BF494_D27Z Equivalent & Substitute Parts

Part Overview

The BF494_D27Z is an RF transistor NPN manufactured by onsemi, rated for 20V collector-emitter breakdown voltage with a maximum power dissipation of 350mW in a through-hole TO-92-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The BF494_D27Z operates at a maximum junction temperature of 150°C with a DC current gain (hFE) minimum of 67 at 1mA collector current and 10V collector-emitter voltage.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	20	V
Power - Max	350	mW
Current - Collector (Ic) (Max)	30	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	67 @ 1mA, 10V	—
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the BF494_D27Z is determined by the following critical parameters: transistor type (NPN), maximum collector-emitter breakdown voltage, maximum power dissipation, maximum collector current, DC current gain characteristics, and operating temperature range. All substitute parts listed maintain NPN polarity and operate at a maximum junction temperature of 150°C.

The substitute parts are grouped into two categories based on mounting technology:

Surface Mount Substitutes: BFP196WH6327XTSA1, BFP196WNH6327XTSA1, BFQ19SH6327XTSA1, and BFR380FH6327XTSA1 are surface-mount RF transistors manufactured by Infineon Technologies. These devices provide higher frequency capability and improved power handling compared to the original through-hole device.

Through-Hole and Chassis Mount Alternatives: CMPT918 TR PBFREE (Central Semiconductor Corp, surface mount SOT-23) and MRF327 (MACOM Technology Solutions, chassis mount) represent alternative form factors. The MRF327 is a high-power device rated for 33V and 80W, suitable for applications requiring significantly higher power dissipation.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Vce Breakdown (Max) [V]	Power - Max [mW]	Ic (Max) [mA]	hFE (Min) @ Ic, Vce	Operating Temp (TJ) [°C]	Mounting Type	Package	Product Status
BF494_D27Z	onsemi	NPN	20	350	30	67 @ 1mA, 10V	150	Through Hole	TO-92-3	Obsolete
BFP196WH6327XTSA1	Infineon Technologies	NPN	12	700	150	70 @ 50mA, 8V	150	Surface Mount	SOT-343	Active
BFP196WNH6327XTSA1	Infineon Technologies	NPN	12	700	150	70 @ 50mA, 8V	150	Surface Mount	SOT-343	Active
BFQ19SH6327XTSA1	Infineon Technologies	NPN	15	1000	120	70 @ 70mA, 8V	150	Surface Mount	SOT-89	Active
BFR380FH6327XTSA1	Infineon Technologies	NPN	9	380	80	90 @ 40mA, 3V	150	Surface Mount	SOT-723	Active
CMPT918 TR PBFREE	Central Semiconductor Corp	NPN	15	350	50	20 @ 3mA, 1V	150	Surface Mount	SOT-23	Active
MRF327	MACOM Technology Solutions	NPN	33	80000	9000	20 @ 4A, 5V	—	Chassis Mount	316-01	Active

Engineering Selection Recommendations

For Direct Electrical Equivalence: BFP196WH6327XTSA1 and BFP196WNH6327XTSA1 provide the closest electrical performance match to the BF494_D27Z. Both devices are manufactured by Infineon Technologies and maintain active product status with ROHS3 compliance. These parts offer higher power dissipation (700mW versus 350mW) and greater collector current capability (150mA versus 30mA), making them suitable for applications requiring improved thermal and current handling. The primary trade-off is the reduced collector-emitter breakdown voltage (12V versus 20V), which must be evaluated against circuit requirements.

For Voltage-Rated Applications: BFQ19SH6327XTSA1 maintains a 15V collector-emitter breakdown rating closer to the original 20V specification while providing 1W power dissipation. This device is recommended for circuits where voltage margin is critical.

For High-Frequency Applications: BFR380FH6327XTSA1 operates at 14GHz transition frequency with superior noise figure characteristics (1.1dB to 1.6dB at 1.8GHz to 3GHz). This device is suitable for RF applications requiring extended frequency response, though the 9V breakdown voltage represents a significant reduction from the original specification.

For Low-Frequency, Low-Power Applications: CMPT918 TR PBFREE maintains the 350mW power rating and 15V breakdown voltage with active product status and ROHS3 compliance. This device is appropriate for applications not requiring high-frequency performance.

For High-Power Applications: MRF327 is a chassis-mount device rated for 80W power dissipation and 9A collector current. This part is suitable only for applications requiring substantially higher power handling than the original BF494_D27Z.

All substitute parts listed maintain NPN transistor polarity, 150°C maximum junction temperature, and REACH compliance status. Selection should be based on specific circuit voltage, current, frequency, and power requirements.

Frequently Asked Questions (FAQ)

Q: Can BFP196WH6327XTSA1 directly replace BF494_D27Z in existing through-hole designs?

A: No. BFP196WH6327XTSA1 is a surface-mount device in SOT-343 package, while BF494_D27Z uses through-hole TO-92-3 packaging. PCB layout and footprint modifications are required. However, the electrical characteristics are compatible for most RF applications.

Q: What is the primary limitation when substituting BFR380FH6327XTSA1 for BF494_D27Z?

A: BFR380FH6327XTSA1 has a maximum collector-emitter breakdown voltage of 9V, compared to 20V for BF494_D27Z. This device is suitable only for circuits operating at 9V or lower. Applications requiring the full 20V rating must use alternative substitutes such as BFQ19SH6327XTSA1 (15V) or maintain the original part.

Q: Are all substitute parts RoHS compliant?

A: BFP196WH6327XTSA1, BFP196WNH6327XTSA1, BFQ19SH6327XTSA1, BFR380FH6327XTSA1, and CMPT918 TR PBFREE are ROHS3 compliant. MRF327 is ROHS3 compliant. All parts are REACH unaffected.

Q: Which substitute part offers the closest power dissipation match to BF494_D27Z?

A: CMPT918 TR PBFREE matches the 350mW power rating exactly. BFR380FH6327XTSA1 provides 380mW, which is within 8.6% of the original specification. BFP196WH6327XTSA1 and BFP196WNH6327XTSA1 offer 700mW, providing significant thermal margin.

Q: What is the difference between BFP196WH6327XTSA1 and BFP196WNH6327XTSA1?

A: Both devices are electrically identical Infineon BFP196 RF transistors in SOT-343 package. The primary difference is packaging format: BFP196WH6327XTSA1 is supplied in Cut Tape (CT) & Digi-Reel format, while BFP196WNH6327XTSA1 is supplied in Tape & Reel (TR) format. Selection depends on procurement and assembly requirements.

Q: Is MRF327 suitable as a general replacement for BF494_D27Z?

A: No. MRF327 is a high-power chassis-mount device rated for 80W and 9A, designed for power amplifier applications. It is not suitable for low-power RF signal applications. Use MRF327 only when high-power dissipation and current handling are circuit requirements.

Q: What is the DC current gain difference between BF494_D27Z and substitute parts?

A: BF494_D27Z has hFE minimum of 67 at 1mA, 10V. BFP196 devices specify hFE minimum of 70 at 50mA, 8V. BFR380FH6327XTSA1 specifies hFE minimum of 90 at 40mA, 3V. CMPT918 specifies hFE minimum of 20 at 3mA, 1V. Gain characteristics vary with measurement conditions; circuit design must account for these differences.

Q: Can substitute parts be used in existing PCB designs without modification?

A: Surface-mount substitutes (BFP196, BFQ19, BFR380, CMPT918) require PCB redesign due to different package types. Through-hole designs using BF494_D27Z cannot accommodate surface-mount replacements without layout changes. MRF327 requires chassis-mount mechanical integration incompatible with TO-92-3 footprints.

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