FSUSB20BQX USB Switch IC Equivalent & Substitute Parts

Part Overview

The FSUSB20BQX is a dual 2x1 USB switch IC manufactured by onsemi, designed for USB signal routing applications. This device features a DPDT (Double Pole Double Throw) switch circuit with single-channel operation and is housed in a 14-DQFN package. The part is currently classified as obsolete, making identification of compatible substitute components essential for ongoing design support and production continuity. The FSUSB20BQX operates across a 3V to 3.6V supply range with 6.5Ω maximum on-state resistance and supports USB 2.0 bi-directional switching at 750MHz bandwidth.

Substiute Parts

FSUSB20BQX

onsemiIn Stock: 17750FSUSB20BQX Datasheet

Current PartRFQ

FSUSB42UMX

onsemiIn Stock: 285405FSUSB42UMX Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FSUSB20BQX is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Switch circuit type must be DPDT
• Number of channels must be 1
• On-state resistance maximum of 6.5Ω or lower
• Supply voltage range must encompass or exceed 3V to 3.6V
• Bandwidth must support USB 2.0 operation (minimum 720MHz)
• Operating temperature range must include -40°C to 85°C

Mechanical Compatibility Criteria:

• Surface mount packaging only
• Physical footprint compatibility with application requirements

The FSUSB42UMX qualifies as a direct substitute based on matching DPDT switch topology, single-channel configuration, equivalent on-state resistance, overlapping supply voltage range (2.4V to 4.4V encompasses the FSUSB20BQX requirement), and superior bandwidth specification. The substitute maintains USB 2.0 feature compatibility and identical operating temperature range.

Parameter Comparison

Engineering Selection Recommendations

The FSUSB42UMX is the qualified substitute for the obsolete FSUSB20BQX. Selection is based on the following engineering factors:

Product Status: The FSUSB42UMX maintains active product status with onsemi, ensuring continued availability and manufacturing support. The FSUSB20BQX obsolescence status necessitates transition to an alternative component.

Electrical Equivalence: Both devices share identical DPDT switch topology, single-channel configuration, and 6.5Ω on-state resistance specification. The FSUSB42UMX supply voltage range (2.4V to 4.4V) provides broader operational margin while maintaining compatibility with the FSUSB20BQX requirement window (3V to 3.6V). Bandwidth specifications (720MHz vs. 750MHz) both exceed USB 2.0 protocol requirements.

Compliance & Certifications: Both parts maintain identical Moisture Sensitivity Level (MSL 1), REACH Unaffected status, and EAR99 ECCN classification. The FSUSB42UMX carries RoHS3 compliance certification.

Package Consideration: The FSUSB42UMX uses a smaller 10-UFQFN package compared to the 14-VFQFN of the original part. PCB layout modification is required to accommodate the different footprint and pin count.

Frequently Asked Questions (FAQ)

Q: Can the FSUSB42UMX directly replace the FSUSB20BQX without circuit modification?

A: Electrical substitution is valid. However, the FSUSB42UMX uses a 10-pin UFQFN package versus the 14-pin VFQFN of the FSUSB20BQX, requiring PCB layout redesign and schematic pin mapping verification.

Q: What is the key difference between the FSUSB20BQX and FSUSB42UMX feature sets?

A: The FSUSB20BQX provides bi-directional switching, while the FSUSB42UMX implements break-before-make switching. Both support USB 2.0 operation. Break-before-make topology ensures signal isolation during switching transitions, which may be advantageous in certain applications.

Q: Are the supply voltage ranges compatible?

A: Yes. The FSUSB42UMX supply range (2.4V to 4.4V) encompasses the FSUSB20BQX requirement (3V to 3.6V), providing operational compatibility across the original specification window.

Q: What is the impact of the bandwidth difference (750MHz vs. 720MHz)?

A: Both bandwidth specifications exceed USB 2.0 protocol requirements. The 30MHz difference is not functionally significant for USB 2.0 applications.

Q: Is inventory availability a consideration?

A: The FSUSB42UMX has significantly higher inventory availability (285,300 pcs) compared to the FSUSB20BQX (17,730 pcs), supporting production continuity and supply chain stability.

Q: What certifications apply to both parts?

A: Both devices maintain MSL 1 (Unlimited) moisture sensitivity classification, REACH Unaffected regulatory status, and EAR99 export control classification. The FSUSB42UMX additionally carries RoHS3 compliance.