LM3671MFX-2.8 Equivalent & Substitute Parts

Part Overview

The LM3671MFX-2.8 is a buck switching regulator IC from Texas Instruments, designed for positive fixed 2.8V output applications with 600mA current capacity. This component operates as a step-down converter with a single output configuration and synchronous rectification capability. The main part number is currently listed as obsolete, which necessitates identification of active equivalent alternatives for new designs and production continuity. Substitute parts maintain identical electrical specifications and package form factors while offering current product status and updated compliance certifications.

Key Parameters

Parameter	Value
Function	Step-Down (Buck)
Output Configuration	Positive
Output Type	Fixed
Number of Outputs	1
Voltage - Input (Min)	2.7V
Voltage - Input (Max)	5.5V
Voltage - Output (Fixed)	2.8V
Current - Output	600mA
Frequency - Switching	2MHz
Synchronous Rectifier	Yes
Operating Temperature Range	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Package / Case	SC-74A, SOT-753
Supplier Device Package	SOT-23-5
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the LM3671MFX-2.8 is determined by strict equivalence across the following critical parameters:

Input voltage range (2.7V to 5.5V), fixed output voltage (2.8V), output current capacity (600mA), switching frequency (2MHz), synchronous rectification capability, and package form factor (SOT-23-5 / SC-74A). All substitute parts must maintain identical electrical performance characteristics and physical packaging to ensure direct replacement without circuit redesign.

The identified substitute parts are LM3671MFX-2.8/NOPB and LM3674MF-2.8/NOPB, both from Texas Instruments. These parts satisfy all electrical and mechanical compatibility requirements. The primary distinction between candidates lies in product status (active vs. obsolete) and regulatory compliance certifications.

Parameter Comparison

Parameter	LM3671MFX-2.8	LM3671MFX-2.8/NOPB	LM3674MF-2.8/NOPB
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active
Function	Step-Down	Step-Down	Step-Down
Output Configuration	Positive	Positive	Positive
Output Type	Fixed	Fixed	Fixed
Number of Outputs	1	1	1
Voltage - Input (Min)	2.7V	2.7V	2.7V
Voltage - Input (Max)	5.5V	5.5V	5.5V
Voltage - Output (Fixed)	2.8V	2.8V	2.8V
Current - Output	600mA	600mA	600mA
Frequency - Switching	2MHz	2MHz	2MHz
Synchronous Rectifier	Yes	Yes	Yes
Operating Temperature (Min)	-40°C	-40°C	-30°C
Operating Temperature (Max)	85°C	85°C	85°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	SC-74A, SOT-753	SC-74A, SOT-753	SC-74A, SOT-753
Supplier Device Package	SOT-23-5	SOT-23-5	SOT-23-5
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected
ECCN	EAR99	EAR99	EAR99

Engineering Selection Recommendations

For new designs and production applications, LM3671MFX-2.8/NOPB is the primary recommended substitute. This part maintains identical electrical specifications and package configuration to the obsolete LM3671MFX-2.8 while offering active product status and ROHS3 compliance certification. The /NOPB designation indicates lead-free plating, aligning with current manufacturing standards.

LM3674MF-2.8/NOPB serves as a secondary alternative with equivalent electrical performance and active status. The operating temperature minimum specification differs at -30°C versus -40°C for the primary substitute. This temperature range variance must be evaluated against application requirements. Both substitute parts carry ROHS3 compliance and REACH unaffected status, providing regulatory alignment for modern supply chains.

Frequently Asked Questions (FAQ)

Q: Can LM3671MFX-2.8/NOPB directly replace the obsolete LM3671MFX-2.8 without circuit modification?

A: Yes. Both parts share identical electrical specifications (2.8V fixed output, 600mA current, 2MHz switching frequency, 2.7V to 5.5V input range) and package form factor (SOT-23-5). Direct PCB substitution is supported without design changes.

Q: What is the difference between LM3671MFX-2.8/NOPB and LM3674MF-2.8/NOPB?

A: Both parts deliver equivalent electrical performance and packaging. The primary distinction is the minimum operating temperature: LM3671MFX-2.8/NOPB operates from -40°C, while LM3674MF-2.8/NOPB operates from -30°C. Select based on application temperature requirements.

Q: Why is the original LM3671MFX-2.8 marked as obsolete?

A: The original part number lacks the /NOPB suffix and does not carry ROHS3 compliance certification. Texas Instruments transitioned to the /NOPB variant to meet current regulatory requirements and manufacturing standards.

Q: Are there any package or pinout differences between these parts?

A: No. All three part numbers use the SC-74A / SOT-753 package with SOT-23-5 supplier device package designation. Pinout and physical dimensions are identical.

Q: What does the /NOPB designation mean?

A: /NOPB indicates "No Plumbum" (lead-free) plating, confirming compliance with RoHS directives and modern environmental standards.

Q: Can I use LM3674MF-2.8/NOPB in applications requiring -40°C operation?

A: No. LM3674MF-2.8/NOPB is specified only to -30°C minimum. For applications requiring -40°C operation, use LM3671MFX-2.8/NOPB.

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