7B-50.000MBBK-T Crystal Oscillator Equivalent & Substitute Parts

Part Overview

The 7B-50.000MBBK-T is a 50 MHz surface mount crystal oscillator manufactured by TXC CORPORATION. This component operates at 50 MHz with ±50ppm frequency stability and 20pF load capacitance in a 4-SMD, No Lead package. 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-50.000MBBK-T

TXC CORPORATIONIn Stock: 11827B-50.000MBBK-T Datasheet

Current PartRFQ

7M-50.000MBBK-T

TXC CORPORATIONIn Stock: 10967M-50.000MBBK-T Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 7B-50.000MBBK-T is determined by the following critical parameters:

Mandatory Matching Parameters:

• Frequency: 50 MHz (exact match required)
• Frequency Stability: ±50ppm (tolerance specification)
• Load Capacitance: 20pF (circuit design requirement)
• Operating Temperature Range: -20°C ~ 70°C (environmental specification)
• Mounting Type: Surface Mount (assembly compatibility)
• Package Type: 4-SMD, No Lead (PCB footprint compatibility)
• RoHS Compliance: Required for regulatory compliance

Allowable Variation Parameters:

• ESR (Equivalent Series Resistance): May vary within circuit design margins
• Operating Mode: May differ (Fundamental vs. 3rd Overtone) provided frequency and stability specifications are maintained
• Physical dimensions: May vary within SMD package classification constraints
• Product Status: Active alternatives preferred for obsolete parts

The 7M-50.000MBBK-T qualifies as a substitute based on matching all mandatory parameters while offering improved product status (Active) and lower ESR performance.

Parameter Comparison

Engineering Selection Recommendations

7M-50.000MBBK-T as Primary Substitute:

The 7M-50.000MBBK-T is the qualified substitute for the obsolete 7B-50.000MBBK-T. Selection is based on the following engineering criteria:

1. Product Status: The 7M series maintains Active status, ensuring continued availability and supply chain reliability compared to the Obsolete 7B series.

2. Electrical Compatibility: Both parts maintain identical frequency (50 MHz), frequency stability (±50ppm), and load capacitance (20pF) specifications. These parameters are critical for circuit operation and are fully matched.

3. Regulatory Compliance: Both parts are RoHS Compliant and carry identical ECCN (EAR99) and HTSUS (8541.60.0060) classifications, ensuring regulatory equivalence.

4. Environmental Specifications: Operating temperature range (-20°C ~ 70°C) and Moisture Sensitivity Level (MSL 1) are identical, confirming environmental compatibility.

5. Package Compatibility: Both parts use 4-SMD, No Lead surface mount packaging. The 7M series features a smaller footprint (3.20mm x 2.50mm vs. 5.00mm x 3.20mm) and lower profile (0.80mm vs. 1.05mm), which is compatible with existing PCB designs and may provide layout advantages.

6. ESR Consideration: The 7M-50.000MBBK-T operates at 60 Ohms ESR compared to 120 Ohms in the 7B series. Lower ESR improves circuit efficiency and reduces power dissipation. This parameter variation is within acceptable substitution margins for 50 MHz crystal applications.

7. Operating Mode Difference: The 7M operates in Fundamental mode while the 7B operates in 3rd Overtone mode. Both modes deliver the specified 50 MHz output frequency and maintain the required frequency stability. This difference does not affect circuit compatibility when frequency and stability specifications are met.

Frequently Asked Questions (FAQ)

Q: Can the 7M-50.000MBBK-T directly replace the 7B-50.000MBBK-T on existing PCBs?

A: Yes. Both parts use identical 4-SMD, No Lead packaging and maintain the same electrical specifications (50 MHz, ±50ppm, 20pF load capacitance). The 7M series has a smaller physical footprint, which is compatible with existing PCB designs. No circuit modifications are required.

Q: What is the significance of the ESR difference (120 Ohms vs. 60 Ohms)?

A: ESR (Equivalent Series Resistance) affects power dissipation and circuit efficiency. The 7M-50.000MBBK-T operates at 60 Ohms, which is lower than the 7B series at 120 Ohms. Lower ESR reduces power consumption and heat generation, representing an improvement in the substitute part. This variation does not compromise circuit functionality.

Q: Why do the two parts operate in different modes (3rd Overtone vs. Fundamental)?

A: Operating mode refers to the crystal's resonance mechanism. The 7B operates in 3rd Overtone mode, while the 7M operates in Fundamental mode. Both modes produce the identical 50 MHz output frequency with ±50ppm stability. The mode difference is internal to the crystal design and does not affect circuit compatibility when frequency specifications are met.

Q: Are there any compliance or regulatory differences between these parts?

A: No. Both parts are RoHS Compliant, carry identical ECCN (EAR99) and HTSUS (8541.60.0060) classifications, and have MSL 1 (Unlimited) moisture sensitivity ratings. They are fully equivalent from a regulatory and compliance perspective.

Q: What is the advantage of the 7M series' smaller size?

A: The 7M-50.000MBBK-T measures 3.20mm x 2.50mm with a maximum seated height of 0.80mm, compared to the 7B's 5.00mm x 3.20mm footprint and 1.05mm height. The smaller dimensions may provide PCB layout advantages and reduce overall component volume without affecting electrical performance.

Q: Is the 7M-50.000MBBK-T suitable for new designs?

A: Yes. The 7M-50.000MBBK-T is classified as Active, making it the appropriate choice for new product designs. It provides the same electrical specifications as the obsolete 7B series with improved availability and supply chain continuity.

Q: What should be verified before implementing the substitution?

A: Verify that your circuit design accommodates the 20pF load capacitance and ±50ppm frequency stability specifications. Both parts meet these requirements. The smaller physical dimensions of the 7M series should be confirmed as compatible with your PCB layout and assembly process.