FSUSB31UMX USB Switch IC Equivalent & Substitute Parts

Part Overview

The FSUSB31UMX is a USB Switch IC manufactured by onsemi, designed for high-speed USB 2.0 applications requiring single-channel DPST (Double Pole Single Throw) switching functionality. This component operates as a 2:1 multiplexer/demultiplexer with break-before-make switching characteristics, enabling reliable USB signal routing in portable and embedded systems.

The FSUSB31UMX is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support long-term product maintenance and manufacturing operations.

Substiute Parts

FSUSB31UMX

onsemiIn Stock: 2445FSUSB31UMX Datasheet

Current PartRFQ

FSUSB31K8X

onsemiIn Stock: 4575FSUSB31K8X Datasheet

SimilarRFQ

FSUSB31L8X

Fairchild SemiconductorIn Stock: 4236FSUSB31L8X Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FSUSB31UMX are qualified based on strict electrical and mechanical parameter alignment. The following criteria determine substitution eligibility:

Electrical Parameters (Must Match):

• Switch Circuit Type: DPST
• Multiplexer/Demultiplexer Circuit: 2:1
• Number of Channels: 1
• On-State Resistance (Max): 10 Ohm
• Voltage - Supply, Single (V+): 3V ~ 4.3V
• -3dB Bandwidth: 720 MHz
• Features: Break-Before-Make, USB 2.0
• Operating Temperature: -40°C ~ 85°C (TA)

Mechanical Parameters (Must Match or Be Compatible):

• Mounting Type: Surface Mount
• Package / Case: 8-UFQFN or equivalent 8-pin micro packages

The FSUSB31UMX has two qualified substitutes: FSUSB31K8X and FSUSB31L8X. Both parts maintain identical electrical specifications and operate within the same thermal and voltage ranges. Package variations exist but remain compatible with 8-pin surface-mount footprints used in FSUSB31UMX designs.

Parameter Comparison

Engineering Selection Recommendations

FSUSB31K8X (onsemi): This substitute maintains identical electrical specifications and thermal operating range. The package differs from the main part (8-VFSOP versus 8-UFQFN), requiring PCB footprint verification before implementation. Both parts share obsolete product status. REACH compliance is confirmed for this substitute.

FSUSB31L8X (Fairchild Semiconductor): This substitute provides active product status, offering superior long-term availability compared to the obsolete FSUSB31UMX. Electrical specifications and operating temperature range are identical. The package matches the main part (8-UFQFN), eliminating footprint redesign requirements. This substitute is the preferred choice for new designs or long-term production continuity.

Selection between substitutes depends on design constraints: FSUSB31K8X requires package compatibility verification; FSUSB31L8X eliminates package concerns and provides active product status support.

Frequently Asked Questions (FAQ)

Q: Can FSUSB31K8X be used as a direct replacement for FSUSB31UMX?

A: FSUSB31K8X matches all electrical specifications but uses a different package (8-VFSOP versus 8-UFQFN). PCB footprint compatibility must be verified. If the existing design accommodates 8-VFSOP pinout and dimensions, substitution is electrically valid.

Q: Why is FSUSB31L8X recommended over FSUSB31K8X?

A: FSUSB31L8X maintains active product status, ensuring continued availability and manufacturing support. It also uses the same 8-UFQFN package as the main part, eliminating footprint redesign. Both parts are electrically equivalent.

Q: What are the package differences between these parts?

A: FSUSB31UMX and FSUSB31L8X both use 8-UFQFN packaging. FSUSB31K8X uses 8-VFSOP (0.091", 2.30mm Width). While both are 8-pin surface-mount packages, physical dimensions and pinout layouts differ. PCB layout compatibility must be confirmed before substitution.

Q: Are all three parts compliant with REACH regulations?

A: FSUSB31UMX and FSUSB31K8X are confirmed REACH Unaffected. FSUSB31L8X compliance status is not specified in available documentation.

Q: What is the significance of the 720 MHz bandwidth specification?

A: The 720 MHz -3dB bandwidth ensures signal integrity for USB 2.0 high-speed applications (480 Mbps). All three parts meet this requirement, confirming functional equivalence for USB switching applications.

Q: Can these parts be used interchangeably in existing production?

A: Electrical interchangeability is confirmed. Package compatibility must be verified against existing PCB designs. FSUSB31L8X offers the lowest implementation risk due to matching package and active product status.