S8040R Equivalent & Substitute Parts

Part Overview

The S8040R is a Silicon Controlled Rectifier (SCR) manufactured by Littelfuse Inc., rated for 800V off-state voltage and 40A RMS on-state current in a TO-220-3 through-hole package. This component is discontinued at DiGi Electronics, making equivalent substitute parts necessary for ongoing design support and procurement. The S8040R operates across the industrial temperature range of -40°C to 125°C and is ROHS3 compliant.

Substiute Parts

S8040R

Littelfuse Inc.In Stock: 1075S8040R Datasheet

Current PartRFQ

TYN825RG

STMicroelectronicsIn Stock: 17737TYN825RG Datasheet

MFR RecommendedRFQ

TYN840RG

STMicroelectronicsIn Stock: 1289TYN840RG Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the S8040R is determined by the following critical electrical and mechanical parameters:

• Off-state voltage rating must equal or exceed 800V
• RMS on-state current rating must equal or exceed 40A
• Package type must be TO-220-3 through-hole configuration
• Gate trigger voltage and current must be compatible with circuit design
• Operating temperature range must span -40°C to 125°C
• SCR type must be Standard Recovery

The two substitute parts listed below meet these criteria and are manufactured by STMicroelectronics with active product status.

Parameter Comparison

Engineering Selection Recommendations

TYN840RG is the primary substitute for S8040R. Both devices share identical voltage and current ratings (800V off-state, 40A RMS on-state), matching package configuration (TO-220-3), and operating temperature range (-40°C to 125°C). The TYN840RG is manufactured by STMicroelectronics with active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment.

TYN825RG is a secondary substitute suitable only for applications where the on-state current requirement does not exceed 25A RMS. This device maintains the 800V voltage rating and TO-220-3 package but is limited to 25A RMS current capacity. Selection of TYN825RG requires circuit redesign or thermal management verification to ensure the lower current rating is adequate.

Both substitute parts demonstrate improved electrical characteristics compared to the S8040R, including lower on-state voltage drop (1.6V vs. 1.8V) and reduced off-state leakage current (5µA vs. 20µA).

Frequently Asked Questions (FAQ)

Q: Can TYN840RG directly replace S8040R without circuit modification?

A: Yes. The TYN840RG matches the S8040R in off-state voltage (800V), RMS on-state current (40A), gate trigger specifications, and TO-220-3 package configuration. No circuit modification is required for direct substitution.

Q: Is TYN825RG a suitable replacement for S8040R?

A: TYN825RG is suitable only if the application does not require more than 25A RMS on-state current. The 800V voltage rating and TO-220-3 package are compatible, but the reduced current capacity limits its use to lower-power applications.

Q: What is the difference between the two substitute parts?

A: TYN840RG maintains the full 40A RMS current rating of the S8040R, while TYN825RG is rated for 25A RMS. Both share the same 800V voltage rating, package type, and operating temperature range. TYN840RG is the direct equivalent.

Q: Are the substitute parts ROHS3 compliant?

A: Yes. Both TYN840RG and TYN825RG are ROHS3 compliant, matching the compliance status of the discontinued S8040R.

Q: What is the thermal performance difference between S8040R and TYN840RG?

A: The TYN840RG exhibits lower on-state voltage drop (1.6V vs. 1.8V), resulting in reduced power dissipation and improved thermal performance in equivalent applications.

Q: Are there any gate trigger differences that affect circuit design?

A: Both substitute parts have lower maximum gate trigger voltage (1.3V vs. 1.5V) and comparable gate trigger current specifications. Existing gate drive circuits designed for S8040R will function with the substitutes, as the lower trigger voltage represents improved sensitivity.