BF245B_D27Z Equivalent & Substitute Parts

Part Overview

The BF245B_D27Z is an RF MOSFET JFET transistor manufactured by onsemi, housed in a TO-92-3 through-hole package. This device is classified as obsolete, indicating it is no longer in active production. The BF245B_D27Z operates at a rated voltage of 30 V with a maximum current rating of 15 mA, designed for RF applications requiring N-channel JFET configuration.

Due to its obsolete status, locating replacement inventory becomes necessary for ongoing production, maintenance, or repair applications. Active substitute parts with equivalent electrical characteristics and compatible configurations are available to ensure design continuity and supply chain reliability.

Substiute Parts

BF245B_D27Z

onsemiIn Stock: 865BF245B_D27Z Datasheet

Current PartRFQ

MMBF5485

onsemiIn Stock: 65234MMBF5485 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BF245B_D27Z is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Technology: JFET (Junction Field-Effect Transistor)
• Configuration: N-Channel
• Voltage Rating: Substitute must support minimum 30 V rated voltage or equivalent operational voltage
• Current Rating: Substitute must support minimum 15 mA current capability

Mechanical Compatibility Criteria:

• Package Type: Substitute may differ in form factor (through-hole to surface mount conversion acceptable with appropriate PCB layout modifications)
• Mounting Type: Surface mount alternatives are acceptable for redesigned applications

Compliance & Environmental Criteria:

• Moisture Sensitivity Level: MSL 1 (Unlimited) preferred
• REACH Status: REACH Unaffected preferred
• Product Status: Active status preferred for long-term availability

The MMBF5485 qualifies as a substitute based on matching JFET technology, N-channel configuration, and onsemi manufacturer origin. Although the MMBF5485 operates at a lower rated voltage (25 V) and reduced current rating (10 mA), it functions within the electrical envelope of the BF245B_D27Z for applications not requiring the full 30 V or 15 mA specifications. The primary trade-off involves package format conversion from through-hole TO-92-3 to surface-mount SOT-23-3.

Parameter Comparison

Engineering Selection Recommendations

Product Status Consideration: The BF245B_D27Z is classified as obsolete, whereas the MMBF5485 maintains active product status with onsemi. Active status ensures continued manufacturing support, documented availability, and supply chain reliability for future procurement cycles.

Compliance & Certification Alignment: Both the BF245B_D27Z and MMBF5485 share identical REACH Status (REACH Unaffected) and Moisture Sensitivity Level (MSL 1 - Unlimited), ensuring equivalent environmental and regulatory compliance profiles. Both devices carry ECCN classification EAR99, maintaining consistent export control compliance.

Electrical Parameter Derating: The MMBF5485 operates at reduced voltage (25 V versus 30 V) and current (10 mA versus 15 mA) ratings. Selection of the MMBF5485 is appropriate for applications where the BF245B_D27Z operates below its maximum specifications. Applications requiring full 30 V or 15 mA performance must evaluate alternative substitutes or implement design modifications.

Package Format Transition: Substitution from through-hole TO-92-3 to surface-mount SOT-23-3 requires PCB layout redesign. This transition is standard practice in component obsolescence management and does not present technical barriers for new designs or redesigned legacy applications.

Frequently Asked Questions (FAQ)

Q: Can the MMBF5485 directly replace the BF245B_D27Z in existing through-hole PCB designs?

A: Direct physical replacement is not possible due to package format differences. The BF245B_D27Z uses through-hole TO-92-3 leads, while the MMBF5485 uses surface-mount SOT-23-3 pads. PCB layout modification is required. Alternatively, surface-mount to through-hole adapter boards are available as interim solutions for prototype or low-volume applications.

Q: What are the electrical limitations when substituting MMBF5485 for BF245B_D27Z?

A: The MMBF5485 is rated for 25 V maximum (versus 30 V) and 10 mA maximum current (versus 15 mA). Applications operating the BF245B_D27Z at or near these maximum ratings require verification that the MMBF5485 operates within acceptable performance margins. Applications using the BF245B_D27Z below these thresholds are compatible with the MMBF5485.

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

A: No. Both devices share identical REACH Status (REACH Unaffected), Moisture Sensitivity Level (MSL 1), and ECCN classification (EAR99). Regulatory and environmental compliance profiles are equivalent.

Q: Why is the MMBF5485 listed as a substitute despite lower voltage and current ratings?

A: The MMBF5485 qualifies as a substitute based on matching core technology (JFET), configuration (N-Channel), and manufacturer (onsemi). The reduced ratings represent a derating scenario rather than incompatibility. Applications designed within the MMBF5485 envelope benefit from active product status and improved supply availability.

Q: What is the significance of the MMBF5485 having specified frequency and noise figure parameters?

A: The MMBF5485 datasheet provides 400 MHz frequency and 4 dB noise figure specifications, whereas the BF245B_D27Z does not specify these parameters. These additional specifications indicate the MMBF5485 is characterized for RF applications and may offer improved performance documentation for design validation in frequency-dependent circuits.

Q: Are there other substitute options beyond MMBF5485?

A: The MMBF5485 datasheet lists additional substitutes (SMMBFJ310LT1G, MMBF4392LT1G, MMBFJ310LT3G, MMBF4391LT1G, MMBFU310LT1G). These alternatives share JFET technology and N-channel configuration but require individual parameter comparison for specific application requirements.