BFQ31ATC Equivalent & Substitute Parts

Part Overview

The BFQ31ATC is an RF transistor NPN manufactured by Diodes Incorporated, designed for radio frequency applications requiring 15V collector-emitter breakdown voltage and 600MHz transition frequency. This device is packaged in SOT-23-3 surface mount configuration with 330mW maximum power dissipation and 100mA maximum collector current. The BFQ31ATC is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	15V	V
Frequency - Transition	600MHz	MHz
Noise Figure (Typ @ f)	6dB @ 60MHz	dB
Power - Max	330mW	mW
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 3mA, 1V	—
Current - Collector (Ic) (Max)	100mA	mA
Operating Temperature	-55°C ~ 150°C	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the BFQ31ATC is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown (Max): Must equal or exceed 15V
Frequency - Transition: Must equal or exceed 600MHz
Package / Case: SOT-23-3 compatible packages (TO-236-3, SC-59, SOT-23-3)
Mounting Type: Surface Mount (required match)

Secondary Compatibility Factors:

Power - Max: Must equal or exceed 330mW
Current - Collector (Ic) (Max): Must equal or exceed 100mA
Operating Temperature Range: Must encompass or extend the -55°C ~ 150°C range
RoHS and MSL Compliance: Must maintain ROHS3 Compliant and MSL 1 status

Substitute parts are grouped into two categories:

Category A - Direct Package Equivalents (SOT-23-3): Parts maintaining the identical SOT-23-3 package form factor with electrical parameters meeting or exceeding the BFQ31ATC specifications. These parts provide direct mechanical and electrical compatibility.

Category B - Enhanced Performance Alternatives (SOT-343 and SOT-89): Parts with superior frequency response, power handling, or current capability packaged in alternative surface mount configurations. These require PCB layout modification but offer improved performance margins for RF applications.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Vce Breakdown (Max)	Frequency - Transition	Power - Max	Ic (Max)	Package / Case	Product Status
BFQ31ATC	Diodes Incorporated	NPN	15V	600MHz	330mW	100mA	SOT-23-3	Obsolete
BFR35APE6327HTSA1	Infineon Technologies	NPN	15V	5GHz	280mW	45mA	SOT-23-3	Active
BFU520AR	NXP USA Inc.	NPN	12V	10GHz	450mW	30mA	SOT-23-3	Active
BFU520AVL	NXP USA Inc.	NPN	12V	10GHz	450mW	30mA	SOT-23-3	Active
BFU530AR	NXP USA Inc.	NPN	12V	11GHz	450mW	40mA	SOT-23-3	Active
BFU530AVL	NXP USA Inc.	NPN	12V	11GHz	450mW	40mA	SOT-23-3	Active
BFQ19SH6327XTSA1	Infineon Technologies	NPN	15V	5.5GHz	1W	120mA	SOT-89-3	Active
BFP196WH6327XTSA1	Infineon Technologies	NPN	12V	7.5GHz	700mW	150mA	SOT-343	Active
BFP450H6433XTMA1	Infineon Technologies	NPN	5V	24GHz	450mW	100mA	SOT-343	Active
BFP620H7764XTSA1	Infineon Technologies	NPN	2.8V	65GHz	185mW	80mA	SOT-343	Active
BFP650H6327XTSA1	Infineon Technologies	NPN	4.5V	37GHz	500mW	150mA	SOT-343	Active

Engineering Selection Recommendations

Direct Replacement (Same Package - SOT-23-3):

BFR35APE6327HTSA1 (Infineon Technologies) is the primary direct replacement for the BFQ31ATC. This part maintains identical 15V collector-emitter breakdown voltage and SOT-23-3 package configuration. The BFR35APE6327HTSA1 exceeds the BFQ31ATC in transition frequency (5GHz vs. 600MHz) and provides active product status with ROHS3 compliance and MSL 1 rating. However, the maximum collector current is reduced to 45mA and power dissipation to 280mW, requiring circuit verification for current and power requirements.

BFU520AR and BFU520AVL (NXP USA Inc.) are active SOT-23-3 packaged alternatives with 10GHz transition frequency and 450mW power handling. These parts operate at 12V collector-emitter breakdown, which is below the BFQ31ATC specification of 15V. Both variants maintain ROHS3 compliance and MSL 1 rating. The BFU520AR includes AEC-Q101 automotive qualification. Maximum collector current is 30mA, requiring circuit redesign for higher current applications.

BFU530AR and BFU530AVL (NXP USA Inc.) provide 11GHz transition frequency in SOT-23-3 packaging with 450mW power dissipation and 40mA maximum collector current. These parts also operate at 12V collector-emitter breakdown. Both maintain ROHS3 compliance and MSL 1 rating, with BFU530AR including AEC-Q101 automotive qualification.

Enhanced Performance Alternatives (Alternative Packages):

BFQ19SH6327XTSA1 (Infineon Technologies) maintains the 15V collector-emitter breakdown voltage specification and provides superior power handling (1W vs. 330mW) and current capability (120mA vs. 100mA). This part is packaged in SOT-89-3, requiring PCB layout modification. Transition frequency is 5.5GHz, exceeding the BFQ31ATC requirement. ROHS3 compliance and MSL 1 rating are maintained.

BFP196WH6327XTSA1 (Infineon Technologies) operates at 12V collector-emitter breakdown in SOT-343 packaging with 7.5GHz transition frequency, 700mW power dissipation, and 150mA maximum collector current. This part requires PCB layout modification due to package change.

BFP450H6433XTMA1 (Infineon Technologies) provides 24GHz transition frequency in SOT-343 packaging but operates at only 5V collector-emitter breakdown, significantly below the BFQ31ATC specification. This part is suitable only for applications with reduced voltage requirements.

BFP620H7764XTSA1 (Infineon Technologies) offers 65GHz transition frequency in SOT-343 packaging but operates at 2.8V collector-emitter breakdown and provides only 185mW power dissipation. This part is suitable only for ultra-high-frequency, low-voltage applications.

BFP650H6327XTSA1 (Infineon Technologies) provides 37GHz transition frequency in SOT-343 packaging with 500mW power dissipation and 150mA maximum collector current. This part operates at 4.5V collector-emitter breakdown, below the BFQ31ATC specification.

Compliance and Certification Status:

All recommended substitute parts maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, consistent with the BFQ31ATC. All parts are classified as Active product status, ensuring long-term availability and supply chain continuity. NXP USA Inc. variants BFU520AR and BFU530AR include AEC-Q101 automotive qualification, suitable for automotive RF applications.

Frequently Asked Questions (FAQ)

Q: Can BFR35APE6327HTSA1 be used as a direct replacement for BFQ31ATC?

A: BFR35APE6327HTSA1 is compatible in package (SOT-23-3) and maintains the 15V collector-emitter breakdown voltage. However, maximum collector current is reduced from 100mA to 45mA, and power dissipation is reduced from 330mW to 280mW. Circuit verification is required to confirm that application current and power requirements do not exceed these limits.

Q: What is the primary difference between BFU520AR and BFU520AVL?

A: Both parts are electrically identical NPN RF transistors with 12V collector-emitter breakdown, 10GHz transition frequency, 450mW power dissipation, and 30mA maximum collector current in SOT-23-3 packaging. BFU520AR includes AEC-Q101 automotive qualification. Selection depends on application requirements for automotive-grade certification.

Q: Why do some substitute parts have lower collector-emitter breakdown voltage than the BFQ31ATC?

A: BFU520AR, BFU520AVL, BFU530AR, and BFU530AVL operate at 12V collector-emitter breakdown, which is below the BFQ31ATC specification of 15V. These parts are suitable only for applications where the maximum supply voltage does not exceed 12V. Applications requiring 15V operation must use BFR35APE6327HTSA1 or BFQ19SH6327XTSA1.

Q: What package modifications are required when using BFQ19SH6327XTSA1 instead of BFQ31ATC?

A: BFQ19SH6327XTSA1 is packaged in SOT-89-3 (TO-243AA), which has a different pin configuration and footprint than the SOT-23-3 package of BFQ31ATC. PCB layout modification is required, including new pad design and trace routing. Pin assignment must be verified against device datasheets before implementation.

Q: Are all substitute parts RoHS compliant?

A: All substitute parts listed are ROHS3 compliant and maintain MSL 1 (Unlimited) moisture sensitivity rating, consistent with the BFQ31ATC. This ensures compliance with environmental and regulatory requirements for lead-free manufacturing and hazardous substance restrictions.

Q: Which substitute part provides the best frequency performance?

A: BFP620H7764XTSA1 provides the highest transition frequency at 65GHz, followed by BFP650H6327XTSA1 at 37GHz, and BFP450H6433XTMA1 at 24GHz. However, these parts operate at significantly reduced collector-emitter breakdown voltages (2.8V, 4.5V, and 5V respectively) compared to the BFQ31ATC specification of 15V. Selection must balance frequency requirements against voltage specifications for the target application.

Q: Can BFP620H7764XTSA1 be used in a 15V application?

A: No. BFP620H7764XTSA1 has a maximum collector-emitter breakdown voltage of 2.8V and cannot be used in applications requiring 15V operation. Using this part in a 15V circuit will result in device failure due to voltage overstress.

Q: What is the difference between Cut Tape (CT) and Tape & Reel (TR) packaging?

A: Cut Tape (CT) and Digi-Reel® packaging provides components in individual strips suitable for manual assembly or small-volume production. Tape & Reel (TR) packaging provides components on continuous reels suitable for automated assembly equipment. Both packaging formats contain identical components; selection depends on assembly process requirements.

Q: Is BFU530AR suitable for automotive applications?

A: Yes. BFU530AR includes AEC-Q101 automotive qualification, indicating compliance with automotive industry reliability and quality standards. This part is suitable for automotive RF applications requiring 12V operation, 11GHz transition frequency, and SOT-23-3 packaging.

Q: What is the operating temperature range for all substitute parts?

A: All substitute parts operate across -40°C to 150°C (TJ) or -55°C to 150°C (TJ) junction temperature ranges, meeting or exceeding the BFQ31ATC specification of -55°C to 150°C. Specific operating temperature ranges are provided in individual part datasheets.

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