MMBFJ309 Equivalent & Substitute Parts

Part Overview

The MMBFJ309 is an RF MOSFET JFET N-Channel transistor manufactured by onsemi, designed for RF applications operating at 450 MHz with 12 dB gain. The device is housed in a SOT-23-3 (TO-236-3) surface mount package and rated for 10 V test voltage with 30 mA current rating. The MMBFJ309 is classified as obsolete product status. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production and field replacements.

Substiute Parts

MMBFJ309

onsemiIn Stock: 18575MMBFJ309 Datasheet

Current PartRFQ

MMBFJ310LT1G

onsemiIn Stock: 33865MMBFJ310LT1G Datasheet

DirectRFQ

MMBFJ310LT3G

onsemiIn Stock: 9302MMBFJ310LT3G Datasheet

DirectRFQ

MMBFU310LT1G

onsemiIn Stock: 28463MMBFU310LT1G Datasheet

DirectRFQ

SMMBFJ309LT1G

onsemiIn Stock: 24120SMMBFJ309LT1G Datasheet

DirectRFQ

SMMBFJ310LT3G

onsemiIn Stock: 26754SMMBFJ310LT3G Datasheet

DirectRFQ

2SK3557-6-TB-E

onsemiIn Stock: 482152SK3557-6-TB-E Datasheet

SimilarRFQ

2SK3557-7-TB-E

onsemiIn Stock: 65022SK3557-7-TB-E Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MMBFJ309 is determined by electrical and mechanical compatibility across the following key parameters:

Primary Substitution Criteria:

• Technology: JFET N-Channel configuration
• Package: SOT-23-3 (TO-236-3) surface mount form factor
• Voltage Rating: Minimum 25 V rated voltage
• Test Voltage: 10 V test voltage compatibility
• Gain: 12 dB specification
• Current Rating: Minimum 30 mA capability
• Compliance: RoHS3 and REACH compliance

Direct Substitutes maintain all critical RF and electrical parameters while offering active product status. These parts are functionally equivalent for RF applications at 450 MHz.

Similar Substitutes share the same package and N-Channel JFET technology but operate at different voltage levels (5 V test voltage, 15 V rated voltage) and lower frequency specifications. These parts are suitable for applications where RF frequency and gain specifications differ from the original design.

Parameter Comparison

Engineering Selection Recommendations

Direct Substitutes (Recommended for RF 450 MHz Applications):

MMBFJ310LT1G and MMBFJ310LT3G are the primary direct substitutes for the obsolete MMBFJ309. Both parts maintain the 12 dB gain specification, 10 V test voltage, and SOT-23-3 package. These parts are in active product status and offer improved current rating (60 mA versus 30 mA). The primary difference is packaging format: MMBFJ310LT1G is supplied in Cut Tape (CT) & Digi-Reel format, while MMBFJ310LT3G is supplied in Tape & Reel (TR) format. Both are ROHS3 compliant with unlimited moisture sensitivity level.

Automotive-Grade Alternatives:

SMMBFJ310LT3G provides an automotive-qualified equivalent (AEC-Q101) with identical electrical specifications to MMBFJ310LT3G. This part is suitable for applications requiring automotive-grade components and is supplied in Tape & Reel format. SMMBFJ309LT1G is an automotive-grade alternative with the original 30 mA current rating, supplied in Tape & Reel format.

Similar Substitutes (Lower Voltage Applications):

2SK3557-6-TB-E and 2SK3557-7-TB-E are similar JFET N-Channel devices in SOT-23-3 packages but operate at 5 V test voltage and 15 V rated voltage. These parts feature lower noise figure (1 dB) and are suitable for applications where RF frequency and gain specifications differ from the original 450 MHz, 12 dB design. These parts are in active product status and ROHS3 compliant.

MMBFU310LT1G Consideration:

MMBFU310LT1G is an N-Channel JFET with 25 V rated voltage and 225 mW power rating. While it shares the SOT-23-3 package and N-Channel configuration, it lacks the specific RF gain and frequency specifications of the MMBFJ309. This part is suitable for general-purpose JFET applications but not for RF 450 MHz designs requiring 12 dB gain.

Frequently Asked Questions (FAQ)

Q: Can MMBFJ310LT1G and MMBFJ310LT3G be used interchangeably with MMBFJ309?

A: Yes. Both parts are direct electrical equivalents with identical test voltage (10 V), rated voltage (25 V), gain (12 dB), and package (SOT-23-3). The difference is packaging format: LT1G is Cut Tape & Digi-Reel, while LT3G is Tape & Reel. Selection depends on procurement and assembly requirements.

Q: What is the difference between standard and automotive-grade substitutes?

A: SMMBFJ310LT3G and SMMBFJ309LT1G carry AEC-Q101 automotive qualification, indicating compliance with automotive reliability and quality standards. These parts are suitable for automotive applications where qualification is required. Standard parts (MMBFJ310LT1G, MMBFJ310LT3G) are not automotive-qualified.

Q: Can 2SK3557 series parts replace MMBFJ309 in RF 450 MHz applications?

A: No. The 2SK3557-6-TB-E and 2SK3557-7-TB-E operate at 5 V test voltage and 15 V rated voltage, with different noise figure (1 dB) and no specified gain or frequency characteristics. These parts are suitable for lower-voltage applications but not for RF designs requiring 450 MHz operation and 12 dB gain.

Q: Is MMBFU310LT1G a suitable replacement for MMBFJ309?

A: MMBFU310LT1G shares the SOT-23-3 package and N-Channel JFET technology but lacks RF gain and frequency specifications. It is suitable for general-purpose JFET applications but not for RF 450 MHz designs requiring 12 dB gain.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed (MMBFJ310LT1G, MMBFJ310LT3G, MMBFU310LT1G, SMMBFJ309LT1G, SMMBFJ310LT3G, 2SK3557-6-TB-E, 2SK3557-7-TB-E) are ROHS3 compliant with moisture sensitivity level 1 (unlimited).

Q: What is the current rating difference between MMBFJ309 and MMBFJ310 series?

A: MMBFJ309 is rated for 30 mA, while MMBFJ310LT1G and MMBFJ310LT3G are rated for 60 mA. The higher current rating of the MMBFJ310 series provides additional design margin for applications requiring higher drain current.

Q: Can packaging format (Cut Tape vs. Tape & Reel) affect electrical performance?

A: No. Packaging format affects only procurement, storage, and assembly processes. Electrical performance is identical between MMBFJ310LT1G (Cut Tape) and MMBFJ310LT3G (Tape & Reel).