2N5639 Equivalent & Substitute Parts

Part Overview

The 2N5639 is an N-Channel JFET transistor rated for 35 V breakdown voltage and 310 mW power dissipation in a TO-92 through-hole package. This device is classified as obsolete, making equivalent substitutes necessary for new designs and production continuity. The 2N5639 serves applications requiring low-noise signal amplification and switching in RF and audio circuits where through-hole packaging is required.

Substiute Parts

2N5639

onsemiIn Stock: 10022N5639 Datasheet

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BF256B

onsemiIn Stock: 39931BF256B Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 2N5639 is determined by the following critical parameters:

• Device Type: N-Channel JFET configuration
• Voltage Rating: Drain-Source voltage (Vdss) of 30 V minimum
• Current Capability: Drain current (Idss) of 13 mA or greater
• Package Compatibility: TO-92-3 through-hole package
• Thermal Performance: Power dissipation capability of 310 mW or greater
• Operating Temperature Range: -65°C to 150°C or equivalent

The BF256B qualifies as a direct substitute based on matching N-Channel JFET technology, 30 V voltage rating, compatible TO-92-3 package, and through-hole mounting. The BF256B is an active product with current manufacturing availability and RoHS3 compliance, addressing the obsolescence of the 2N5639.

Parameter Comparison

Engineering Selection Recommendations

The BF256B is the qualified substitute for the 2N5639 based on the following criteria:

• Active Product Status: The BF256B is actively manufactured by onsemi, ensuring long-term availability and supply chain continuity compared to the obsolete 2N5639.
• Regulatory Compliance: The BF256B meets RoHS3 compliance requirements, whereas the 2N5639 is RoHS non-compliant. This is critical for applications subject to environmental regulations.
• Package Compatibility: Both devices use the TO-92-3 through-hole package, enabling direct mechanical and electrical substitution without PCB redesign.
• Voltage and Current Ratings: The BF256B maintains the 30 V Vdss rating required for the application. The drain current rating of 13 mA is lower than the 2N5639's 25 mA; circuit designers must verify that application requirements do not exceed this specification.
• Thermal Considerations: Power dissipation specifications are not provided for the BF256B. Thermal analysis of the specific application is required to confirm adequate heat dissipation in the TO-92 package.

Frequently Asked Questions (FAQ)

Q: Can the BF256B be used as a direct pin-for-pin replacement for the 2N5639?

A: Yes, the BF256B is a direct pin-for-pin replacement in the TO-92-3 package. Both devices have identical lead configurations (Gate, Drain, Source). No PCB modifications are required for mechanical substitution.

Q: What are the key differences between the 2N5639 and BF256B?

A: The primary differences are: (1) Product status—the BF256B is active while the 2N5639 is obsolete; (2) RoHS compliance—the BF256B is RoHS3 compliant; (3) Drain current rating—the BF256B is rated for 13 mA compared to the 2N5639's 25 mA; (4) Regulatory certifications differ between the two devices.

Q: Is the lower drain current rating of the BF256B a limitation?

A: The 13 mA Idss rating of the BF256B must be evaluated against your specific circuit requirements. If the application requires drain currents exceeding 13 mA, the BF256B may not be suitable. Consult detailed datasheets and perform circuit simulation to confirm compatibility.

Q: Are there any thermal considerations when substituting the BF256B for the 2N5639?

A: The 2N5639 is rated for 310 mW maximum power dissipation. Thermal specifications for the BF256B are not provided in the available data. Thermal analysis of your specific application is necessary to ensure the TO-92 package can dissipate the required power without exceeding junction temperature limits.

Q: Does the BF256B meet environmental and regulatory requirements?

A: Yes, the BF256B is RoHS3 compliant and REACH unaffected, meeting current environmental standards. The 2N5639 is RoHS non-compliant, making the BF256B the appropriate choice for applications subject to environmental regulations.

Q: What is the operating temperature range for the BF256B?

A: Operating temperature specifications for the BF256B are not provided in the available data. Refer to the BF256B datasheet for complete thermal and operating condition specifications.