EPSON FC-255 32.7680K-B Equivalent & Substitute Parts

Part Overview

The EPSON FC-255 32.7680K-B is a 32.768 kHz tuning fork crystal designed for real-time clock (RTC) and timing applications. This component operates at a fundamental frequency with a load capacitance of 16pF and an equivalent series resistance (ESR) of 65 kOhms. The part is mounted as a 2-SMD surface mount device with no leads, measuring 4.90mm × 1.80mm × 0.90mm (max height).

The FC-255 32.7680K-B is classified as obsolete. Equivalent substitute parts are available to maintain design continuity and ensure supply chain reliability for applications requiring this frequency standard.

Substiute Parts

FC-255 32.7680K-B

EPSONIn Stock: 1057FC-255 32.7680K-B Datasheet

Current PartRFQ

FC-135 32.7680KA-A5

EPSONIn Stock: 1000420FC-135 32.7680KA-A5 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FC-255 32.7680K-B is determined by the following critical parameters:

Mandatory Matching Parameters:

• Frequency: 32.768 kHz (exact match required)
• Operating Mode: Fundamental
• Mounting Type: Surface Mount (2-SMD, No Lead)
• Operating Temperature Range: -40°C ~ 85°C (minimum)
• RoHS Compliance: ROHS3 Compliant

Allowable Variation Parameters:

• Frequency Tolerance: The substitute may have tighter tolerance (lower ppm value) than the original ±100ppm specification
• Load Capacitance: The substitute may differ from 16pF; circuit design must accommodate the specified load capacitance
• ESR: The substitute may differ from 65 kOhms; circuit impedance matching must be verified
• Package Dimensions: Minor dimensional variations are acceptable provided the 2-SMD, No Lead form factor is maintained and PCB footprint compatibility is confirmed

The EPSON FC-135 32.7680KA-A5 meets all mandatory matching parameters and qualifies as a direct substitute.

Parameter Comparison

Engineering Selection Recommendations

The EPSON FC-135 32.7680KA-A5 is the qualified substitute for the obsolete FC-255 32.7680K-B. Selection is based on the following factors:

Compliance & Availability:

• The FC-135 maintains ROHS3 compliance and MSL 1 rating, matching the original part's environmental and regulatory requirements
• The FC-135 is classified as Active product status, ensuring ongoing availability and supply chain continuity
• Both parts are manufactured by EPSON, maintaining design consistency

Electrical Compatibility:

• Both parts operate at the identical 32.768 kHz fundamental frequency within the -40°C ~ 85°C temperature range
• The FC-135 provides tighter frequency tolerance (±20ppm versus ±100ppm), which may improve timing accuracy in RTC applications
• Load capacitance differs (12.5pF versus 16pF) and ESR differs (70 kOhms versus 65 kOhms); circuit design parameters must be evaluated for compatibility with these values

Physical Compatibility:

• Both parts use identical 2-SMD, No Lead surface mount packaging
• The FC-135 has a smaller footprint (3.20mm × 1.50mm versus 4.90mm × 1.80mm); PCB layout must accommodate the reduced dimensions

Frequently Asked Questions (FAQ)

Q: Can the FC-135 32.7680KA-A5 be used as a direct replacement for the FC-255 32.7680K-B?

A: Yes, the FC-135 qualifies as a substitute. Both parts operate at 32.768 kHz with identical temperature ranges and mounting types. However, the load capacitance (12.5pF vs. 16pF) and ESR (70 kOhms vs. 65 kOhms) differ. Circuit design parameters must be evaluated to confirm compatibility with these electrical differences.

Q: What is the primary reason to substitute the FC-255 32.7680K-B?

A: The FC-255 is classified as obsolete. The FC-135 is an active product with equivalent electrical and mechanical specifications, ensuring long-term supply availability.

Q: Are there any package compatibility concerns?

A: Both parts use 2-SMD, No Lead surface mount packaging. The FC-135 has a smaller footprint (3.20mm × 1.50mm versus 4.90mm × 1.80mm). PCB layout and footprint design must be verified to accommodate the reduced dimensions.

Q: Does the tighter frequency tolerance of the FC-135 affect compatibility?

A: The FC-135 provides ±20ppm tolerance compared to the FC-255's ±100ppm. Tighter tolerance may improve timing accuracy but does not prevent substitution. The application's frequency tolerance requirements determine whether this difference is beneficial or irrelevant.

Q: What compliance certifications apply to both parts?

A: Both the FC-255 and FC-135 are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating. The FC-135 is additionally REACH Affected. Both parts meet the same environmental and regulatory standards.