LM3674MFX-1.5 Equivalent & Substitute Parts

Part Overview

The LM3674MFX-1.5 is a buck switching regulator IC manufactured by Texas Instruments, designed for positive fixed 1.5V output applications with 600mA current capacity. This device operates in the SC-74A (SOT-753) package and is classified as obsolete. Due to its obsolete status, identifying active equivalent and substitute parts is essential for ongoing design support, production continuity, and system reliability in applications requiring 1.5V buck regulation with synchronous rectification.

Substiute Parts

LM3674MFX-1.5

Texas InstrumentsIn Stock: 740LM3674MFX-1.5 Datasheet

Current PartRFQ

ADP2108AUJZ-1.5-R7

Analog Devices Inc.In Stock: 3539ADP2108AUJZ-1.5-R7 Datasheet

MFR RecommendedRFQ

MCP1603T-150I/OS

Microchip TechnologyIn Stock: 1136MCP1603T-150I/OS Datasheet

MFR RecommendedRFQ

RT8009-15GJ5

Richtek USA Inc.In Stock: 1074RT8009-15GJ5 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LM3674MFX-1.5 is determined by the following critical parameters:

• Fixed output voltage of 1.5V
• Buck topology with synchronous rectification
• Output current capability of 600mA or greater
• Input voltage range compatibility (minimum 2.7V, maximum 5.5V)
• Surface mount packaging in SOT-23-5 or equivalent form factor
• Single output configuration

The substitute parts identified below meet these core electrical and mechanical requirements. Differences in switching frequency, operating temperature range, and compliance status are noted but do not preclude functional substitution when application constraints permit.

Parameter Comparison

Engineering Selection Recommendations

ADP2108AUJZ-1.5-R7 (Analog Devices Inc.) is the primary recommended substitute. This part maintains 600mA output current matching the original specification, operates across the required input voltage range, and is actively manufactured with ROHS3 compliance. The extended operating temperature range (-40°C to 125°C) provides broader environmental coverage than the original device. Package compatibility is confirmed through SOT-23-5 Thin (TSOT-23-5) form factor, which is mechanically and electrically compatible with the original SC-74A footprint for surface mount applications.

MCP1603T-150I/OS (Microchip Technology) serves as a secondary substitute option. This part meets the 1.5V fixed output and input voltage requirements with active product status and ROHS3 compliance. Output current is rated at 500mA, which is 100mA below the original specification. This part is suitable for applications where the full 600mA output current is not required. Extended operating temperature range (-40°C to 125°C) and SOT-23-5 Thin packaging ensure compatibility.

RT8009-15GJ5 (Richtek USA Inc.) provides an alternative with 600mA output current capacity and active product status. This part operates at a lower switching frequency (1.25MHz) compared to the original 2MHz specification. ROHS3 compliance and SOT-23-5 Thin packaging are confirmed. Operating temperature range extends to -40°C with an upper limit of 85°C, matching the original device's thermal ceiling.

All three substitute parts are actively manufactured, ROHS3 compliant, and available in compatible surface mount packages. Selection should be based on specific application requirements regarding output current demand, switching frequency constraints, and thermal operating conditions.

Frequently Asked Questions (FAQ)

Q: Can the ADP2108AUJZ-1.5-R7 directly replace the LM3674MFX-1.5 without PCB modifications?

A: The ADP2108AUJZ-1.5-R7 uses SOT-23-5 Thin (TSOT-23-5) packaging, which is mechanically compatible with the original SC-74A (SOT-753) footprint for surface mount applications. Pin configuration and electrical characteristics are compatible. No PCB modifications are required for direct substitution.

Q: Why is the MCP1603T-150I/OS rated for only 500mA output current?

A: The MCP1603T-150I/OS is designed with a 500mA output current specification. This part is suitable for applications requiring 1.5V regulation at currents up to 500mA. Applications demanding the full 600mA output current should use ADP2108AUJZ-1.5-R7 or RT8009-15GJ5.

Q: What is the significance of the different switching frequencies among substitute parts?

A: Switching frequency affects output filter design, electromagnetic interference (EMI) characteristics, and efficiency at different load conditions. The original LM3674MFX-1.5 operates at 2MHz. Substitute parts operate at 1.25MHz (RT8009-15GJ5), 2MHz (MCP1603T-150I/OS), or 3MHz (ADP2108AUJZ-1.5-R7). Application-specific filter and layout considerations may apply based on the selected substitute.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. ADP2108AUJZ-1.5-R7, MCP1603T-150I/OS, and RT8009-15GJ5 are all ROHS3 compliant. The original LM3674MFX-1.5 is RoHS non-compliant. Substitution with any of these parts satisfies ROHS3 regulatory requirements.

Q: What is the input voltage range compatibility across all parts?

A: All substitute parts accept input voltages from 2.3V to 5.5V (ADP2108AUJZ-1.5-R7) or higher minimum thresholds. The original LM3674MFX-1.5 requires 2.7V minimum input. ADP2108AUJZ-1.5-R7 offers the lowest minimum input voltage at 2.3V, providing additional design flexibility for lower-voltage supply applications.

Q: Can these substitute parts be used interchangeably in the same application?

A: Interchangeability depends on specific application requirements. All three parts deliver 1.5V fixed output with synchronous buck regulation in compatible packages. Differences in output current rating (500mA vs. 600mA), switching frequency, and operating temperature range must be evaluated against application load, thermal, and EMI constraints before selecting a substitute.