Texas Instruments LP2985-18DBVRM3

Overview

LP2985-18DBVRM3 from Texas Instruments is a fixed 1.8V, 150mA low-dropout linear regulator in SOT-23-5 (DBV) package, featuring ±0.5% output accuracy (new chip), 30µVRMS output noise with 10nF bypass capacitor, 70dB PSRR at 1kHz, and shutdown current of 1.12µA - deployed in motor control boards and active antenna systems for clean, stable biasing of RF ICs and microcontrollers.

For engineers reviewing the LP2985-18DBVRM3 datasheet, LP2985-18DBVRM3 pinout, LP2985-18DBVRM3 application, or LP2985-18DBVRM3 equivalent, key selection criteria include dropout voltage at 150mA (≤198mV), thermal shutdown threshold (170°C), stability with 2.2µF ceramic output capacitors, and enable logic thresholds (0.15V low / 1.6V high) for reliable power sequencing in industrial embedded designs.

Technical Context

The LP2985-18DBVRM3 uses a CMOS pass transistor architecture with internal bandgap reference and error amplifier, enabling ultra-low dropout and precise regulation across –40°C to +125°C junction temperature. Its integrated soft-start reduces inrush current during startup, minimizing input capacitance requirements.

It implements active-high enable control with internal pulldown on disable, supports UVLO (2.2V rising, 1.9V falling), and delivers high PSRR (>70dB @ 1kHz, >40dB @ 1MHz) via bypass pin filtering - critical for post-regulating switching DC/DC outputs in noise-sensitive RF and MCU supply rails.

Key Specifications

Pinout & Package

LP2985-18DBVRM3 is housed in a 5-pin SOT-23 (DBV) package measuring 2.9mm × 2.8mm, optimized for thermal performance (R_θJA = 178.6°C/W) and PCB area efficiency in high-density layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and MCP1703T-1802E/MB, LP2985-18DBVRM3 delivers superior noise performance (30µVRMS), tighter regulation (±0.5%), and higher PSRR - making it optimal for RF and precision analog applications where supply integrity directly impacts signal fidelity.

Availability

LP2985-18DBVRM3 is available at Aetrix Electronics and suitable for motor drives, active antenna systems, washer/dryer controls, and land mobile radio designs requiring stable component supply, long-term manufacturability, and guaranteed parametric compliance.

Supply support for LP2985-18DBVRM3 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

LP2985-18DBVRM3 belongs to TI's LP2985 family of low-noise, low-dropout regulators designed specifically for noise-critical portable and infrastructure applications - emphasizing precision, thermal robustness, and ease of use in compact PCB layouts.

FAQ

What is the maximum input voltage rating for LP2985-18DBVRM3?

The LP2985-18DBVRM3 has an absolute maximum continuous input voltage of 18V per its revised datasheet (SLVS522S, May 2025). For reliable operation, the recommended input range is 2.5V to 16V. Exceeding 18V risks permanent damage, and operation below 2.5V may cause dropout or regulation loss. The device includes UVLO protection that disables output if VIN falls below 1.9V (falling) or 2.2V (rising).

Does LP2985-18DBVRM3 require an external bypass capacitor, and what value is recommended?

Yes, LP2985-18DBVRM3 requires an external capacitor on the BYPASS pin to achieve its specified 30µVRMS output noise. A 10nF ceramic capacitor connected between BYPASS and GND is explicitly recommended in the datasheet and validated in typical characteristics. Omitting this capacitor increases output noise significantly - measured data shows noise rises to ~100µVRMS without it - compromising performance in RF and precision analog applications.

Can LP2985-18DBVRM3 operate stably with a 2.2µF ceramic output capacitor?

Yes, LP2985-18DBVRM3 is explicitly characterized and guaranteed stable with a minimum 2.2µF ceramic output capacitor (X5R/X7R, 10% tolerance), provided its effective capacitance remains ≥1µF after DC bias and temperature derating. This is a key differentiator from legacy versions requiring 4.7µF. The datasheet confirms stability across ESR values up to 1Ω, and recommends adding a 100nF MLCC in parallel if higher-ESR capacitors are used.

What is the shutdown current specification for LP2985-18DBVRM3, and how is it measured?

The shutdown current for LP2985-18DBVRM3 is 1.12µA typical (max 2.75µA) when the ON/OFF pin is held ≤0.15V and VIN = 16V across –40°C to +125°C. This value is measured with the regulator fully disabled and output discharged via internal pulldown. It is significantly lower than legacy LP2985 variants (0.01µA typ), reflecting updated process and circuit design for improved deep-sleep efficiency in battery-powered systems.

Is LP2985-18DBVRM3 pin-compatible with other LP2985 variants such as LP2985-25DBVR?

Yes, LP2985-18DBVRM3 is pin-compatible with all LP2985 variants in the DBV (SOT-23-5) package, including LP2985-25DBVR and LP2985-33DBVR. All share identical pinout (VIN, GND, ON/OFF, BYPASS, VOUT), mechanical footprint, and thermal characteristics. The only functional difference is the fixed output voltage - 1.8V for LP2985-18DBVRM3 versus 2.5V or 3.3V for others - allowing direct substitution where voltage requirements align.