3982ILDX-3.3 asserts low (≤0.25V at 2mA sink) as soon as junction temperature reaches ~160°C. It remains low until the die cools by ~10°C hysteresis, then releases high-impedance (open-drain). This behavior is identical for overcurrent and pre-dropout conditions. An external 100kΩ pull-up resistor to VIN or VOUT is mandatory to establish valid logic-high state when FAULT is inactive.

Can LP3982ILDX-3.3 operate stably with a 1µF ceramic output capacitor?

No-LP3982ILDX-3.3 is characterized and guaranteed stable only with ≥2.2µF ceramic output capacitance (X5R/X7R dielectric). Using 1µF violates the minimum stability requirement and risks oscillation under load transients. The internal zero compensation is tuned for 2.2µF; smaller values shift phase margin into instability. If board space is constrained, use a 2.2µF 0402 X7R capacitor-widely available and footprint-compatible with most 0603 layouts.

Is LP3982ILDX-3.3 pin-compatible with the MSOP-8 version LP3982IMMX-3.3?

No-LP3982ILDX-3.3 (8-pin LLP) and LP3982IMMX-3.3 (8-pin MSOP) share identical pin functions and signal assignments but differ mechanically: LLP has bottom-exposed thermal pad and no leads, while MSOP has gull-wing surface-mount leads. They are not interchangeable on the same PCB footprint. Layouts must be redesigned for thermal via placement (LLP) versus lead pitch (MSOP); however, schematic symbols and net connectivity are identical.