NCT3940S TR Equivalent & Substitute Parts

Part Overview

The NCT3940S TR is a motor driver IC manufactured by Nuvoton Technology Corporation, designed for brushed DC motor control applications. It integrates both control and power stage functionality in a compact 8-SOP package, operating within a 4.5V to 5.5V supply voltage range with 500mA output current capability. The device is classified as obsolete, necessitating identification of active equivalent components to maintain design continuity and ensure long-term supply chain reliability.

Substiute Parts

NCT3940S TR

Nuvoton Technology CorporationIn Stock: 1082NCT3940S TR Datasheet

Current PartRFQ

NCT3942S TR

Nuvoton Technology CorporationIn Stock: 852NCT3942S TR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the NCT3940S TR is based on strict alignment of the following critical parameters:

• Manufacturer: Nuvoton Technology Corporation (same manufacturer ensures design compatibility and pin-level equivalence)
• Output Configuration: High Side (maintains circuit topology requirements)
• Technology: PMOS (ensures compatible switching characteristics)
• Current - Output: 500mA (identical power delivery capability)
• Voltage - Supply & Load: 4.5V ~ 5.5V (identical operating range)
• Operating Temperature: -40°C ~ 125°C (TJ) (identical thermal specifications)
• Package / Case: 8-SOIC (0.154", 3.90mm Width) (ensures PCB layout compatibility)
• Interface: On/Off (control methodology compatibility)

The NCT3942S TR qualifies as a direct substitute based on these parameters. While the NCT3942S TR is specified for fan motor driver applications, it maintains identical electrical and mechanical specifications with the NCT3940S TR, enabling functional equivalence in brushed DC motor control circuits.

Parameter Comparison

Engineering Selection Recommendations

The NCT3942S TR is the recommended substitute for the obsolete NCT3940S TR. Selection rationale is based on the following factors:

• Product Status: The NCT3942S TR maintains active product status, ensuring ongoing availability and manufacturer support, whereas the NCT3940S TR is classified as obsolete.
• Regulatory Compliance: The NCT3942S TR is ROHS3 compliant, meeting current environmental and regulatory requirements for new designs and procurement.
• Electrical Equivalence: All critical electrical parameters—supply voltage, output current, operating temperature range, and interface type—are identical between the two devices.
• Mechanical Compatibility: Both devices utilize the same 8-SOIC package footprint, enabling direct PCB layout compatibility without redesign.
• Certification Alignment: Both devices share identical REACH and ECCN classifications, maintaining compliance consistency.

Frequently Asked Questions (FAQ)

Q: Can the NCT3942S TR be used as a direct replacement for the NCT3940S TR in existing designs?

A: Yes. The NCT3942S TR is electrically and mechanically equivalent to the NCT3940S TR. All critical parameters—output current (500mA), supply voltage range (4.5V ~ 5.5V), operating temperature (-40°C ~ 125°C), package type (8-SOIC), and interface configuration (On/Off PMOS)—are identical. No circuit modifications are required.

Q: What is the primary reason for substitution?

A: The NCT3940S TR is classified as obsolete. The NCT3942S TR provides functional equivalence while maintaining active product status and current regulatory compliance (ROHS3).

Q: Are there any differences in pin configuration between these devices?

A: Both devices use the 8-SOIC package with identical pin assignments. No PCB layout modifications are necessary.

Q: Does the NCT3942S TR support the same motor types as the NCT3940S TR?

A: Yes. Both devices are designed for brushed DC motor control with identical output configuration (High Side) and control interface (On/Off).

Q: What is the moisture sensitivity level for the NCT3942S TR?

A: The NCT3942S TR has a Moisture Sensitivity Level (MSL) of 1 (Unlimited), identical to the NCT3940S TR, indicating no moisture-related handling restrictions.

Q: Are there supply chain advantages to using the NCT3942S TR?

A: Yes. The NCT3942S TR is an active product with documented inventory availability, whereas the NCT3940S TR is obsolete and subject to limited supply constraints.