Texas Instruments LP3985IM5-3.0

Overview

LP3985IM5-3.0 from Texas Instruments is a fixed-output, micropower, ultra-low-dropout CMOS voltage regulator delivering 150 mA at 3.0 V with ≤100 mV dropout at full load, 30 µVRMS output noise (10 Hz–100 kHz), and 50 dB PSRR at 1 kHz - optimized for RF power amplifier biasing and low-noise analog supply in cellular handsets.

For engineers reviewing the LP3985IM5-3.0 datasheet, LP3985IM5-3.0 pinout, LP3985IM5-3.0 application, or LP3985IM5-3.0 equivalent, key selection criteria include verified 3.0-V output tolerance (±3%), shutdown current ≤1.5 µA, fast 200 µs turn-on time with bypass capacitor precharge, and DSBGA package compatibility with space-constrained portable PCB layouts.

Technical Context

The LP3985IM5-3.0 implements a CMOS-based LDO architecture with internal 1.23-V bandgap reference, active bypass capacitor precharge circuit (70 µA current source), and thermal shutdown (160°C) plus short-circuit protection (600 mA steady-state limit). Its low ground current (85 µA at no load, 140 µA at 150 mA) sustains battery life in standby modes.

Operation requires VIN ≥ 3.3 V (VOUT + 0.3 V minimum), supports logic-controlled enable (VIH = 1.4 V, VIL = 0.4 V), and remains stable with 1-µF ±30% ceramic output capacitors - eliminating need for high-ESR tantalum types while enabling sub-2 mm × 2.5 mm total footprint in DSBGA.

Key Specifications

Pinout & Package

LP3985IM5-3.0 is packaged in a 5-pin DSBGA (YZR) with 1.502 mm × 1.045 mm body size and bottom-side solder balls. Pin mapping follows JEDEC-standard DSBGA numbering (A1–C3 grid).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3985IM5-3.0, TPL720F30 offers higher current and lower dropout but sacrifices DSBGA miniaturization and adds output capacitance requirement, while MCP1700T-3002E/MB trades noise performance and feature set for lower unit cost and simplified 3-pin layout.

Availability

LP3985IM5-3.0 is available at Aetrix Electronics and suitable for CDMA/GSM handset design, portable audio codec reference supplies, Bluetooth SoC power management, and other applications requiring stable component supply with tight voltage accuracy and ultra-low noise.

Supply support for LP3985IM5-3.0 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 company specializing in analog and embedded processing technologies, with leadership in power management ICs for portable electronics.

The LP3985 product line was designed specifically for battery-powered wireless applications demanding ultra-low noise, micropower operation, and minimal PCB footprint - targeting cellular handsets, portable information appliances, and RF subsystems.

FAQ

What is the minimum input voltage required for LP3985IM5-3.0 to regulate at 3.0 V?

The LP3985IM5-3.0 requires VIN ≥ VOUT + 0.3 V (i.e., ≥3.3 V) for proper regulation. Below this threshold, output voltage drops linearly with input; the 100-mV dropout spec applies only above 3.3 V. This ensures stable 3.0-V output across the usable range of a single-cell Li-ion battery (3.4–4.2 V).

Can LP3985IM5-3.0 operate without the BYPASS capacitor?

Yes, LP3985IM5-3.0 functions without the BYPASS capacitor but with higher output noise (230 nV/√Hz spectral density vs. 30 µVRMS broadband). The BYPASS pin is optional: omitting it simplifies layout but increases RMS noise - acceptable for non-RF digital supplies, whereas RF PA biasing requires the 0.01-µF cap to achieve 30 µVRMS.

Is LP3985IM5-3.0 stable with a 0402-size 1-µF X7R ceramic capacitor?

Yes, LP3985IM5-3.0 is stable with 0402 1-µF X7R ceramics if DC-bias derating is accounted for: at 3.0 V bias, typical 0402 X7R retains ≥0.7 µF (70% of nominal), meeting the 0.7–4.7 µF recommended range. Verify manufacturer's DC-bias curve - some 0402 parts fall below 0.7 µF at 3.0 V and require 0603 sizing.

What happens to LP3985IM5-3.0 during thermal overload?

When junction temperature reaches 160°C, LP3985IM5-3.0 activates thermal shutdown, disabling the output until temperature falls by 20°C (hysteresis). During shutdown, quiescent current remains ≤1.5 µA. This protects the device during sustained overload or poor PCB thermal design while allowing automatic recovery without system reset.

Does LP3985IM5-3.0 support reverse current blocking?

No, LP3985IM5-3.0 does not include reverse current blocking. If VIN falls below VOUT while enabled, reverse current can flow from OUT to IN through the pass transistor. For applications requiring backflow prevention (e.g., OR-ing configurations), an external Schottky diode or dedicated ideal diode controller must be added in series with the IN pin.