LP3961EMP-1.8 Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The LP3961EMP-1.8 is a linear voltage regulator IC from Texas Instruments, classified as a Power Management (PMIC) component. This device delivers a fixed 1.8V output at 800mA in a SOT-223-5 surface mount package. The main part is currently listed as obsolete, making equivalent substitute parts essential for ongoing design support and production continuity. Identifying compatible alternatives ensures system reliability while maintaining electrical and mechanical compatibility.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	1.8V
Output Current	800mA
Input Voltage (Max)	7V
Voltage Dropout (Max)	0.35V @ 800mA
Quiescent Current (Iq)	9 mA
Output Configuration	Positive Fixed
Package Type	SOT-223-5 (TO-261-5, TO-261AB)
Operating Temperature Range	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Short Circuit
Control Features	Enable

Substitute Part Grouping Explanation

Substitute parts for the LP3961EMP-1.8 are qualified based on strict electrical and mechanical parameter matching:

Critical Matching Parameters:

Fixed output voltage of 1.8V
Output current rating of 800mA
Maximum input voltage of 7V
Voltage dropout of 0.35V @ 800mA
SOT-223-5 package compatibility (TO-261-5, TO-261AB)
Operating temperature range of -40°C to 125°C
Enable control feature
Over Current, Over Temperature, and Short Circuit protection

All substitute parts listed maintain these core electrical specifications and package requirements, ensuring direct functional equivalence in circuit applications.

Parameter Comparison

Part Number	Manufacturer	Status	Output Voltage	Output Current	Dropout (Max)	Iq (mA)	Package	Inventory (Pcs)
LP3961EMP-1.8	Texas Instruments	Obsolete	1.8V	800mA	0.35V @ 800mA	9	SOT-223-5	20400
LP3871EMP-1.8/NOPB	National Semiconductor	Active	1.8V	800mA	0.35V @ 800mA	5	SOT-223	3550
LP3874EMP-1.8/NOPB	National Semiconductor	Active	1.8V	800mA	0.35V @ 800mA	9	SOT-223	3294
LP3874EMPX-1.8/NOPB	Texas Instruments	Active	1.8V	800mA	0.35V @ 800mA	9	SOT-223-5	4200
LP3961EMP-1.8/NOPB	National Semiconductor	Active	1.8V	800mA	0.35V @ 800mA	9	SOT-223	2836
LP3961EMPX-1.8/NOPB	Texas Instruments	Active	1.8V	800mA	0.35V @ 800mA	9	SOT-223-5	762
LP3964EMP-1.8/NOPB	Texas Instruments	Active	1.8V	800mA	0.35V @ 800mA	9	SOT-223-5	1267

Engineering Selection Recommendations

Primary Recommendation: LP3874EMPX-1.8/NOPB (Texas Instruments)

Active product status ensures long-term availability and support
ROHS3 compliant, meeting current regulatory requirements
SOT-223-5 package matches the original LP3961EMP-1.8 pinout exactly
Adequate inventory (4200 Pcs) for production continuity
Identical electrical specifications including 9 mA quiescent current

Secondary Recommendation: LP3961EMPX-1.8/NOPB (Texas Instruments)

Active product status with ROHS3 compliance
Maintains SOT-223-5 package compatibility
Identical electrical performance to the original part
Lower inventory availability (762 Pcs) may require lead time planning

Alternative Options: LP3964EMP-1.8/NOPB (Texas Instruments)

Active status with ROHS3 compliance
SOT-223-5 package compatibility
Equivalent electrical specifications
Moderate inventory (1267 Pcs)

National Semiconductor Options: LP3871EMP-1.8/NOPB and LP3874EMP-1.8/NOPB

Both active products with equivalent electrical performance
SOT-223 package (minor variant from SOT-223-5)
Suitable for applications where package variant compatibility is confirmed
LP3871EMP-1.8/NOPB offers lower quiescent current (5 mA vs 9 mA)

Frequently Asked Questions (FAQ)

Q: Can I use LP3871EMP-1.8/NOPB as a direct replacement for LP3961EMP-1.8? A: Yes, electrically. The LP3871EMP-1.8/NOPB meets all core electrical specifications (1.8V output, 800mA current, 0.35V dropout). However, it uses SOT-223 packaging versus the original SOT-223-5. Verify PCB footprint compatibility before substitution.

Q: What is the difference between SOT-223 and SOT-223-5 packages? A: Both are surface mount packages with similar pinouts. SOT-223-5 is a 5-pin variant, while SOT-223 is the standard 3-pin configuration. Confirm your PCB design supports the specific package variant before selection.

Q: Why is the original LP3961EMP-1.8 listed as obsolete? A: Obsolete status indicates the manufacturer has discontinued production. Active substitute parts with identical specifications are available to ensure design continuity and production support.

Q: Does quiescent current difference matter between LP3871EMP-1.8/NOPB (5 mA) and other options (9 mA)? A: Quiescent current affects standby power consumption. The 4 mA difference is significant only in battery-powered or ultra-low-power applications. For standard applications, both are functionally equivalent.

Q: Are all substitute parts RoHS compliant? A: The active substitute parts (LP3874EMPX-1.8/NOPB, LP3961EMPX-1.8/NOPB, LP3964EMP-1.8/NOPB) are ROHS3 compliant. National Semiconductor variants do not specify RoHS status in the provided data.

Q: Which substitute has the best inventory availability? A: LP3874EMPX-1.8/NOPB offers the highest inventory (4200 Pcs) among active substitutes with SOT-223-5 package compatibility and ROHS3 compliance.

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