IRKT57/12A Equivalent & Substitute Parts

Part Overview

The IRKT57/12A is a dual SCR thyristor module rated for 1.2 kV off-state voltage with 60 A average on-state current and 135 A RMS on-state current. Manufactured by Vishay General Semiconductor - Diodes Division, this component features series-connected SCRs in an ADD-A-PAK (3 + 4) chassis mount package. The product is currently obsolete, making equivalent substitutes necessary for new designs and ongoing system maintenance.

Key Parameters

Parameter	Value
Voltage - Off State	1.2 kV
Current - On State (It (AV)) (Max)	60 A
Current - On State (It (RMS)) (Max)	135 A
Voltage - Gate Trigger (Vgt) (Max)	2.5 V
Current - Gate Trigger (Igt) (Max)	150 mA
Current - Hold (Ih) (Max)	200 mA
Operating Temperature Range	-40°C ~ 125°C (TJ)
Number of SCRs	2 SCRs
Structure	Series Connection - All SCRs
Mounting Type	Chassis Mount

Substitute Part Grouping Explanation

Substitution for the IRKT57/12A is determined by the following critical parameters:

Off-state voltage rating: 1.2 kV (must match exactly)
SCR configuration: Dual series-connected SCRs (must match)
Gate trigger specifications: Vgt (Max) 2.5 V and Igt (Max) 150 mA (must match)
Hold current: 200 mA (Max) (must match)
Operating temperature range: -40°C ~ 125°C (must match)
Mounting type: Chassis mount (must match)

The substitute parts MCC72-12IO1B and MCC95-12IO1B meet all critical substitution criteria. Both are manufactured by IXYS, feature identical voltage ratings, gate trigger specifications, hold current ratings, and operating temperature ranges. Both maintain the dual series-connected SCR configuration and chassis mount design. The primary differences are in on-state current ratings and package format (TO-240AA versus ADD-A-PAK), which represent performance enhancements rather than incompatibilities.

Parameter Comparison

Parameter	IRKT57/12A	MCC72-12IO1B	MCC95-12IO1B
Manufacturer	Vishay General Semiconductor - Diodes Division	IXYS	IXYS
Voltage - Off State	1.2 kV	1.2 kV	1.2 kV
Current - On State (It (AV)) (Max)	60 A	115 A	116 A
Current - On State (It (RMS)) (Max)	135 A	180 A	180 A
Voltage - Gate Trigger (Vgt) (Max)	2.5 V	2.5 V	2.5 V
Current - Gate Trigger (Igt) (Max)	150 mA	150 mA	150 mA
Current - Hold (Ih) (Max)	200 mA	200 mA	200 mA
Operating Temperature	-40°C ~ 125°C (TJ)	-40°C ~ 125°C (TJ)	-40°C ~ 125°C (TJ)
Number of SCRs	2 SCRs	2 SCRs	2 SCRs
Structure	Series Connection - All SCRs	Series Connection - All SCRs	Series Connection - All SCRs
Mounting Type	Chassis Mount	Chassis Mount	Chassis Mount
Package / Case	ADD-A-PAK (3 + 4)	TO-240AA	TO-240AA
Product Status	Obsolete	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Both MCC72-12IO1B and MCC95-12IO1B are suitable substitutes for the obsolete IRKT57/12A based on electrical parameter equivalence. The substitute parts offer the following advantages:

Active product status ensures ongoing availability and supply chain continuity
ROHS3 compliance meets current environmental and regulatory requirements
Enhanced on-state current ratings (115-116 A average, 180 A RMS) provide performance margin beyond the original 60 A average and 135 A RMS specifications
Identical gate trigger and hold current specifications ensure control circuit compatibility
TO-240AA package format is a modern standard for thyristor modules

Package transition from ADD-A-PAK (3 + 4) to TO-240AA requires mechanical redesign of mounting and thermal management interfaces. Both substitute parts maintain identical electrical performance within the specified operating temperature range.

Frequently Asked Questions (FAQ)

Q: Can MCC72-12IO1B and MCC95-12IO1B be used interchangeably with IRKT57/12A?

A: Both parts meet the electrical substitution criteria for IRKT57/12A. The primary consideration is mechanical compatibility. The package change from ADD-A-PAK (3 + 4) to TO-240AA requires modification of the mounting interface and thermal management design.

Q: What is the difference between MCC72-12IO1B and MCC95-12IO1B?

A: Both parts share identical electrical specifications for voltage rating, gate trigger parameters, and operating temperature range. The MCC95-12IO1B features higher non-repetitive surge current ratings (2250A/2400A at 50/60Hz versus 1700A/1800A), providing enhanced transient protection capability.

Q: Are the substitute parts RoHS compliant?

A: Yes. Both MCC72-12IO1B and MCC95-12IO1B are ROHS3 compliant, whereas the original IRKT57/12A is RoHS non-compliant. This compliance status is relevant for applications subject to environmental regulations.

Q: Will the higher on-state current ratings of the substitutes affect circuit operation?

A: No. The substitute parts have higher current ratings (115-116 A average, 180 A RMS) than the original specification (60 A average, 135 A RMS). This represents a performance enhancement that does not affect compatibility in applications designed for the original part.

Q: What are the gate trigger specifications for these parts?

A: All three parts share identical gate trigger specifications: Vgt (Max) 2.5 V and Igt (Max) 150 mA. This ensures control circuit compatibility without modification.

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