Texas Instruments LP2985IM5X-6.1/NOPB

Overview

LP2985IM5X-6.1/NOPB from Texas Instruments is a fixed-output, micropower ultra-low-dropout linear regulator delivering 150 mA output current with 6.1 V nominal output voltage, 300 mV typical dropout at full load, 1% output voltage accuracy (A-grade), and 30 µV_RMS output noise (300 Hz–50 kHz) when using a 10-nF bypass capacitor. It serves as a precision, low-noise power supply for battery-powered portable electronics requiring stable rail generation under tight headroom constraints.

For engineers reviewing the LP2985IM5X-6.1/NOPB datasheet, LP2985IM5X-6.1/NOPB pinout, LP2985IM5X-6.1/NOPB application, or LP2985IM5X-6.1/NOPB equivalent, key selection considerations include its SOT-23-5 package footprint, ON/OFF logic-controlled shutdown (<2 µA quiescent), compatibility with low-ESR ceramic output capacitors (≥2.2 µF, ESR ≥5 mΩ), and thermal protection for sustained 150-mA operation in compact handheld systems.

Technical Context

The LP2985IM5X-6.1/NOPB employs a vertically integrated PNP (VIP) pass transistor architecture enabling ultra-low dropout (≤575 mV max at 150 mA/−40°C to 125°C) and low ground current (75 µA typ. at 1 mA, 850 µA typ. at 150 mA). Its internal reference and error amplifier are optimized for stability with ceramic capacitors down to 5 mΩ ESR, eliminating need for tantalum or aluminum electrolytic types.

It integrates active ON/OFF control (logic-high enable, 1.6 V min threshold), foldback current limiting (400 mA short-circuit, 350 mA peak), and thermal shutdown with automatic recovery. The BYPASS pin provides direct access to the internal reference node, allowing external 10-nF capacitor placement to suppress high-frequency noise and achieve 30 µV_RMS output noise performance.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm height, gull-wing leads. Designed for high-density, space-constrained PCBs in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and MCP1826T-6102E/DB, the LP2985IM5X-6.1/NOPB uniquely combines 1% accuracy, <2 µA shutdown, and 30 µV_RMS noise via BYPASS-making it optimal for battery-critical, noise-sensitive portable instrumentation where rail integrity directly impacts measurement validity.

Availability

LP2985IM5X-6.1/NOPB is available at Aetrix Electronics and suitable for portable medical sensors, wearable fitness trackers, industrial handheld scanners, and smart home sensor hubs requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for LP2985IM5X-6.1/NOPB 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 company designing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and consumer markets.

The LP2985-N product line delivers micropower, ultra-low-dropout regulators optimized for battery-powered portable electronics - emphasizing low noise, small footprint, and robust thermal/overcurrent protection in SOT-23 packaging.

FAQ

What is the minimum input voltage required for LP2985IM5X-6.1/NOPB to regulate 6.1 V output?

The LP2985IM5X-6.1/NOPB requires a minimum input voltage of 6.1 V plus its dropout voltage. At 150 mA and 25°C, dropout is typically 300 mV, so VIN ≥ 6.4 V is recommended. Over temperature (−40°C to 125°C), maximum dropout rises to 575 mV, requiring VIN ≥ 6.675 V for guaranteed regulation. The datasheet specifies a minimum recommended VIN of 3.1 V or VOUT + rated dropout - for LP2985IM5X-6.1/NOPB, this means ≥6.675 V under worst-case conditions.

Can LP2985IM5X-6.1/NOPB operate with a 2.2 µF ceramic output capacitor only, without additional bulk capacitance?

Yes. The LP2985IM5X-6.1/NOPB is explicitly designed to be stable with a single 2.2 µF ceramic output capacitor having ESR ≥5 mΩ - no additional bulk capacitance is required. This is confirmed in the datasheet's "Enhanced Stability" section and Typical Application schematic. Increasing capacitance beyond 2.2 µF is permitted and may improve transient response, but is not necessary for stability. Using lower-ESR ceramics (e.g., X7R, X5R) ensures compliance across temperature and bias conditions.

How does the BYPASS pin on LP2985IM5X-6.1/NOPB reduce output noise, and what capacitor value is recommended?

The BYPASS pin connects directly to the internal bandgap reference node. Adding a 10-nF ceramic capacitor between BYPASS and GND filters high-frequency reference noise, reducing total output noise from ~75 µV_RMS to 30 µV_RMS (300 Hz–50 kHz bandwidth). The datasheet specifies 10 nF as optimal; values between 1 nF and 100 nF are acceptable, but deviation reduces noise suppression efficacy. Use C0G/NP0 dielectric for lowest leakage and temperature drift - X7R is acceptable if size-constrained.

Is LP2985IM5X-6.1/NOPB compatible with tantalum or polymer capacitors on the output?

No - the LP2985IM5X-6.1/NOPB is characterized and guaranteed stable only with ceramic output capacitors having ESR ≥5 mΩ. Tantalum and polymer capacitors exhibit higher ESR and different phase characteristics that can destabilize the control loop, potentially causing oscillation or poor transient response. The datasheet explicitly states "The LP2985-N is designed specifically to work with ceramic output capacitors" and warns against using alternatives unless validated per application note SNVA032. For LP2985IM5X-6.1/NOPB, ceramic is mandatory.

What happens to LP2985IM5X-6.1/NOPB when the ON/OFF pin is left floating?

The ON/OFF pin has no internal pull-up or pull-down; leaving it floating risks undefined behavior due to noise coupling or leakage currents. The datasheet mandates active termination: tie to VIN if shutdown control is unused, or drive with a clean logic signal. Floating may cause intermittent enable/disable cycling, leading to unstable output voltage, excessive ground current, or thermal stress. For reliable operation, LP2985IM5X-6.1/NOPB requires ON/OFF to be either pulled high (>1.6 V) or low (<0.15 V) with ≤10 kΩ impedance - never left open.