2N681 Equivalent & Substitute Parts

Part Overview

The 2N681 is a standard recovery SCR (silicon-controlled rectifier) rated for 25V off-state voltage and 25A RMS on-state current in a TO-48 chassis mount stud package. Manufactured by Central Semiconductor Corp, this component is classified as obsolete. Due to its obsolete status and limited availability from the original manufacturer, identifying equivalent substitute parts is necessary to maintain design continuity and ensure supply chain reliability for applications requiring this thyristor specification.

Key Parameters

Parameter	Value
Voltage - Off State	25 V
Voltage - Gate Trigger (Vgt) (Max)	2 V
Current - Gate Trigger (Igt) (Max)	40 mA
Voltage - On State (Vtm) (Max)	2 V
Current - On State (It (RMS)) (Max)	25 A
Current - Hold (Ih) (Max)	100 mA
Current - Off State (Max)	13 mA
Current - Non Rep. Surge 50, 60Hz (Itsm)	200 A @ 60Hz
SCR Type	Standard Recovery
Operating Temperature Range	-65°C to 125°C
Mounting Type	Chassis, Stud Mount
Package / Case	TO-208AA, TO-48-3, Stud

Substitute Part Grouping Explanation

Substitution of the 2N681 is determined by electrical and mechanical parameter equivalence within the thyristor category. The critical parameters governing substitutability are:

Off-state voltage rating (25 V minimum)
RMS on-state current capability (25 A minimum)
Gate trigger voltage and current specifications (Vgt ≤ 2 V, Igt ≤ 40 mA)
On-state voltage drop (Vtm ≤ 2 V)
Hold current specification (Ih ≤ 100 mA)
SCR type classification (Standard Recovery)
Mounting configuration (Chassis, Stud Mount)
Package compatibility (TO-208AA / TO-48 equivalent)

The VS-2N681 manufactured by Vishay General Semiconductor meets these electrical specifications and maintains mechanical compatibility through equivalent package designation (TO-208AA is the standardized equivalent to TO-48).

Parameter Comparison

Parameter	2N681 (Central Semiconductor)	VS-2N681 (Vishay)
Voltage - Off State	25 V	25 V
Voltage - Gate Trigger (Vgt) (Max)	2 V	2 V
Current - Gate Trigger (Igt) (Max)	40 mA	40 mA
Voltage - On State (Vtm) (Max)	2 V	2 V
Current - On State (It (RMS)) (Max)	25 A	25 A
Current - Hold (Ih) (Max)	100 mA	20 mA
Current - Off State (Max)	13 mA	6.5 mA
SCR Type	Standard Recovery	Standard Recovery
Operating Temperature Range	-65°C to 125°C	-65°C to 125°C
Mounting Type	Chassis, Stud Mount	Chassis, Stud Mount
Package / Case	TO-208AA, TO-48-3, Stud	TO-208AA, TO-48-3, Stud
Product Status	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

The VS-2N681 is the direct manufacturer-recommended substitute for the obsolete 2N681. Selection of this substitute is justified on the following basis:

Electrical equivalence is established across all primary thyristor parameters: off-state voltage, gate trigger specifications, on-state voltage, and RMS current rating. The VS-2N681 demonstrates improved performance characteristics with lower hold current (20 mA vs. 100 mA) and reduced off-state leakage current (6.5 mA vs. 13 mA), which may provide operational advantages in power control applications.

Product status transition from obsolete to active ensures long-term supply availability and manufacturing continuity. The VS-2N681 carries ROHS3 compliance certification, addressing regulatory requirements for new designs and procurement cycles. Mechanical compatibility is maintained through equivalent TO-208AA package designation and identical stud mount configuration.

Frequently Asked Questions (FAQ)

Q: Can the VS-2N681 be used as a direct replacement for the 2N681 in existing designs?

A: Yes. The VS-2N681 meets all electrical specifications of the 2N681 across voltage ratings, current ratings, and gate trigger parameters. Mechanical compatibility is maintained through equivalent package designation and stud mount configuration. No circuit modifications are required.

Q: What is the difference between TO-48 and TO-208AA package designations?

A: TO-208AA is the standardized package designation for the same physical form factor previously designated as TO-48. Both designations refer to identical three-lead stud mount packages with equivalent mechanical and thermal characteristics.

Q: Are there differences in performance between the 2N681 and VS-2N681?

A: The VS-2N681 exhibits lower hold current (20 mA vs. 100 mA) and reduced off-state leakage current (6.5 mA vs. 13 mA). These represent improved performance characteristics that do not affect substitutability but may provide operational benefits in power control applications.

Q: What is the significance of RoHS compliance for the VS-2N681?

A: ROHS3 compliance indicates the VS-2N681 meets current regulatory requirements for hazardous substance restrictions. This is relevant for new designs, procurement cycles, and applications subject to environmental compliance mandates. The original 2N681 is RoHS non-compliant.

Q: Is the VS-2N681 available in the same packaging options as the 2N681?

A: Yes. The VS-2N681 is supplied in bulk packaging and maintains the same TO-208AA (TO-48) stud mount configuration as the original 2N681, ensuring mechanical and thermal compatibility in existing mounting arrangements.

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