7B-28.63636MBBK-T Crystal Oscillator Equivalent & Substitute Parts

Part Overview

The 7B-28.63636MBBK-T is a 28.63636 MHz fundamental mode crystal oscillator manufactured by TXC CORPORATION, designed for surface mount applications requiring precise frequency control. This component operates at ±50ppm frequency stability with a 20pF load capacitance and 40 Ohms equivalent series resistance (ESR). The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and repair applications.

Substiute Parts

7B-28.63636MBBK-T

TXC CORPORATIONIn Stock: 8187B-28.63636MBBK-T Datasheet

Current PartRFQ

7M-28.63636MBBK-T

TXC CORPORATIONIn Stock: 8187M-28.63636MBBK-T Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 7B-28.63636MBBK-T is determined by strict alignment of the following parameters:

Critical Matching Parameters:

• Frequency: 28.63636 MHz (exact match required)
• Frequency Stability: ±50ppm (exact match required)
• Load Capacitance: 20pF (exact match required)
• Operating Temperature Range: -20°C to 70°C (minimum coverage required)
• Mounting Type: Surface Mount (exact match required)
• Package Type: 4-SMD, No Lead (exact match required)

Allowable Variation Parameters:

• ESR (Equivalent Series Resistance): Substitutes may vary within acceptable circuit design margins
• Physical dimensions: Minor variations permitted if package type classification remains identical
• Product status: Active parts are preferred for obsolete originals

The 7M-28.63636MBBK-T qualifies as a direct substitute based on matching all critical parameters while maintaining the same frequency, stability, load capacitance, temperature range, mounting type, and package classification.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: 7M-28.63636MBBK-T

The 7M-28.63636MBBK-T is the recommended substitute for the obsolete 7B-28.63636MBBK-T based on the following engineering criteria:

1. Electrical Compatibility: All critical electrical parameters match exactly—frequency (28.63636 MHz), frequency stability (±50ppm), and load capacitance (20pF) are identical. The ESR difference (60 Ohms vs. 40 Ohms) represents a 50% increase but remains within acceptable ranges for standard oscillator circuit designs.

2. Physical Compatibility: Both parts use identical 4-SMD, No Lead package classification. The 7M variant features reduced physical dimensions (3.20mm x 2.50mm vs. 5.00mm x 3.20mm) and lower profile (0.80mm vs. 1.05mm), which provides improved PCB space efficiency without compromising electrical function.

3. Regulatory Compliance: Both parts maintain RoHS compliance and MSL 1 (Unlimited) moisture sensitivity rating, ensuring equivalent handling and storage requirements.

4. Product Status: The 7M-28.63636MBBK-T is classified as Active, providing long-term availability and supply chain stability compared to the obsolete 7B variant.

5. Manufacturer Continuity: Both parts are manufactured by TXC CORPORATION, ensuring consistent quality standards and manufacturing processes.

Frequently Asked Questions (FAQ)

Q: Can the 7M-28.63636MBBK-T directly replace the 7B-28.63636MBBK-T without circuit modifications?

A: Yes. The 7M variant maintains identical frequency (28.63636 MHz), frequency stability (±50ppm), load capacitance (20pF), operating temperature range (-20°C to 70°C), and package type (4-SMD, No Lead). The ESR increase from 40 to 60 Ohms is within acceptable design margins for standard oscillator circuits and does not require circuit redesign.

Q: What is the significance of the ESR difference between these parts?

A: ESR (Equivalent Series Resistance) affects crystal startup time and power consumption in oscillator circuits. The 7M variant's 60 Ohms ESR versus the 7B's 40 Ohms represents a 50% increase. This variation is acceptable for most applications but should be verified if the circuit operates at the frequency stability limits or in marginal startup conditions.

Q: Are the physical dimension differences important for PCB layout?

A: The 7M-28.63636MBBK-T is physically smaller (3.20mm x 2.50mm vs. 5.00mm x 3.20mm) and lower profile (0.80mm vs. 1.05mm). If the original PCB footprint was designed for the 7B dimensions, the smaller 7M part will fit within the same footprint area. However, verify that the PCB layout accommodates the reduced height without interference from adjacent components.

Q: Do both parts have identical moisture sensitivity requirements?

A: Yes. Both the 7B-28.63636MBBK-T and 7M-28.63636MBBK-T carry MSL 1 (Unlimited) ratings, indicating unlimited shelf life and no special moisture control requirements during storage or handling.

Q: Is the 7M-28.63636MBBK-T suitable for new designs?

A: Yes. The 7M variant is classified as Active, making it the appropriate choice for new product designs. The 7B variant, being obsolete, should not be specified for new designs.

Q: What compliance certifications apply to both parts?

A: Both parts are RoHS Compliant and carry identical ECCN (EAR99) and HTSUS (8541.60.0060) classifications, ensuring equivalent regulatory and export compliance.