LP3961EMPX-1.8 Linear Voltage Regulator — Equivalent & Substitute Parts

Part Overview

The LP3961EMPX-1.8 is a linear voltage regulator IC from Texas Instruments, classified as a positive fixed output 1.8V power management device with 800mA output capability in SOT-223-5 surface mount packaging. This part is currently listed as obsolete, making identification of equivalent and substitute parts essential for design continuity and procurement planning. Active alternatives with identical or compatible electrical and mechanical specifications are available from both Texas Instruments and National Semiconductor product lines.

Substiute Parts

LP3961EMPX-1.8

Texas InstrumentsIn Stock: 17333LP3961EMPX-1.8 Datasheet

Current PartRFQ

LP3961EMPX-1.8/NOPB

Texas InstrumentsIn Stock: 821LP3961EMPX-1.8/NOPB Datasheet

DirectRFQ

LP3871EMP-1.8/NOPB

National SemiconductorIn Stock: 3603LP3871EMP-1.8/NOPB Datasheet

Parametric EquivalentRFQ

LP3874EMP-1.8/NOPB

National SemiconductorIn Stock: 3337LP3874EMP-1.8/NOPB Datasheet

Parametric EquivalentRFQ

LP3874EMPX-1.8/NOPB

Texas InstrumentsIn Stock: 4235LP3874EMPX-1.8/NOPB Datasheet

Parametric EquivalentRFQ

LP3961EMP-1.8/NOPB

National SemiconductorIn Stock: 2885LP3961EMP-1.8/NOPB Datasheet

Parametric EquivalentRFQ

LP3964EMP-1.8/NOPB

Texas InstrumentsIn Stock: 1375LP3964EMP-1.8/NOPB Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LP3961EMPX-1.8 is determined by strict equivalence across the following electrical and mechanical parameters:

• Fixed output voltage of 1.8V
• Output current rating of 800mA
• Maximum input voltage of 7V
• Voltage dropout specification of 0.35V @ 800mA
• Operating temperature range of -40°C to 125°C
• Surface mount packaging in SOT-223-5 or compatible TO-261-5/TO-261AB case
• Enable control feature
• Over current, over temperature, and short circuit protection

Substitute parts are grouped into two categories: direct manufacturer equivalents (same part number with packaging variants) and parametric equivalents (different part numbers with identical electrical specifications and compatible packaging).

Parameter Comparison

Engineering Selection Recommendations

For applications currently using the obsolete LP3961EMPX-1.8, the following selection criteria apply:

Primary Recommendation: LP3961EMPX-1.8/NOPB (Texas Instruments) — Direct equivalent with identical part number, active product status, ROHS3 compliance, and tape & reel packaging. This part maintains full electrical and mechanical compatibility with the original design.

Alternative Selections:

LP3874EMPX-1.8/NOPB (Texas Instruments) — Active product with ROHS3 compliance, SOT-223-5 packaging, and identical electrical specifications. Suitable for new designs or redesigns requiring RoHS compliance.

LP3964EMP-1.8/NOPB (Texas Instruments) — Active product with ROHS3 compliance and SOT-223-5 packaging. Maintains electrical equivalence with the original part.

LP3871EMP-1.8/NOPB (National Semiconductor) — Active product with lower quiescent current (5 mA vs. 9 mA), SOT-223 packaging. Suitable where reduced standby power consumption is beneficial. Verify package compatibility with existing PCB layouts.

LP3874EMP-1.8/NOPB (National Semiconductor) — Active product with SOT-223 packaging and identical quiescent current specification. Verify package compatibility with existing PCB layouts.

LP3961EMP-1.8/NOPB (National Semiconductor) — Active product with SOT-223 packaging and identical electrical specifications. Verify package compatibility with existing PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can I directly replace LP3961EMPX-1.8 with LP3961EMPX-1.8/NOPB?

A: Yes. LP3961EMPX-1.8/NOPB is the direct equivalent with identical electrical specifications, same SOT-223-5 packaging, and active product status. The /NOPB suffix indicates lead-free and halogen-free compliance.

Q: What is the difference between SOT-223-5 and SOT-223 packaging?

A: SOT-223-5 is a 5-pin variant of the SOT-223 package. Parts specified for SOT-223-5 (such as LP3961EMPX-1.8/NOPB and LP3874EMPX-1.8/NOPB) have identical pin configurations and footprints. Parts specified for SOT-223 (such as LP3871EMP-1.8/NOPB) may have different pin assignments. Verify PCB layout compatibility before substitution.

Q: Why do some substitute parts have lower quiescent current?

A: LP3871EMP-1.8/NOPB specifies 5 mA quiescent current compared to 9 mA for the original part. This represents a design improvement in the LP3871 series. Both values meet the electrical requirements for 1.8V 800mA regulation and are functionally equivalent for this application.

Q: Are all substitute parts RoHS compliant?

A: LP3961EMPX-1.8/NOPB, LP3874EMPX-1.8/NOPB, and LP3964EMP-1.8/NOPB are ROHS3 compliant. LP3871EMP-1.8/NOPB, LP3874EMP-1.8/NOPB, and LP3961EMP-1.8/NOPB do not specify RoHS status in the provided data. Verify RoHS compliance requirements for your application before selection.

Q: Can I use National Semiconductor parts as direct replacements?

A: National Semiconductor parts (LP3871EMP-1.8/NOPB, LP3874EMP-1.8/NOPB, LP3961EMP-1.8/NOPB) meet all electrical specifications but use SOT-223 packaging instead of SOT-223-5. Verify that your PCB layout accommodates SOT-223 pin configuration and footprint before substitution.

Q: What inventory levels are available for each substitute?

A: LP3961EMPX-1.8/NOPB: 762 Pcs; LP3871EMP-1.8/NOPB: 3550 Pcs; LP3874EMP-1.8/NOPB: 3294 Pcs; LP3874EMPX-1.8/NOPB: 4200 Pcs; LP3961EMP-1.8/NOPB: 2836 Pcs; LP3964EMP-1.8/NOPB: 1267 Pcs.