FZT491TC Equivalent & Substitute Parts

Part Overview

The FZT491TC is an NPN bipolar junction transistor manufactured by Diodes Incorporated, rated for 60 V collector-emitter breakdown voltage and 1 A maximum collector current in a surface mount SOT-223-3 package. This device is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production continuity. The FZT491TC serves in general-purpose switching and amplification applications requiring moderate voltage and current ratings with compact surface mount packaging.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	1	A
Vce Saturation (Max) @ Ib, Ic	500mV @ 100mA, 1A	—
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 500mA, 5V	—
Power - Max	2	W
Frequency - Transition	150	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-261-4, TO-261AA	—
Supplier Device Package	SOT-223-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FZT491TC is determined by the following critical parameters: NPN transistor type, maximum collector-emitter breakdown voltage of 60 V or greater, maximum collector current of 1 A or greater, surface mount packaging compatibility (SOT-223 or equivalent), and saturation voltage characteristics. Substitute parts are grouped into two categories:

Category 1: Direct Parametric Equivalents Parts that match or exceed all key electrical specifications of the FZT491TC while maintaining identical or compatible package footprints. These parts demonstrate full functional interchangeability.

Category 2: Functional Substitutes with Parameter Variations Parts that satisfy the primary application requirements but exhibit variations in secondary parameters such as transition frequency, power dissipation, or DC current gain. These parts are suitable for applications where the specific parameter variation does not impact circuit performance.

The following parameters determine substitution eligibility:

Transistor Type: NPN (mandatory)
Voltage - Collector Emitter Breakdown: ≥60 V
Current - Collector (Max): ≥1 A
Mounting Type: Surface Mount
Package Compatibility: SOT-223 or TO-261 variants
Vce Saturation: ≤500 mV @ specified test conditions

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) [A]	Vce(br) [V]	Vce Sat (Max) [mV]	hFE (Min)	Power (Max) [W]	Freq - Transition [MHz]	Package
FZT491TC	Diodes Incorporated	Obsolete	1	60	500	100	2	150	SOT-223-3
FZT491TA	Diodes Incorporated	Active	1	60	500	100	2	150	SOT-223-3
2STN1360	STMicroelectronics	Active	3	60	500	160	1.6	130	SOT-223
BCP54,115	Nexperia USA Inc.	Active	1	45	500	63	0.96	180	SOT-223
BCP54,135	Nexperia USA Inc.	Active	1	45	500	63	0.96	180	SOT-223
BCP54-10,135	Nexperia USA Inc.	Active	1	45	500	63	0.65	180	SOT-223
BCP54H6327XTSA1	Infineon Technologies	Last Time Buy	1	45	500	40	2	100	PG-SOT223-4-10
BCP55	onsemi	Active	1.5	60	500	40	1.5	—	SOT-223-4
BCP55,115	Nexperia USA Inc.	Active	1	60	500	63	1.35	180	SOT-223
BCP55,135	Nexperia USA Inc.	Active	1	60	500	63	1.35	180	SOT-223
BCP55-10,115	Nexperia USA Inc.	Active	1	60	500	63	1.35	180	SOT-223

Engineering Selection Recommendations

Primary Recommendation: FZT491TA

The FZT491TA from Diodes Incorporated is the direct parametric equivalent to the FZT491TC. This part maintains identical electrical specifications across all critical parameters: 60 V collector-emitter breakdown voltage, 1 A maximum collector current, 2 W power dissipation, and 150 MHz transition frequency. The FZT491TA is classified as Active product status, ensuring long-term availability and supply chain continuity. Both parts share the same base product number (FZT491) and are packaged in SOT-223-3, providing pin-for-pin compatibility. The FZT491TA is ROHS3 compliant with MSL 1 rating, matching the compliance profile of the obsolete FZT491TC.

Secondary Recommendation: BCP55,115 / BCP55,135 / BCP55-10,115

The BCP55 series from Nexperia USA Inc. provides functional substitution with matched voltage and current ratings. These parts maintain the 60 V collector-emitter breakdown voltage specification and support 1 A collector current, meeting the primary application requirements of the FZT491TC. The BCP55 variants are Active products with high inventory availability. All BCP55 variants are ROHS3 compliant with MSL 1 rating. The primary trade-off is reduced power dissipation (1.35 W versus 2 W) and lower DC current gain (63 versus 100), which are acceptable in applications where these parameters do not constrain circuit design. The BCP55,115 and BCP55,135 variants are available in Tape & Reel packaging, while BCP55-10,115 is available in Cut Tape & Digi-Reel format.

Alternative Recommendation: 2STN1360

The 2STN1360 from STMicroelectronics exceeds the FZT491TC specifications in collector current (3 A versus 1 A) and maintains the 60 V voltage rating. This part is suitable for applications requiring higher current capacity or where design margin is prioritized. The 2STN1360 is classified as Active with strong inventory availability. The transition frequency is reduced to 130 MHz, and power dissipation is 1.6 W. This part is ROHS3 compliant with MSL 1 rating.

Not Recommended: BCP54 Series

The BCP54,115, BCP54,135, and BCP54-10,135 variants from Nexperia USA Inc. feature a reduced collector-emitter breakdown voltage of 45 V, which falls below the 60 V specification of the FZT491TC. These parts are suitable only for applications where the circuit design operates at voltages below 45 V. The BCP54H6327XTSA1 from Infineon Technologies is classified as Last Time Buy, indicating discontinued production and limited future availability.

Frequently Asked Questions (FAQ)

Q: Can the FZT491TA directly replace the FZT491TC without circuit modification?

A: Yes. The FZT491TA is a direct parametric equivalent with identical electrical specifications and pin-compatible SOT-223-3 packaging. No circuit modification is required.

Q: What is the primary reason the FZT491TC is obsolete?

A: The FZT491TC is classified as obsolete by the manufacturer. The FZT491TA serves as the active replacement, maintaining identical specifications and package compatibility.

Q: Can BCP55 series parts replace the FZT491TC in all applications?

A: BCP55 series parts are suitable for applications where the reduced power dissipation (1.35 W versus 2 W) and lower DC current gain (63 versus 100) do not impact circuit performance. The voltage and current ratings are matched. Circuit validation is required for applications with tight thermal or gain requirements.

Q: Why are BCP54 series parts not recommended as substitutes?

A: BCP54 series parts feature a maximum collector-emitter breakdown voltage of 45 V, which is below the 60 V specification of the FZT491TC. These parts are suitable only for circuits designed to operate below 45 V.

Q: What is the difference between BCP55,115, BCP55,135, and BCP55-10,115?

A: These variants are electrically identical with matching specifications. The differences are in packaging format: BCP55,115 and BCP55,135 are supplied in Tape & Reel format, while BCP55-10,115 is supplied in Cut Tape & Digi-Reel format. Selection depends on procurement and assembly requirements.

Q: Is the 2STN1360 a suitable substitute for the FZT491TC?

A: The 2STN1360 is a functional substitute with higher current capacity (3 A versus 1 A) and matched 60 V voltage rating. It is suitable for applications where increased current capability provides design margin. The reduced transition frequency (130 MHz versus 150 MHz) and power dissipation (1.6 W versus 2 W) must be evaluated against circuit requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All recommended substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level, matching the compliance profile of the FZT491TC.

Q: What packaging options are available for substitute parts?

A: All substitute parts are packaged in SOT-223 or compatible variants (SOT-223-3, SOT-223-4, PG-SOT223-4-10). These packages are mechanically and electrically compatible with the FZT491TC footprint. Packaging format options include Cut Tape (CT), Tape & Reel (TR), and Digi-Reel formats depending on the specific part number.

Q: Can the BCP54H6327XTSA1 be used as a long-term substitute?

A: The BCP54H6327XTSA1 is classified as Last Time Buy, indicating discontinued production. This part is not recommended for new designs or long-term production applications due to limited future availability.

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