SI8540-B-FSR Equivalent & Substitute Parts

Part Overview

The SI8540-B-FSR is a current sense amplifier manufactured by Skyworks Solutions Inc., designed for single-circuit current sensing applications. This device operates across a 5V to 36V supply range and is housed in an 8-SOIC surface mount package. The SI8540-B-FSR is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support, production continuity, and component procurement.

Substiute Parts

SI8540-B-FSR

Skyworks Solutions Inc.In Stock: 932SI8540-B-FSR Datasheet

Current PartRFQ

SI8540-B-FWR

Skyworks Solutions Inc.In Stock: 62124SI8540-B-FWR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SI8540-B-FSR are identified based on strict electrical and mechanical compatibility criteria. The primary substitution logic is based on the following parameters:

Electrical Compatibility Parameters:

• Amplifier Type: Current Sense
• Number of Circuits: 1
• Current - Supply: 90µA
• Current - Output / Channel: 10 mA
• Voltage - Supply Span: 5V to 36V
• Operating Temperature Range: -40°C ~ 85°C

Mechanical Compatibility Parameters:

• Mounting Type: Surface Mount
• Base Product Number: SI8540 (same silicon design)
• Manufacturer: Skyworks Solutions Inc.

The SI8540-B-FWR qualifies as a direct substitute because it maintains identical electrical specifications and derives from the same base product design. The primary difference is the package format: the substitute uses SOT-23-5 packaging instead of 8-SOIC, which affects board layout and footprint but does not alter functional performance or electrical characteristics.

Parameter Comparison

Engineering Selection Recommendations

SI8540-B-FWR as Primary Substitute:

The SI8540-B-FWR is the direct functional equivalent of the SI8540-B-FSR. Both devices share identical electrical specifications, supply current characteristics, output current capabilities, and operating temperature ranges. Both are classified as obsolete products from Skyworks Solutions Inc. and carry the same export classification (EAR99) and tariff code (8542.33.0001).

Package Consideration:

The primary distinction between these parts is the package format. The SI8540-B-FSR uses 8-SOIC packaging, while the SI8540-B-FWR uses SOT-23-5 packaging. This difference requires PCB layout modification and footprint redesign. The SOT-23-5 package is smaller and more compact than the 8-SOIC package, which may provide space advantages in constrained board designs.

Moisture Sensitivity Difference:

The SI8540-B-FSR carries MSL 2A (4 Weeks), while the SI8540-B-FWR carries MSL 3 (168 Hours). This difference affects component storage and handling procedures. The substitute part requires more frequent reflow processing or dry-pack storage management.

Compliance and Certification:

Both parts maintain identical export and tariff classifications, ensuring regulatory compliance equivalence for international procurement and supply chain operations.

Frequently Asked Questions (FAQ)

Q: Can the SI8540-B-FWR directly replace the SI8540-B-FSR without design changes?

A: The SI8540-B-FWR provides electrical equivalence but requires PCB footprint modification due to different package formats. The 8-SOIC package cannot be directly substituted with SOT-23-5 without layout redesign.

Q: Are the electrical specifications identical between these two parts?

A: Yes. Both parts operate at 90µA supply current, deliver 10 mA output per channel, support 5V to 36V supply range, and function across -40°C to 85°C operating temperature. The silicon design is identical.

Q: What is the significance of the different MSL ratings?

A: MSL 2A (4 Weeks) for the SI8540-B-FSR allows longer shelf life before reflow processing compared to MSL 3 (168 Hours) for the SI8540-B-FWR. The substitute part requires more frequent moisture bake-out procedures or shorter storage intervals.

Q: Why are both parts classified as obsolete?

A: Obsolete status indicates these products are no longer in active production by Skyworks Solutions Inc. Existing inventory may be available through authorized distributors, but long-term availability is not guaranteed.

Q: Are there any functional differences in current sensing performance?

A: No. Both the SI8540-B-FSR and SI8540-B-FWR deliver identical current sensing amplification, output impedance characteristics, and frequency response within the specified operating parameters.

Q: What are the export compliance implications of using the SI8540-B-FWR?

A: Both parts carry identical EAR99 classification and HTSUS code 8542.33.0001, ensuring equivalent export compliance status for international supply chain operations.

Q: Is the SOT-23-5 package suitable for high-density PCB applications?

A: The SOT-23-5 package is smaller than 8-SOIC, which may provide advantages in space-constrained designs. However, package selection depends on specific board layout requirements and thermal management considerations.