S6040R Equivalent & Substitute Parts

Part Overview

The S6040R is a Silicon Controlled Rectifier (SCR) rated for 600V off-state voltage and 40A RMS on-state current in a TO-220-3 through-hole package. Manufactured by Littelfuse Inc., this thyristor is designed for standard recovery applications requiring high voltage and current handling capability. The product is currently discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives for ongoing system support and new designs.

Key Parameters

Parameter	Value	Unit
Voltage - Off State	600	V
Current - On State (It (RMS))	40	A
Voltage - Gate Trigger (Vgt) (Max)	1.5	V
Current - Gate Trigger (Igt) (Max)	40	mA
Voltage - On State (Vtm) (Max)	1.8	V
Current - Hold (Ih) (Max)	60	mA
Operating Temperature Range	-40 to 125	°C
Package / Case	TO-220-3
SCR Type	Standard Recovery
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitution eligibility for the S6040R is determined by the following critical parameters:

Voltage Rating (Off State): Must be 600V minimum to maintain system voltage protection
Current Rating (RMS): Must support 40A RMS on-state current or higher
Package Type: Must be TO-220-3 through-hole configuration for mechanical and thermal compatibility
SCR Type: Must be Standard Recovery thyristor
Gate Trigger Parameters: Vgt and Igt must be within acceptable control circuit tolerances
Operating Temperature: Must support -40°C to 125°C range
RoHS Compliance: ROHS3 compliance required for regulatory alignment

Two substitute parts meet these criteria with documented parametric equivalence:

SCT640B (SMC Diode Solutions): Matches 600V voltage rating, 40A RMS current, TO-220-3 package, and Standard Recovery type. Gate trigger parameters (Vgt 1.5V max, Igt 35mA max) are compatible. Operating temperature range identical.

TYN625RG (STMicroelectronics): Matches 600V voltage rating and TO-220-3 package with Standard Recovery type. On-state current rating is 25A RMS, which is lower than the primary specification but acceptable for applications not requiring full 40A capacity. Gate trigger parameters (Vgt 1.3V max, Igt 40mA max) are compatible. Operating temperature range identical.

Parameter Comparison

Parameter	S6040R (Littelfuse)	SCT640B (SMC Diode)	TYN625RG (STMicroelectronics)
Voltage - Off State	600 V	600 V	600 V
Voltage - Gate Trigger (Vgt) (Max)	1.5 V	1.5 V	1.3 V
Current - Gate Trigger (Igt) (Max)	40 mA	35 mA	40 mA
Voltage - On State (Vtm) (Max)	1.8 V	1.55 V	1.6 V
Current - On State (It (RMS)) (Max)	40 A	40 A	25 A
Current - Hold (Ih) (Max)	60 mA	75 mA	50 mA
Current - Off State (Max)	10 µA	10 µA	5 µA
Operating Temperature	-40 to 125°C	-40 to 125°C	-40 to 125°C
Package / Case	TO-220-3	TO-220-3	TO-220-3
SCR Type	Standard Recovery	Standard Recovery	Standard Recovery
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

SCT640B Selection: This substitute provides full parametric equivalence to the S6040R across all critical specifications. The 40A RMS current rating matches the original part exactly. Gate trigger voltage and current are within compatible ranges. The part is ROHS3 compliant and maintains identical operating temperature specifications. Product status is listed as Obsolete; however, inventory availability is documented at 2004 pieces. This part is suitable for direct replacement in applications requiring the full 40A capacity.

TYN625RG Selection: This substitute is appropriate for applications where the 25A RMS on-state current rating is sufficient. The 600V voltage rating and TO-220-3 package provide mechanical and electrical compatibility. Gate trigger parameters are favorable (lower Vgt of 1.3V). The part is ROHS3 compliant and currently Active in product status, offering superior long-term availability. Off-state leakage current is lower (5µA vs 10µA), which may provide marginal performance benefits in certain circuit topologies. This part is suitable for applications not requiring the full 40A capacity of the original specification.

Frequently Asked Questions (FAQ)

Q: Can SCT640B be used as a direct drop-in replacement for S6040R?

A: Yes. SCT640B matches the S6040R across all critical parameters: 600V voltage rating, 40A RMS current, TO-220-3 package, Standard Recovery type, and identical operating temperature range. Gate trigger specifications are compatible. Physical pin configuration and thermal characteristics are equivalent.

Q: What is the primary limitation of TYN625RG as a substitute?

A: The TYN625RG has a maximum on-state RMS current rating of 25A, compared to the S6040R specification of 40A. This part is suitable only for applications where the load current does not exceed 25A RMS. All other electrical and mechanical parameters are compatible.

Q: Are both substitute parts RoHS compliant?

A: Yes. Both SCT640B and TYN625RG are ROHS3 compliant, matching the compliance status of the S6040R.

Q: What is the difference in gate trigger voltage between these parts?

A: S6040R and SCT640B both specify a maximum gate trigger voltage (Vgt) of 1.5V. TYN625RG specifies 1.3V maximum, which is lower and may require gate drive circuit adjustment in some applications. Both values are within standard thyristor control circuit tolerances.

Q: Which substitute has better long-term availability?

A: TYN625RG is listed as Active product status, indicating ongoing manufacturing and distribution. SCT640B is listed as Obsolete. For new designs requiring long-term component availability, TYN625RG is the preferred choice if the 25A current rating is acceptable.

Q: Are the thermal characteristics identical between these parts?

A: All three parts share the same TO-220-3 package and -40°C to 125°C operating temperature range. Thermal performance is determined by package design and junction-to-case thermal resistance, which are equivalent across the TO-220-3 standard. Specific thermal resistance values are not provided in the parametric data.

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