LM3671MFX-1.2 Equivalent & Substitute Parts

Part Overview

The LM3671MFX-1.2 is a buck switching regulator IC from Texas Instruments, delivering a fixed 1.2V output at 600mA. It operates across a 2.7V to 5.5V input range with a 2MHz switching frequency and integrated synchronous rectification. The part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. Active alternatives from Texas Instruments, Analog Devices, Microchip Technology, and Semtech Corporation provide direct functional replacement with enhanced product status and compliance certifications.

Substiute Parts

LM3671MFX-1.2

Texas InstrumentsIn Stock: 17207LM3671MFX-1.2 Datasheet

Current PartRFQ

LM3671MFX-1.2/NOPB

Texas InstrumentsIn Stock: 16135LM3671MFX-1.2/NOPB Datasheet

DirectRFQ

LM3674MF-1.2/NOPB

Texas InstrumentsIn Stock: 1147LM3674MF-1.2/NOPB Datasheet

DirectRFQ

LM3674MFX-1.2/NOPB

Texas InstrumentsIn Stock: 4445LM3674MFX-1.2/NOPB Datasheet

DirectRFQ

ADP2108AUJZ-1.2-R7

Analog Devices Inc.In Stock: 18099ADP2108AUJZ-1.2-R7 Datasheet

MFR RecommendedRFQ

MCP1603T-120I/OS

Microchip TechnologyIn Stock: 4498MCP1603T-120I/OS Datasheet

MFR RecommendedRFQ

SC4626CSKTRT

Semtech CorporationIn Stock: 9297SC4626CSKTRT Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

• Output voltage: 1.2V fixed
• Output current capability: minimum 600mA (or higher)
• Input voltage range: 2.7V to 5.5V minimum
• Package type: SOT-23-5 or equivalent footprint
• Topology: Buck switching regulator with synchronous rectification
• Switching frequency: 2MHz nominal (±20% tolerance acceptable)

Substitute parts are grouped into three categories:

Direct Equivalents (Texas Instruments): LM3671MFX-1.2/NOPB and LM3674 series variants maintain identical electrical specifications with improved product status and RoHS3 compliance.

Manufacturer-Recommended Alternatives: ADP2108AUJZ-1.2-R7 (Analog Devices) and MCP1603T-120I/OS (Microchip) provide equivalent functionality with enhanced operating temperature ranges and higher switching frequencies.

Extended Capability Option: SC4626CSKTRT (Semtech) offers increased output current (1A) with compatible input/output voltage specifications, suitable for applications requiring higher current delivery.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Preferred): LM3671MFX-1.2/NOPB is the primary substitute, offering identical electrical specifications with active product status and RoHS3 compliance. This part maintains full compatibility with existing designs without circuit modification.

For Enhanced Reliability: LM3674MFX-1.2/NOPB provides the same performance with active status and RoHS3 compliance. The LM3674 series is recommended for new designs requiring long-term supply assurance.

For Extended Temperature Range: ADP2108AUJZ-1.2-R7 (Analog Devices) and MCP1603T-120I/OS (Microchip) support operating temperatures to 125°C, suitable for industrial and automotive applications. ADP2108AUJZ-1.2-R7 offers lower minimum input voltage (2.3V) and higher switching frequency (3MHz). MCP1603T-120I/OS delivers 500mA output current, acceptable for applications with reduced current requirements.

For Higher Current Delivery: SC4626CSKTRT (Semtech) provides 1A output current with compatible voltage specifications. This part is classified as "Not For New Designs" and should be used only for legacy system support or when higher current capacity is essential.

Compliance Consideration: All active substitute parts meet RoHS3 compliance, addressing the non-compliant status of the original LM3671MFX-1.2. For new production, select from LM3671MFX-1.2/NOPB, LM3674MFX-1.2/NOPB, ADP2108AUJZ-1.2-R7, or MCP1603T-120I/OS.

Frequently Asked Questions (FAQ)

Q: Can LM3671MFX-1.2/NOPB be used as a direct drop-in replacement?

A: Yes. LM3671MFX-1.2/NOPB is electrically and mechanically identical to LM3671MFX-1.2, with the same output voltage (1.2V), current rating (600mA), input range (2.7V–5.5V), switching frequency (2MHz), and SOT-23-5 package. No circuit modifications are required.

Q: What is the difference between LM3674MF-1.2/NOPB and LM3674MFX-1.2/NOPB?

A: Both deliver identical electrical performance. LM3674MF-1.2/NOPB is supplied in Cut Tape (CT) & Digi-Reel packaging, while LM3674MFX-1.2/NOPB is supplied in Tape & Reel (TR) packaging. Selection depends on procurement and assembly requirements.

Q: Why does MCP1603T-120I/OS have lower output current (500mA vs. 600mA)?

A: MCP1603T-120I/OS is rated for 500mA maximum output current. It is suitable for applications requiring up to 500mA. For designs requiring the full 600mA specification, use LM3671MFX-1.2/NOPB, LM3674 variants, or ADP2108AUJZ-1.2-R7.

Q: Can ADP2108AUJZ-1.2-R7 operate at lower input voltages than the original part?

A: Yes. ADP2108AUJZ-1.2-R7 supports a minimum input voltage of 2.3V, compared to 2.7V for LM3671MFX-1.2. This provides additional design flexibility for low-voltage applications.

Q: Is SC4626CSKTRT recommended for new designs?

A: No. SC4626CSKTRT is classified as "Not For New Designs." It is available for legacy system support and applications where 1A output current is required. For new designs, select LM3671MFX-1.2/NOPB, LM3674MFX-1.2/NOPB, ADP2108AUJZ-1.2-R7, or MCP1603T-120I/OS.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts (LM3671MFX-1.2/NOPB, LM3674 variants, ADP2108AUJZ-1.2-R7, MCP1603T-120I/OS) are RoHS3 compliant. SC4626CSKTRT is RoHS compliant. The original LM3671MFX-1.2 is RoHS non-compliant.

Q: What is the impact of higher switching frequency in ADP2108AUJZ-1.2-R7 (3MHz vs. 2MHz)?

A: Higher switching frequency (3MHz) allows for smaller external filter components and potentially improved transient response. Circuit design may require adjustment of compensation networks. Thermal performance may differ due to increased switching losses.

Q: Can these parts be used interchangeably in the same PCB layout?

A: Yes, all substitute parts use the SOT-23-5 or TSOT-23-5 package with identical pinout and footprint compatibility. PCB layout modifications are not required for package-level substitution.