BF721T1G Equivalent & Substitute Parts

Part Overview

The BF721T1G is a PNP bipolar junction transistor manufactured by onsemi, housed in a SOT-223 (TO-261) surface mount package. This device is rated for 300 V collector-emitter breakdown voltage with a maximum collector current of 50 mA and 1.5 W power dissipation. The BF721T1G is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain compatibility with the SOT-223 package footprint and satisfy the electrical requirements of the original application.

Key Parameters

Parameter	BF721T1G Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	50	mA
Power - Max	1.5	W
Frequency - Transition	60	MHz
Vce Saturation (Max) @ Ib, Ic	800mV @ 5mA, 30mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	50 @ 25mA, 20V	—
Operating Temperature Range	-65 to 150	°C
Package / Case	TO-261-4, TO-261AA	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the BF721T1G is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Transistor Type: PNP (all substitutes must be PNP)
Package / Case: TO-261-4 or TO-261AA (SOT-223 footprint compatibility)
Mounting Type: Surface Mount
Voltage - Collector Emitter Breakdown (Max): Must equal or exceed 300 V
Current - Collector (Ic) (Max): Must equal or exceed 50 mA

Secondary Compatibility Criteria:

Power - Max: Must equal or exceed 1.5 W
Operating Temperature Range: Must support the application's thermal requirements
RoHS Compliance: ROHS3 Compliant preferred for regulatory alignment

Substitute parts are grouped into two categories based on current handling capability:

Category A - Direct Current Replacement (50 mA to 100 mA): Parts with collector current ratings between 50 mA and 100 mA that maintain the original power and voltage specifications. These parts are suitable for applications where the BF721T1G's 50 mA rating is the design constraint.

Category B - Higher Current Capability (500 mA and above): Parts with collector current ratings of 500 mA or greater. These parts provide enhanced current handling and are suitable for applications requiring higher current capacity while maintaining 300 V voltage rating and SOT-223 package compatibility.

Parameter Comparison

Parameter	BF721T1G	PZTA92T1G	BF723,115	DZTA92-13	FZT757TA	FZT957TA	PZTA92,115
Manufacturer	onsemi	onsemi	Nexperia USA Inc.	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated	Nexperia USA Inc.
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	300 V	300 V	250 V	300 V	300 V	300 V	300 V
Current - Collector (Ic) (Max)	50 mA	500 mA	100 mA	500 mA	500 mA	1 A	100 mA
Power - Max	1.5 W	1.5 W	1.2 W	1 W	2 W	3 W	1.2 W
Frequency - Transition	60 MHz	50 MHz	60 MHz	50 MHz	30 MHz	85 MHz	50 MHz
Vce Saturation (Max) @ Ib, Ic	800mV @ 5mA, 30mA	500mV @ 2mA, 20mA	600mV @ 5mA, 30mA	500mV @ 2mA, 20mA	500mV @ 10mA, 100mA	240mV @ 300mA, 1A	500mV @ 2mA, 20mA
DC Current Gain (hFE) (Min) @ Ic, Vce	50 @ 25mA, 20V	40 @ 30mA, 10V	50 @ 25mA, 20V	25 @ 30mA, 10V	50 @ 100mA, 5V	100 @ 500mA, 10V	25 @ 30mA, 10V
Operating Temperature Range	-65 to 150 °C	150 °C	150 °C	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C	150 °C
Package / Case	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

For Direct Replacement (Minimum Current Requirement):

PZTA92,115 (Nexperia USA Inc.) is the preferred substitute when the application requires a 100 mA collector current rating with 300 V voltage capability. This part maintains ROHS3 compliance, active product status, and AEC-Q101 automotive qualification. The SOT-223 package footprint is identical to the BF721T1G, enabling direct PCB compatibility without layout modifications.

BF723,115 (Nexperia USA Inc.) is an alternative for applications with 250 V voltage tolerance and 100 mA current requirements. This part also carries AEC-Q101 automotive qualification and ROHS3 compliance, with identical package footprint compatibility.

For Enhanced Current Capability:

PZTA92T1G (onsemi) provides 500 mA collector current with 300 V voltage rating and 1.5 W power dissipation, matching the original power specification. Active product status and ROHS3 compliance ensure long-term availability and regulatory alignment.

FZT757TA (Diodes Incorporated) offers 500 mA collector current with 2 W power dissipation and extended operating temperature range (-55°C to 150°C). Active product status supports production continuity.

FZT957TA (Diodes Incorporated) provides the highest current capability at 1 A with 3 W power dissipation, 85 MHz transition frequency, and extended operating temperature range. This part is suitable for applications requiring significant current headroom beyond the original 50 mA specification.

DZTA92-13 (Diodes Incorporated) delivers 500 mA collector current with 300 V voltage rating and extended operating temperature range (-55°C to 150°C). Active product status and ROHS3 compliance support production requirements.

Compliance and Availability:

All recommended substitutes maintain ROHS3 compliance and active product status, ensuring regulatory alignment and long-term supply chain stability. The BF721T1G's obsolete status necessitates transition to one of these active alternatives for new designs and production continuity.

Frequently Asked Questions (FAQ)

Q: Can PZTA92T1G directly replace BF721T1G in existing designs?

A: PZTA92T1G is electrically compatible with BF721T1G for applications operating at or below 50 mA collector current. Both parts share identical 300 V voltage rating, SOT-223 package footprint, and 1.5 W power dissipation. The higher current rating (500 mA) of PZTA92T1G does not affect operation at lower currents. No PCB modifications are required.

Q: What is the voltage difference between BF723,115 and BF721T1G?

A: BF723,115 has a maximum collector-emitter breakdown voltage of 250 V, compared to 300 V for BF721T1G. Applications operating above 250 V require substitutes maintaining the 300 V rating, such as PZTA92T1G, DZTA92-13, FZT757TA, or FZT957TA.

Q: Are all substitute parts available in SOT-223 package?

A: All substitute parts listed are available in TO-261-4 or TO-261AA package variants, which are SOT-223 footprint equivalents. PCB layout compatibility is maintained across all substitutes without requiring design modifications.

Q: Which substitute offers the best thermal performance?

A: FZT957TA provides the highest power dissipation rating at 3 W, followed by FZT757TA at 2 W. Both parts support extended operating temperature range (-55°C to 150°C). Selection depends on application thermal requirements and current demands.

Q: Do all substitutes meet RoHS compliance requirements?

A: All recommended substitutes are ROHS3 compliant. The BF721T1G is also ROHS3 compliant, ensuring regulatory alignment across all alternatives.

Q: What is the difference in saturation voltage between substitutes?

A: Saturation voltage varies across substitutes. FZT957TA exhibits the lowest saturation voltage at 240 mV (@ 300mA, 1A), while BF721T1G shows 800 mV (@ 5mA, 30mA). Lower saturation voltage reduces power dissipation in switching applications. Selection depends on specific circuit requirements and operating point specifications.

Q: Can FZT957TA be used in applications designed for 50 mA operation?

A: FZT957TA is electrically compatible with BF721T1G for 50 mA operation. The 1 A current rating provides significant design margin and does not affect performance at lower currents. The higher power rating (3 W) and improved saturation characteristics may enhance overall circuit performance.

Q: Are there automotive-qualified alternatives available?

A: PZTA92,115 and BF723,115 both carry AEC-Q101 automotive qualification. These parts are suitable for automotive applications requiring qualified component status.

Q: What is the transition frequency difference between substitutes?

A: Transition frequency ranges from 30 MHz (FZT757TA) to 100 MHz (PZTA92E6433HTMA1). Applications with specific frequency requirements should verify substitute specifications against circuit design parameters. BF721T1G operates at 60 MHz.

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