Texas Instruments LP3985IM5X-3.0

Overview

LP3985IM5X-3.0 from Texas Instruments is a micropower, ultra-low-noise, ultra-low-dropout CMOS voltage regulator delivering 150 mA at fixed 3.0 V output. It operates from 2.5 V to 6 V input, achieves ≤100 mV dropout at full load, consumes ≤1.5 µA in shutdown, and features a dedicated BYPASS pin for noise reduction. It is widely used in RF power amplifier biasing and low-noise analog supply rails in cellular handsets.

For engineers reviewing the LP3985IM5X-3.0 datasheet, LP3985IM5X-3.0 pinout, LP3985IM5X-3.0 application, or LP3985IM5X-3.0 equivalent, key selection criteria include its 30 µVRMS output noise (10 Hz–100 kHz), 50 dB PSRR at 1 kHz, DSBGA-5 package footprint (<1.6 mm²), logic-controlled enable functionality, and verified stability with 1-µF ceramic output capacitors.

Technical Context

The LP3985IM5X-3.0 uses a CMOS pass transistor architecture with internal bandgap reference (1.23 V) and fast-turnon pre-charge circuitry for the BYPASS capacitor. Its enable threshold is VIH = 1.4 V (min) and VIL = 0.4 V (max), supporting direct connection to GPIOs of baseband processors.

It integrates thermal shutdown (160°C trip, 20°C hysteresis) and short-circuit current limiting (600 mA steady-state). Ground current remains stable across load (85–140 µA at 0–150 mA), and dropout voltage is specified up to 100 mV at 150 mA - critical for Li-ion battery discharge down to 3.0 V while maintaining regulation.

Key Specifications

Pinout & Package

LP3985IM5X-3.0 is packaged in a 5-pin DSBGA (YZR) with body size 1.502 mm × 1.045 mm (MAX), optimized for ultra-compact portable PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F30PDBVR and MCP1700-3002E/TO, the LP3985IM5X-3.0 uniquely balances ultra-low noise (30 µVRMS), ultra-low dropout (≤100 mV), and DSBGA-5 miniaturization - making it optimal for space-constrained, battery-powered RF and audio subsystems where both efficiency and signal integrity are essential.

Availability

LP3985IM5X-3.0 is available at Aetrix Electronics and suitable for CDMA/GSM handset design, portable audio codec supply, Bluetooth baseband power management, and RF front-end biasing requiring stable component supply across production lifecycles.

Supply support for LP3985IM5X-3.0 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 specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and consumer applications.

The LP3985 family was designed specifically for portable wireless devices demanding ultra-low noise, ultra-low dropout, and micropower operation - targeting RF power amplifier bias, audio codec supplies, and other noise-sensitive analog rails in cellular handsets.

FAQ

What is the maximum input voltage rating for the LP3985IM5X-3.0?

The LP3985IM5X-3.0 has an absolute maximum input voltage of 6.5 V. However, its recommended operating range is 2.5 V to 6 V. Exceeding 6.5 V risks permanent damage per the Absolute Maximum Ratings table. For reliable long-term operation, VIN should remain within the recommended range, especially considering that dropout performance degrades near the upper limit due to internal headroom constraints.

Does the LP3985IM5X-3.0 require an external bypass capacitor to meet its 30 µVRMS noise specification?

Yes, the 30 µVRMS output noise specification for the LP3985IM5X-3.0 is measured with a 0.01-µF capacitor connected to the BYPASS pin. Without this capacitor, typical output noise rises to 230 nV/√Hz spectral density, resulting in significantly higher integrated RMS noise. The BYPASS capacitor is optional only if noise performance is not critical; omitting it forfeits the ultra-low-noise capability explicitly designed into the LP3985IM5X-3.0.

Can the LP3985IM5X-3.0 be used with a 1-µF X5R ceramic capacitor on the output?

Yes, the LP3985IM5X-3.0 is stable with 1-µF X5R ceramic capacitors, though X7R is preferred for wider temperature coverage (−55°C to 125°C vs. −55°C to 85°C for X5R). The datasheet confirms stability with ±30% tolerance ceramics, and X5R meets ESR requirements (5–500 mΩ). However, designers must verify DC-bias derating - a 1-µF X5R in 0402 case may drop below 0.7 µF at 3.0 V bias, risking instability.

What is the thermal shutdown behavior of the LP3985IM5X-3.0?

The LP3985IM5X-3.0 activates thermal shutdown at 160°C junction temperature and includes 20°C hysteresis, meaning it resumes normal operation only after cooling to ≤140°C. This protects against sustained overload or poor PCB thermal design. During shutdown, output is disabled and quiescent current remains ≤1.5 µA. The device does not latch off - it automatically recovers once temperature falls within safe limits, ensuring robustness in transient thermal events.

Is the LP3985IM5X-3.0 pin-compatible with other variants in the LP3985 family, such as LP3985IM5X-2.8?

Yes, all LP3985IM5X-x.x variants share identical DSBGA-5 pinout and package dimensions (1.502 mm × 1.045 mm), including LP3985IM5X-3.0, LP3985IM5X-2.8, and LP3985IM5X-3.3. Pin functions (IN, OUT, GND, EN, BYPASS) and physical layout are invariant across output voltage options. This allows drop-in replacement during design iteration or voltage tuning without PCB revision - provided the input voltage margin and load requirements remain compatible with the new output voltage.