FUSB251UCX Equivalent & Substitute Parts

Part Overview

The FUSB251UCX is an active USB Type-C controller with integrated CC and SBU protection functionality. Manufactured by onsemi, this component operates as an I2C interface controller in a 15-WLCSP package. The device is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating (MSL 1). Alternative components may be required due to supply constraints, design optimization, or specific application requirements where substitute electrical and mechanical parameters align with system specifications.

Substiute Parts

FUSB251UCX

onsemiIn Stock: 3855FUSB251UCX Datasheet

Current PartRFQ

RT1738AGQW(2)

Richtek USA Inc.In Stock: 36127RT1738AGQW(2) Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FUSB251UCX is evaluated based on the following critical parameters:

• Voltage Supply Range: Substitute must operate within 2.7V ~ 5.5V
• Operating Temperature Range: Substitute must support -40°C ~ 85°C (TA)
• Product Status: Substitute must maintain Active status for production availability
• Compliance Standards: Substitute must maintain RoHS3 compliance and REACH unaffected status
• Functional Category: Substitute must provide USB Type-C protection or switching functionality
• Package Compatibility: Substitute must be surface-mount compatible with equivalent or superior thermal characteristics

The RT1738AGQW(2) qualifies as a substitute based on overlapping voltage supply range (2.5V ~ 5.5V), matching operating temperature range (-40°C ~ 85°C), Active product status, and equivalent compliance certifications (RoHS3, REACH unaffected). Both components address USB Type-C power delivery and protection requirements within automotive and consumer electronics applications.

Parameter Comparison

Engineering Selection Recommendations

Selection between FUSB251UCX and RT1738AGQW(2) is determined by application-specific requirements and compliance verification:

• FUSB251UCX: Primary selection for I2C-based USB Type-C controller implementations requiring dedicated CC and SBU protection logic with minimal supply current (15µA). Maintains unlimited moisture sensitivity rating (MSL 1) suitable for extended storage and logistics environments.

• RT1738AGQW(2): Alternative selection for applications requiring integrated USB Type-C power switch functionality with 1:1 output configuration and fault protection features (over-temperature, over-voltage, UVLO). Supports higher output current capability (1.25A) with controlled slew rate and load discharge features. Moisture sensitivity level 3 (168 hours) requires controlled storage conditions.

Both components maintain Active product status, RoHS3 compliance, and REACH unaffected designation, confirming regulatory alignment for production deployment.

Frequently Asked Questions (FAQ)

Q: Can RT1738AGQW(2) directly replace FUSB251UCX in existing designs?

A: Direct replacement requires verification of functional requirements. FUSB251UCX operates as an I2C controller for CC and SBU protection, while RT1738AGQW(2) functions as a USB Type-C power switch with integrated fault protection. Both support the same voltage supply range (2.7V ~ 5.5V minimum overlap) and operating temperature (-40°C ~ 85°C). Circuit topology and firmware/software integration must be evaluated for compatibility.

Q: What are the key differences in package specifications?

A: FUSB251UCX uses 15-WLCSP (1.49x2.06mm) wafer-level chip-scale packaging, while RT1738AGQW(2) uses 20-WQFN (3x3mm) with exposed pad. Both are surface-mount technologies suitable for automated assembly. Physical footprint and thermal management characteristics differ; board layout redesign may be required.

Q: Are both components suitable for automotive applications?

A: Both components maintain identical operating temperature range (-40°C ~ 85°C) and equivalent compliance certifications (RoHS3, REACH unaffected, EAR99 ECCN). Automotive qualification status is not specified in provided parameters and must be verified through manufacturer datasheets and application notes.

Q: What is the significance of moisture sensitivity level differences?

A: FUSB251UCX carries MSL 1 (unlimited storage without baking), while RT1738AGQW(2) carries MSL 3 (168-hour maximum storage before reflow). MSL 1 components require less stringent moisture control during logistics and warehousing. MSL 3 components require controlled storage environments and pre-reflow baking procedures per IPC-A-610 standards.

Q: How do supply current specifications compare?

A: FUSB251UCX specifies 15µA supply current, indicating low-power controller operation. RT1738AGQW(2) does not specify supply current but provides output current capability (1.25A maximum). Supply current comparison is not applicable due to different functional classifications (controller vs. power switch driver).