2N5784 Equivalent & Substitute Parts

Part Overview

The 2N5784 is an NPN bipolar junction transistor (BJT) manufactured by Central Semiconductor Corp, housed in a TO-39 metal can package for through-hole mounting. This device is rated for 65 V collector-emitter breakdown voltage, 3.5 A maximum collector current, and 1 W maximum power dissipation, with an operating temperature range of -65°C to 200°C.

The 2N5784 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure component availability, and support ongoing production and repair requirements for legacy systems utilizing this transistor.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	65	V
Current - Collector (Ic) (Max)	3.5	A
Power - Max	1	W
Vce Saturation (Max) @ Ib, Ic	500mV @ 100mA, 1A	—
DC Current Gain (hFE) (Min) @ Ic, Vce	20 @ 1A, 2V	—
Current - Collector Cutoff (Max)	100	µA
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	TO-39-3 Metal Can	—

Substitute Part Grouping Explanation

Substitution of the 2N5784 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage must equal or exceed 65 V
Maximum collector current must equal or exceed 3.5 A
Maximum power dissipation must equal or exceed 1 W
Operating temperature range must encompass -65°C to 200°C
DC current gain characteristics must support the intended application

Mechanical Compatibility Criteria:

Package type must be TO-39 metal can (TO-205AD)
Through-hole mounting configuration

The 2N3421S meets these substitution criteria. It provides higher voltage rating (80 V), slightly lower maximum collector current (3 A), equivalent power rating (1 W), matching temperature range, and identical package configuration. The 2N3421S is an active product with current manufacturing support, addressing the obsolescence status of the 2N5784.

Parameter Comparison

Parameter	2N5784	2N3421S	Unit
Manufacturer	Central Semiconductor Corp	Microchip Technology	—
Product Status	Obsolete	Active	—
Transistor Type	NPN	NPN	—
Voltage - Collector Emitter Breakdown (Max)	65	80	V
Current - Collector (Ic) (Max)	3.5	3	A
Power - Max	1	1	W
Vce Saturation (Max) @ Ib, Ic	500mV @ 100mA, 1A	500mV @ 200mA, 2A	—
Current - Collector Cutoff (Max)	100	5	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	20 @ 1A, 2V	40 @ 1A, 2V	—
Operating Temperature Range	-65 to 200	-65 to 200	°C
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-39-3 Metal Can	TO-39-3 Metal Can	—

Engineering Selection Recommendations

2N3421S as Primary Substitute:

The 2N3421S is the appropriate substitute for the obsolete 2N5784. This selection is based on the following factors:

Product Status: The 2N3421S maintains active manufacturing status through Microchip Technology, ensuring long-term availability and supply chain continuity.
Electrical Compatibility: The 2N3421S exceeds the voltage rating requirement (80 V vs. 65 V), providing design margin. The maximum collector current of 3 A is within 86% of the 2N5784 specification (3.5 A), suitable for applications not requiring the full 3.5 A rating.
Package Compatibility: Both devices utilize identical TO-39 metal can packaging, enabling direct mechanical substitution without circuit board redesign.
Temperature Range: Operating temperature specifications are identical, supporting equivalent thermal performance across the full operating envelope.
Compliance: The 2N3421S carries REACH Unaffected and EAR99 ECCN classifications, matching the regulatory profile of the original part.

Applications requiring the full 3.5 A collector current specification of the 2N5784 require evaluation of alternative NPN transistors with higher current ratings in compatible packages.

Frequently Asked Questions (FAQ)

Q: Can the 2N3421S directly replace the 2N5784 in all applications?

A: The 2N3421S is mechanically and electrically compatible for applications where the collector current requirement does not exceed 3 A. The 2N5784 is rated for 3.5 A maximum collector current, while the 2N3421S is rated for 3 A. Applications operating at collector currents between 3 A and 3.5 A require design review to confirm the 2N3421S operates within acceptable thermal and electrical margins.

Q: What are the key differences between the 2N5784 and 2N3421S?

A: The 2N3421S provides a higher collector-emitter breakdown voltage (80 V vs. 65 V), lower maximum collector current (3 A vs. 3.5 A), lower collector cutoff current (5 µA vs. 100 µA), and higher DC current gain (40 vs. 20 at 1 A, 2 V). Both devices share identical power ratings, temperature ranges, and TO-39 packaging.

Q: Are there any compliance or certification differences?

A: Both the 2N5784 and 2N3421S carry identical REACH Unaffected and EAR99 ECCN classifications. The 2N3421S is RoHS non-compliant, which should be verified against specific application requirements.

Q: Will the 2N3421S fit the same circuit board footprint as the 2N5784?

A: Yes. Both devices use TO-39 metal can packaging with identical pin configurations and through-hole mounting requirements. No circuit board modifications are necessary for mechanical substitution.

Q: What should be considered when substituting the 2N5784 with the 2N3421S?

A: Verify that the application collector current requirement does not exceed 3 A. Confirm that the higher DC current gain (40 vs. 20) does not adversely affect circuit biasing or frequency response. Validate that the lower collector cutoff current (5 µA vs. 100 µA) is acceptable for the intended application. Review RoHS compliance requirements if applicable to the end product.

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