LM3674MF-1.8 Equivalent & Substitute Parts

Part Overview

The LM3674MF-1.8 is a buck switching regulator IC from Texas Instruments designed for positive fixed 1.8V output applications with 600mA current capacity. This device operates across a 2.7V to 5.5V input range and integrates a synchronous rectifier for efficient power conversion. The part is currently classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements.

Substiute Parts

LM3674MF-1.8

Texas InstrumentsIn Stock: 4502LM3674MF-1.8 Datasheet

Current PartRFQ

LM3674MF-1.8/NOPB

Texas InstrumentsIn Stock: 2914LM3674MF-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

RT8009-18GB

Richtek USA Inc.In Stock: 3099RT8009-18GB Datasheet

MFR RecommendedRFQ

RT8009-18GJ5

Richtek USA Inc.In Stock: 7357RT8009-18GJ5 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the LM3674MF-1.8 is determined by the following critical parameters:

• Output Voltage: 1.8V fixed (all substitutes must match)
• Input Voltage Range: 2.7V to 5.5V minimum compatibility
• Package Type: SOT-23-5 or TSOT-23-5 (pin-compatible)
• Topology: Buck switching regulator with synchronous rectifier
• Output Current: Minimum 500mA (substitutes with 600mA or higher are direct replacements; 250mA is limited-use only)
• Switching Frequency: 1.2MHz to 2MHz range acceptable
• RoHS Compliance: Active substitutes must meet ROHS3 compliance for new designs

Substitutes are grouped into two categories: direct replacements (matching or exceeding 600mA output) and limited-use alternatives (lower current capacity).

Parameter Comparison

Engineering Selection Recommendations

Direct Replacement (Preferred for New Designs):

LM3674MF-1.8/NOPB is the primary substitute. It is the same base product from Texas Instruments with identical electrical specifications and package, but carries active product status and ROHS3 compliance. This part is suitable for direct PCB substitution without design modifications.

Alternative Direct Replacements (600mA Output):

RT8009-18GB and RT8009-18GJ5 from Richtek USA Inc. provide 600mA output current matching the original specification. Both maintain the 1.8V fixed output, 2.5V–5.5V input range, and synchronous rectifier topology. RT8009-18GJ5 uses TSOT-23-5 packaging (thin variant), while RT8009-18GB uses standard SC-74A, SOT-753. Both are ROHS3 compliant and active products. MSL rating of 3 requires 168-hour dry storage consideration.

Limited-Use Alternative (500mA Output):

MCP1603T-180I/OS from Microchip Technology provides 500mA output current, which is below the original 600mA specification. This part is suitable only for applications where the load current does not exceed 500mA. It offers the widest operating temperature range (-40°C to 125°C TJ) and ROHS3 compliance. Package is SOT-23-5 Thin (TSOT-23-5).

Not Recommended for Direct Substitution:

MAX1734EUK18+T from Analog Devices Inc./Maxim Integrated provides only 250mA output current, significantly below the 600mA requirement. This part is unsuitable for applications requiring the full 600mA output capacity and should be considered only for designs with substantially reduced current demands.

Frequently Asked Questions (FAQ)

Q: Can I use MAX1734EUK18+T as a direct replacement for LM3674MF-1.8?

A: No. The MAX1734EUK18+T is rated for 250mA output current, while the LM3674MF-1.8 is rated for 600mA. Use this part only if your application requires 250mA or less. For full 600mA capacity, select LM3674MF-1.8/NOPB, RT8009-18GB, or RT8009-18GJ5.

Q: What is the difference between RT8009-18GB and RT8009-18GJ5?

A: Both parts are identical in electrical specifications and output current (600mA). The primary difference is packaging: RT8009-18GB uses standard SC-74A, SOT-753, while RT8009-18GJ5 uses SOT-23-5 Thin (TSOT-23-5). Select based on your PCB layout requirements and available board space.

Q: Is MCP1603T-180I/OS compatible with my design if I only need 500mA?

A: Yes, if your application load current does not exceed 500mA. The MCP1603T-180I/OS maintains all other critical parameters: 1.8V fixed output, 2.7V–5.5V input range, 2MHz switching frequency, and synchronous rectifier operation. Verify your actual load current before selection.

Q: Why is LM3674MF-1.8/NOPB preferred over the original LM3674MF-1.8?

A: LM3674MF-1.8/NOPB is the active product variant with identical electrical and mechanical specifications. The original LM3674MF-1.8 is obsolete. LM3674MF-1.8/NOPB carries ROHS3 compliance, making it suitable for new designs and production. The "/NOPB" designation indicates no-lead plating (lead-free).

Q: Are all substitutes pin-compatible with the original LM3674MF-1.8?

A: All listed substitutes use SOT-23-5 or TSOT-23-5 packaging, which are pin-compatible. However, verify pinout diagrams for each manufacturer, as internal die and performance characteristics may differ. PCB layout and decoupling capacitor values should be reviewed per each substitute's datasheet.

Q: What does MSL 3 (168 Hours) mean for RT8009 parts?

A: MSL (Moisture Sensitivity Level) 3 indicates the component requires dry storage and has a 168-hour floor life after moisture exposure. Parts must be stored in dry conditions and baked before reflow soldering if exposed to humidity. The original LM3674MF-1.8 and LM3674MF-1.8/NOPB have MSL 1 (unlimited), requiring no special moisture handling.

Q: Can I use MCP1603T-180I/OS in a design originally specified for 600mA output?

A: Only if you have verified that your actual load current does not exceed 500mA. The MCP1603T-180I/OS is rated for 500mA maximum continuous output. Exceeding this rating will cause thermal shutdown or component damage. If your design requires the full 600mA capacity, use LM3674MF-1.8/NOPB, RT8009-18GB, or RT8009-18GJ5.