LM3671MF-1.8 Equivalent & Substitute Parts

Part Overview

The LM3671MF-1.8 is a buck switching regulator IC from Texas Instruments, delivering a fixed 1.8V output at 600mA with input voltage range of 2.7V to 5.5V. This component is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The part operates across -40°C to 85°C and features synchronous rectification in a compact SC-74A (SOT-753) surface mount package.

Substiute Parts

LM3671MF-1.8

Texas InstrumentsIn Stock: 16711LM3671MF-1.8 Datasheet

Current PartRFQ

LM3671MF-1.8/NOPB

Texas InstrumentsIn Stock: 8755LM3671MF-1.8/NOPB Datasheet

DirectRFQ

LM3674MF-1.8/NOPB

Texas InstrumentsIn Stock: 2914LM3674MF-1.8/NOPB Datasheet

DirectRFQ

LM3674MFX-1.8/NOPB

Texas InstrumentsIn Stock: 1168LM3674MFX-1.8/NOPB Datasheet

DirectRFQ

MAX1734EUK18+T

Analog Devices Inc./Maxim IntegratedIn Stock: 12414MAX1734EUK18+T Datasheet

MFR RecommendedRFQ

MCP1603T-180I/OS

Microchip TechnologyIn Stock: 15651MCP1603T-180I/OS Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the LM3671MF-1.8 is determined by the following critical parameters:

• Output voltage: 1.8V fixed
• Input voltage range: 2.7V to 5.5V
• Output current capability: minimum 500mA (preferred) to 600mA
• Topology: Buck switching regulator
• Synchronous rectification: required
• Package: SC-74A or SOT-753 compatible footprint
• Switching frequency: 2MHz nominal
• Operating temperature range: -40°C minimum to 85°C minimum

Substitute parts are grouped into two categories: direct equivalents (identical electrical specifications and active product status) and functional alternatives (compatible electrical performance with minor parameter variations).

Parameter Comparison

Engineering Selection Recommendations

Direct Equivalents (Preferred for Replacement)

LM3671MF-1.8/NOPB, LM3674MF-1.8/NOPB, and LM3674MFX-1.8/NOPB are all active products from Texas Instruments with identical electrical specifications to the obsolete LM3671MF-1.8. All three are ROHS3 compliant and maintain the same 1.8V output, 600mA current capability, 2.7V to 5.5V input range, and 2MHz switching frequency. The primary difference is packaging format: LM3671MF-1.8/NOPB is supplied in Cut Tape (CT) & Digi-Reel format, while LM3674MF-1.8/NOPB and LM3674MFX-1.8/NOPB are supplied in Tape & Reel (TR) format. LM3674MF-1.8/NOPB and LM3674MFX-1.8/NOPB have a minimum operating temperature of -30°C versus -40°C for the original part.

Functional Alternatives (For Current-Limited Applications)

MAX1734EUK18+T from Analog Devices Inc./Maxim Integrated is an active product with identical input voltage range, output voltage, and package compatibility. However, output current is limited to 250mA, making this suitable only for applications requiring less than 250mA. Switching frequency is 1.2MHz. This part is ROHS3 compliant and operates across -40°C to 85°C.

MCP1603T-180I/OS from Microchip Technology is an active product with 500mA output current capability, meeting most load requirements below 600mA. Input voltage range and output voltage match the original part. Switching frequency is 2MHz. This part is ROHS3 compliant and operates across -40°C to 125°C (junction temperature). Package is SOT-23-5 Thin (TSOT-23-5), which is footprint-compatible with SC-74A but may require PCB layout verification for thermal performance.

Frequently Asked Questions (FAQ)

Q: Can I use LM3674MF-1.8/NOPB as a direct replacement for LM3671MF-1.8?

A: Yes. Both parts deliver 1.8V at 600mA with 2.7V to 5.5V input range, 2MHz switching frequency, and synchronous rectification in the same SC-74A package. LM3674MF-1.8/NOPB is active and ROHS3 compliant. The minimum operating temperature is -30°C instead of -40°C; verify this meets your application requirements.

Q: What is the difference between LM3671MF-1.8/NOPB and LM3674MFX-1.8/NOPB?

A: Both are electrically identical with 600mA output current and identical electrical specifications. The difference is in packaging format and supplier designation. LM3671MF-1.8/NOPB is supplied in Cut Tape & Digi-Reel format, while LM3674MFX-1.8/NOPB is supplied in Tape & Reel format. Select based on your procurement and assembly requirements.

Q: Can MAX1734EUK18+T replace the LM3671MF-1.8 in all applications?

A: No. MAX1734EUK18+T is limited to 250mA output current, compared to 600mA for the original part. Use this substitute only for applications requiring 250mA or less. Switching frequency is also reduced to 1.2MHz.

Q: Is MCP1603T-180I/OS compatible with the original PCB layout?

A: MCP1603T-180I/OS uses SOT-23-5 Thin (TSOT-23-5) packaging, which is footprint-compatible with SC-74A. However, verify thermal performance and PCB layout compatibility, as the thin package may affect heat dissipation characteristics. Output current is 500mA, suitable for applications below 600mA.

Q: Are all substitute parts RoHS compliant?

A: Yes. All active substitute parts listed (LM3671MF-1.8/NOPB, LM3674MF-1.8/NOPB, LM3674MFX-1.8/NOPB, MAX1734EUK18+T, and MCP1603T-180I/OS) are ROHS3 compliant. The original LM3671MF-1.8 is RoHS non-compliant.

Q: What is the key difference in operating temperature between substitute parts?

A: LM3671MF-1.8/NOPB operates -40°C to 85°C (TA). LM3674MF-1.8/NOPB and LM3674MFX-1.8/NOPB operate -30°C to 85°C (TA). MAX1734EUK18+T operates -40°C to 85°C (TA). MCP1603T-180I/OS operates -40°C to 125°C (TJ). Select based on your minimum operating temperature requirement.