LP3990SD-2.8/NOPB Equivalent & Substitute Parts

Part Overview

The LP3990SD-2.8/NOPB is a linear voltage regulator IC manufactured by Texas Instruments, designed to deliver a fixed 2.8V output at 150mA. This device operates as a positive fixed regulator with integrated enable control and protection features including over-temperature and short-circuit protection. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The LP3990SD-2.8/NOPB is packaged in a 6-WSON (3x3) form factor suitable for surface mount applications across industrial and consumer electronics.

Substiute Parts

LP3990SD-2.8/NOPB

Texas InstrumentsIn Stock: 1015LP3990SD-2.8/NOPB Datasheet

Current PartRFQ

LP3990MF-2.8/NOPB

Texas InstrumentsIn Stock: 6372LP3990MF-2.8/NOPB Datasheet

MFR RecommendedRFQ

LP5900SD-2.8/NOPB

Texas InstrumentsIn Stock: 21874LP5900SD-2.8/NOPB Datasheet

Parametric EquivalentRFQ

LP5900SDX-2.8/NOPB

Texas InstrumentsIn Stock: 5929LP5900SDX-2.8/NOPB Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the LP3990SD-2.8/NOPB is determined by the following critical parameters: fixed output voltage of 2.8V, output current capability of 150mA, maximum input voltage of 6V or lower, voltage dropout characteristics, quiescent current specifications, operating temperature range of -40°C to 85°C, and regulatory compliance (ROHS3).

Two categories of substitutes are identified:

MFR Recommended Substitute (Package Change): LP3990MF-2.8/NOPB maintains identical electrical specifications but changes the package from 6-WSON (3x3) to SOT-23-5, allowing for different PCB layout requirements while preserving all functional parameters.

Parametric Equivalents (Same Package Family): LP5900SD-2.8/NOPB and LP5900SDX-2.8/NOPB are functionally equivalent with improved performance characteristics. Both maintain the 6-WSON package family (2.2x2.5 variant), 2.8V fixed output, 150mA current capability, and -40°C to 85°C operating range. These parts offer lower dropout voltage (0.15V vs 0.2V), reduced quiescent current (50 µA vs 80 µA), and superior PSRR performance (85dB ~ 40dB vs 55dB ~ 35dB), with active product status ensuring long-term availability.

Parameter Comparison

Engineering Selection Recommendations

For applications currently using the obsolete LP3990SD-2.8/NOPB, the following selection criteria apply:

Package Compatibility Requirement: If the existing PCB layout uses the 6-WSON (3x3) footprint and cannot be modified, LP5900SD-2.8/NOPB or LP5900SDX-2.8/NOPB are direct mechanical and electrical substitutes. Both are active products with superior electrical performance and identical pinout compatibility within the 6-WSON package family.

Alternative Package Requirement: If PCB redesign is acceptable and SOT-23-5 footprint is preferred for space or manufacturing considerations, LP3990MF-2.8/NOPB maintains identical electrical specifications to the original part while offering active product status and improved supply availability.

Performance Enhancement Option: LP5900SD-2.8/NOPB and LP5900SDX-2.8/NOPB provide measurable performance improvements including 25% lower dropout voltage, 37.5% reduction in quiescent current, and superior power supply rejection ratio across a wider frequency range. These improvements reduce thermal dissipation and improve output voltage stability, particularly beneficial in noise-sensitive applications.

All substitute parts maintain ROHS3 compliance, identical operating temperature range, and equivalent protection features, ensuring regulatory and functional compatibility with the original design.

Frequently Asked Questions (FAQ)

Q: Can LP3990MF-2.8/NOPB be used as a direct replacement for LP3990SD-2.8/NOPB?

A: LP3990MF-2.8/NOPB is electrically equivalent with identical output voltage, current rating, and protection features. However, the package changes from 6-WSON (3x3) to SOT-23-5, requiring PCB layout modification. Pin configuration differs between packages, necessitating schematic and layout redesign.

Q: What is the primary advantage of LP5900SD-2.8/NOPB over the original LP3990SD-2.8/NOPB?

A: LP5900SD-2.8/NOPB delivers superior performance with 25% lower dropout voltage (0.15V vs 0.2V), 37.5% lower quiescent current (50 µA vs 80 µA), and significantly improved PSRR (85dB ~ 40dB vs 55dB ~ 35dB). The part maintains the same 6-WSON package family and is an active product with guaranteed long-term availability.

Q: Are LP5900SD-2.8/NOPB and LP5900SDX-2.8/NOPB interchangeable?

A: Yes. Both parts are parametrically identical with the same electrical specifications, output voltage, current rating, and operating temperature range. The primary difference is packaging designation; both use 6-WSON (2.2x2.5) form factor and are suitable for identical applications.

Q: What is the maximum input voltage for LP5900 series parts compared to LP3990SD-2.8/NOPB?

A: LP3990SD-2.8/NOPB supports maximum input voltage of 6V, while LP5900SD-2.8/NOPB and LP5900SDX-2.8/NOPB support 5.5V maximum. Applications requiring input voltages between 5.5V and 6V must use LP3990MF-2.8/NOPB or remain with the original LP3990SD-2.8/NOPB if available.

Q: Do all substitute parts maintain the same control and protection features?

A: Yes. All substitute parts include enable control functionality and identical protection features: over-temperature and short-circuit protection. Operating temperature range remains -40°C to 85°C across all variants.

Q: Is PCB layout modification required when switching from LP3990SD-2.8/NOPB to LP5900SD-2.8/NOPB?

A: No PCB layout modification is required. Both parts use the 6-WSON package family with identical pinout and footprint compatibility. The LP5900SD-2.8/NOPB uses a smaller die size (2.2x2.5 vs 3x3) but maintains the same external dimensions and pin configuration.