Texas Instruments LP3982IMMX-1.8

Overview

LP3982IMMX-1.8 from Texas Instruments (formerly National Semiconductor) is a fixed-output 1.8V, 300mA micropower ultra low-dropout CMOS linear regulator in an 8-pin MSOP package. It delivers ±2% output voltage tolerance, 120mV typical dropout at full load, 90µA typical quiescent current, and 37µV_RMS output noise (10Hz–100kHz), enabling efficient power delivery in space-constrained, battery-powered systems such as portable DSP cores and wireless handsets.

For engineers reviewing the LP3982IMMX-1.8 datasheet, LP3982IMMX-1.8 pinout, LP3982IMMX-1.8 application, or LP3982IMMX-1.8 equivalent, key selection criteria include its 1nA shutdown current, PMOS pass transistor architecture, stability with 2.2µF ceramic output capacitors, FAULT pin for regulation monitoring, and compatibility with Maxim MAX8860 footprint and electrical behavior.

Technical Context

The LP3982IMMX-1.8 employs a PMOS pass transistor topology with internal 1.25V bandgap reference and error amplifier feedback control, eliminating external drive current requirements and enabling ultra-low quiescent operation. Its internally generated compensation zero ensures stability with low-ESR ceramic capacitors as small as 2.2µF - a critical advantage over traditional PNP-based LDOs.

Regulation fault detection is implemented via an open-drain FAULT pin that asserts low during thermal shutdown, current limit, or input-to-output differential approaching dropout. The SHDN pin supports logic-level control with 0.4V max low threshold and 2V min high threshold, enabling seamless integration into battery-monitoring circuits with micropower comparators.

Key Specifications

Pinout & Package

LP3982IMMX-1.8 is housed in an 8-pin MSOP (Micro Small Outline Package) with 0.65mm pitch, measuring 3.0mm × 3.0mm × 1.0mm. This thermally enhanced surface-mount package supports PCB trace-area thermal dissipation and is pin-compatible with Maxim MAX8860.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3982IMMX-1.8, MAX8860EUB+T offers direct mechanical and electrical interchangeability but with marginally reduced dropout performance, while TLC7701QDR trades noise/size efficiency for automotive reliability - making LP3982IMMX-1.8 optimal for high-density, battery-limited consumer electronics where ultra-low IQ and noise are decisive.

Availability

LP3982IMMX-1.8 is available at Aetrix Electronics and suitable for wireless handset power, DSP core supply, and battery-powered IoT node applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LP3982IMMX-1.8 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 LP3982IMMX-1.8 belongs to TI's legacy micropower LDO family, originally designed for ultra-low-noise, ultra-low-I_Q power delivery in portable communications and computing devices where battery life and signal integrity are critical.

FAQ

What is the maximum input voltage for LP3982IMMX-1.8?

The absolute maximum input voltage for LP3982IMMX-1.8 is 6.5V, but the recommended operating range is 2.5V to 6.0V. Exceeding 6.5V risks permanent damage per Absolute Maximum Ratings. Within the 2.5–6.0V range, LP3982IMMX-1.8 maintains regulation, PSRR, and thermal safety across its full −40°C to +85°C junction temperature range.

Does LP3982IMMX-1.8 require an external output capacitor, and what value is recommended?

Yes, LP3982IMMX-1.8 requires an external output capacitor for stability. The datasheet specifies 2.2µF ceramic (X5R/X7R) as the minimum stable value; larger values (e.g., 4.7µF–10µF) improve transient response without compromising stability. LP3982IMMX-1.8's internal compensation eliminates ESR dependency, unlike many older LDOs that mandate tantalum capacitors.

How does the FAULT pin on LP3982IMMX-1.8 function, and what external components are needed?

The FAULT pin on LP3982IMMX-1.8 is an open-drain output that pulls low during thermal shutdown, current limit, or when input-to-output differential approaches dropout. It requires an external pull-up resistor - typically 100kΩ to V_IN or system logic rail - to generate a valid logic-high signal when regulation is healthy. No other passive components are required for basic fault indication.

Can LP3982IMMX-1.8 be used in place of MAX8860 in an existing design?

Yes, LP3982IMMX-1.8 is explicitly designed as pin-, package-, and specification-compatible with Maxim MAX8860 for 1.8V versions. Electrical parameters including dropout, quiescent current, noise, and FAULT behavior align closely. However, verify FAULT pin logic polarity and startup timing in your specific application, as minor behavioral differences exist in edge cases.

What is the purpose of the CC pin on LP3982IMMX-1.8, and what capacitor should be used?

The CC pin on LP3982IMMX-1.8 connects directly to the internal bandgap reference and accepts a noise-bypass capacitor to reduce output voltage noise. A 33nF NPO or COG ceramic capacitor is optimal - it lowers RMS noise from 37µV to ~25µV without degrading start-up time or transient response. Avoid high-leakage dielectrics (e.g., Y5V) that could load the reference and shift output voltage.