TXC CORPORATION 7B25000021 Crystal Equivalent & Substitute Parts

Part Overview

The TXC CORPORATION 7B25000021 is a 25 MHz fundamental mode crystal oscillator in 4-SMD, No Lead surface mount package. This component operates at 25.0000 MHz with ±20ppm frequency tolerance and 8pF load capacitance. The part is classified as obsolete, necessitating identification of active substitute components that maintain electrical and mechanical compatibility for new designs and production continuity.

Substiute Parts

7B25000021

TXC CORPORATIONIn Stock: 9657B25000021 Datasheet

Current PartRFQ

7V-25.000MDIQ-T

TXC CORPORATIONIn Stock: 96837V-25.000MDIQ-T Datasheet

SimilarRFQ

FA-238 25.0000MA30V-K5

EPSONIn Stock: 816FA-238 25.0000MA30V-K5 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 7B25000021 is determined by strict alignment of the following critical parameters:

Mandatory Matching Parameters:

• Frequency: 25.0000 MHz
• Frequency Tolerance: ±20ppm
• Frequency Stability: ±30ppm
• Operating Mode: Fundamental
• Operating Temperature Range: -20°C to 70°C
• Mounting Type: Surface Mount
• Package / Case: 4-SMD, No Lead
• RoHS Compliance Status

Allowable Variation Parameters:

• Load Capacitance: Substitute parts may operate at 10pF (higher than original 8pF) provided the circuit design accommodates this specification
• ESR (Equivalent Series Resistance): Substitute parts may vary from 40 Ohms (original) to 50-60 Ohms within acceptable circuit operating margins
• Physical Dimensions: Substitute parts may differ in length, width, and height while maintaining 4-SMD, No Lead package compatibility and PCB footprint equivalence
• Product Status: Active substitute parts are preferred over obsolete originals for production continuity

The two identified substitute parts meet all mandatory parameters and are classified as active products with current manufacturing availability.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: TXC CORPORATION 7V-25.000MDIQ-T

The 7V-25.000MDIQ-T is the preferred substitute for the obsolete 7B25000021. Both components are manufactured by TXC CORPORATION and share identical frequency, tolerance, stability, and operating temperature specifications. The 7V series is classified as active product with significantly higher inventory availability (9632 pcs vs. 899 pcs). ROHS3 compliance status exceeds the original RoHS Compliant rating. The 10pF load capacitance and 60 Ohms ESR are within acceptable engineering parameters for 25 MHz crystal applications. Physical dimensions are reduced (3.20 x 2.50 mm vs. 5.00 x 3.20 mm), providing improved PCB space efficiency. Tape & Reel packaging supports automated assembly processes.

Secondary Substitute: EPSON FA-238 25.0000MA30V-K5

The FA-238 25.0000MA30V-K5 provides an alternative from EPSON with identical frequency, tolerance, and stability specifications. This component meets all mandatory electrical parameters and operates within the same temperature range. The 10pF load capacitance and 50 Ohms ESR are compatible with standard 25 MHz crystal circuit designs. ROHS3 compliance and MSL 1 rating match the primary substitute. Physical dimensions (3.20 x 2.50 mm) and height (0.70 mm) are optimized for compact PCB layouts. Inventory availability (792 pcs) supports production requirements. Selection of this substitute introduces multi-source component strategy with EPSON as alternative manufacturer.

Substitution Constraints:

Load capacitance increase from 8pF to 10pF requires circuit design verification to confirm oscillator loop stability and frequency accuracy within specified tolerance bands. ESR variation (40 Ohms to 50-60 Ohms) may affect startup characteristics and power consumption; circuit simulation or prototype testing is necessary to validate performance in specific applications. Physical dimension reduction enables improved PCB layout but requires footprint verification for existing designs.

Frequently Asked Questions (FAQ)

Q1: Can the 7V-25.000MDIQ-T directly replace the 7B25000021 without circuit modification?

A: The 7V-25.000MDIQ-T maintains electrical compatibility for frequency, tolerance, stability, and operating temperature. However, the load capacitance increase from 8pF to 10pF may require oscillator circuit tuning. The ESR increase from 40 Ohms to 60 Ohms affects startup behavior. Circuit design review is necessary to confirm performance within specification.

Q2: What is the primary difference between the two substitute parts?

A: Both substitutes operate at identical frequency and tolerance specifications. The TXC 7V-25.000MDIQ-T offers higher inventory availability and same-manufacturer sourcing. The EPSON FA-238 provides multi-source component strategy with lower ESR (50 Ohms vs. 60 Ohms) and reduced height (0.70 mm vs. 0.90 mm). Selection depends on supply chain strategy and circuit performance requirements.

Q3: Are the physical dimensions critical for substitution?

A: The original 7B25000021 measures 5.00 x 3.20 mm, while both substitutes measure 3.20 x 2.50 mm. Both maintain 4-SMD, No Lead package compatibility. Smaller dimensions enable improved PCB space utilization but require footprint verification for existing board designs. Height differences (1.05 mm original vs. 0.90-0.70 mm substitutes) may affect component clearance in confined assembly spaces.

Q4: What compliance certifications apply to these substitute parts?

A: The original 7B25000021 carries RoHS Compliant status. Both substitutes meet ROHS3 Compliant and REACH Unaffected certifications, representing enhanced environmental compliance. All three components carry MSL 1 (Unlimited) moisture sensitivity rating, indicating no special storage or handling requirements.

Q5: Which substitute is recommended for new product designs?

A: The TXC CORPORATION 7V-25.000MDIQ-T is recommended for new designs due to active product status, higher inventory availability, and same-manufacturer continuity. The EPSON FA-238 is suitable for designs requiring multi-source component qualification or where lower ESR and reduced height provide specific performance advantages.

Q6: How does load capacitance affect crystal oscillator performance?

A: Load capacitance determines the frequency at which the crystal resonates in the oscillator circuit. The increase from 8pF to 10pF shifts the resonant frequency slightly. Circuit design must accommodate this specification through appropriate load capacitor selection in the oscillator network to maintain frequency accuracy within ±20ppm tolerance.

Q7: What is the significance of ESR variation between parts?

A: Equivalent Series Resistance affects crystal startup time, power consumption, and oscillation amplitude. The increase from 40 Ohms (original) to 50-60 Ohms (substitutes) may require oscillator circuit adjustment to ensure reliable startup across the -20°C to 70°C operating temperature range. Circuit simulation or prototype validation is recommended.

Q8: Are these parts suitable for high-reliability applications?

A: All three components operate within identical frequency tolerance (±20ppm) and stability (±30ppm) specifications. MSL 1 rating indicates unlimited shelf life without moisture sensitivity concerns. ROHS3 and REACH compliance support environmental and regulatory requirements. Application-specific reliability requirements must be evaluated through circuit performance testing.