S8025R Equivalent & Substitute Parts

Part Overview

The S8025R is a silicon-controlled rectifier (SCR) manufactured by Littelfuse Inc., rated for 800V off-state voltage and 25A 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.

Key Parameters

Parameter	Value
Voltage - Off State	800 V
Current - On State (It (RMS)) (Max)	25 A
Voltage - Gate Trigger (Vgt) (Max)	1.5 V
Current - Gate Trigger (Igt) (Max)	35 mA
Voltage - On State (Vtm) (Max)	1.6 V
SCR Type	Standard Recovery
Operating Temperature	-40°C ~ 125°C
Package / Case	TO-220-3
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the S8025R is determined by the following criteria:

Off-state voltage rating of 800V
RMS on-state current rating of 25A or higher
Standard Recovery SCR type
TO-220-3 package compatibility
Operating temperature range of -40°C to 125°C
ROHS3 compliance

The substitute parts listed below meet these core electrical and mechanical requirements. Parts are grouped by product status and availability to support design continuity.

Parameter Comparison

Parameter	S8025R (Littelfuse)	BT145-800R,127 (WeEn)	SCT825B (SMC Diode)	TYN825RG (STMicro)	TYN840RG (STMicro)
Voltage - Off State	800 V	800 V	800 V	800 V	800 V
Current - On State (It (RMS)) (Max)	25 A	25 A	25 A	25 A	40 A
Voltage - Gate Trigger (Vgt) (Max)	1.5 V	1 V	1.3 V	1.3 V	1.3 V
Current - Gate Trigger (Igt) (Max)	35 mA	35 mA	40 mA	40 mA	35 mA
Voltage - On State (Vtm) (Max)	1.6 V	1.5 V	1.55 V	1.6 V	1.6 V
Current - Hold (Ih) (Max)	50 mA	60 mA	80 mA	50 mA	75 mA
Current - Off State (Max)	20 µA	1 mA	10 µA	5 µA	5 µA
SCR Type	Standard Recovery	Standard Recovery	Standard Recovery	Standard Recovery	Standard Recovery
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C (TJ)	-40°C ~ 125°C	-40°C ~ 125°C
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Discontinued	Active	Obsolete	Active	Active

Engineering Selection Recommendations

For new designs and ongoing procurement, the following substitutes are recommended based on product status and compliance:

Primary Substitutes (Active Status):

BT145-800R,127 (WeEn Semiconductors): Active product with full ROHS3 compliance and REACH affected status. Gate trigger voltage is lower (1V max) than the original, providing improved gate sensitivity.
TYN825RG (STMicroelectronics): Active product with ROHS3 compliance and REACH unaffected status. Electrical parameters closely match the S8025R with identical RMS current rating.
TYN840RG (STMicroelectronics): Active product with ROHS3 compliance and REACH unaffected status. Rated for 40A RMS on-state current, providing higher current capability than the original 25A rating.

Secondary Substitute (Obsolete Status):

SCT825B (SMC Diode Solutions): Obsolete product with ROHS3 compliance and REACH affected status. Not recommended for new designs due to discontinued status.

Frequently Asked Questions (FAQ)

Q: Can TYN840RG be used as a direct replacement for S8025R? A: TYN840RG meets all core substitution criteria including 800V off-state voltage, TO-220-3 package, and Standard Recovery type. The 40A RMS current rating exceeds the 25A requirement, making it electrically compatible. However, verify circuit design does not depend on the lower current rating of the original part.

Q: What is the difference between TO-220AB and TO-220C package variants? A: Both are TO-220-3 packages with identical pin configurations and mechanical compatibility. TO-220AB and TO-220C refer to supplier-specific package designations. All listed substitutes are mechanically interchangeable in TO-220-3 footprints.

Q: Are there differences in gate trigger characteristics between substitutes? A: Yes. BT145-800R,127 has the lowest gate trigger voltage (1V max), while SCT825B and the TYN series have 1.3V max. The original S8025R specifies 1.5V max. Lower gate trigger voltage may require circuit verification to ensure gate drive circuits remain compatible.

Q: Which substitute has the best long-term availability? A: TYN825RG and TYN840RG from STMicroelectronics are both active products with REACH unaffected status, indicating stable long-term availability. BT145-800R,127 is also active but carries REACH affected status.

Q: Is the S8025R substitute selection affected by REACH compliance requirements? A: REACH status varies among substitutes. TYN825RG and TYN840RG are REACH unaffected. BT145-800R,127 and SCT825B are REACH affected. Verify your supply chain and end-market requirements before final selection.

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