12TTS08 SCR Thyristor Equivalent & Substitute Parts

Part Overview

The 12TTS08 is an 800V, 12.5A standard recovery silicon controlled rectifier (SCR) manufactured by Vishay General Semiconductor - Diodes Division in TO-220-3 package configuration. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system maintenance and new design implementations. The part operates across a temperature range of -40°C to 125°C and is designed for through-hole mounting applications requiring high-voltage switching capability.

Substiute Parts

12TTS08

Vishay General Semiconductor - Diodes DivisionIn Stock: 218012TTS08 Datasheet

Current PartRFQ

VS-12TTS08-M3

Vishay General Semiconductor - Diodes DivisionIn Stock: 1442VS-12TTS08-M3 Datasheet

Parametric EquivalentRFQ

SCT812B

SMC Diode SolutionsIn Stock: 1337SCT812B Datasheet

MFR RecommendedRFQ

TYN812RG

STMicroelectronicsIn Stock: 26265TYN812RG Datasheet

MFR RecommendedRFQ

TYN812TRG

STMicroelectronicsIn Stock: 1337TYN812TRG Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 12TTS08 is determined by the following critical parameters:

• Voltage Rating (Off State): 800V minimum required
• Current Rating (RMS): 12.5A or higher
• Gate Trigger Voltage (Vgt): Maximum 1V
• Gate Trigger Current (Igt): Maximum 15mA
• On-State Voltage (Vtm): Maximum 1.2V
• Hold Current (Ih): Maximum 30mA
• Package Configuration: TO-220-3 through-hole mounting
• SCR Type: Standard Recovery

Substitute parts must meet or exceed these specifications to ensure functional compatibility in existing circuit designs. Parts are grouped based on their adherence to these electrical and mechanical constraints.

Parameter Comparison

Engineering Selection Recommendations

VS-12TTS08-M3 (Vishay) provides the closest electrical match to the 12TTS08, with identical gate trigger voltage (1V maximum) and on-state voltage (1.2V maximum) specifications. This part is currently in active production status with ROHS3 compliance certification, making it the preferred direct replacement for new procurement and system redesigns. The primary trade-off is reduced non-repetitive surge current (95A versus 140A), which may require circuit evaluation in high-surge applications.

TYN812RG and TYN812TRG (STMicroelectronics) are active production alternatives with 800V rating and 12A RMS current capability. Both parts exhibit higher gate trigger voltage (1.3V) and on-state voltage (1.6V) compared to the original specification. TYN812TRG offers reduced gate trigger current (5mA) and hold current (15mA), providing improved gate drive efficiency. Both variants maintain ROHS3 compliance and demonstrate superior off-state leakage characteristics (5µA versus 50µA).

SCT812B (SMC Diode Solutions) meets the 800V and 12A current requirements with extended operating temperature range (-40°C to 150°C). This part carries ROHS3 compliance but is classified as obsolete. Gate trigger voltage (1.5V maximum) and on-state voltage (1.55V maximum) exceed original specifications, and hold current (50mA maximum) is elevated relative to the 12TTS08.

For new designs requiring long-term component availability, select from active production alternatives: VS-12TTS08-M3 for closest electrical equivalence, or TYN812RG/TYN812TRG for enhanced performance characteristics and superior inventory availability.

Frequently Asked Questions (FAQ)

Q: Can VS-12TTS08-M3 be used as a direct replacement for 12TTS08 in existing designs?

A: Yes. VS-12TTS08-M3 matches the critical electrical parameters: 800V off-state voltage, 1V maximum gate trigger voltage, 1.2V maximum on-state voltage, and 12.5A RMS current rating. Both use TO-220-3 package configuration. The reduced non-repetitive surge current (95A versus 140A) requires verification only in circuits designed to exploit the original 140A surge capability.

Q: What are the key differences between TYN812RG and TYN812TRG?

A: Both parts share identical voltage ratings (800V), current ratings (12A RMS), and package configuration (TO-220-3). TYN812TRG provides lower gate trigger current (5mA maximum versus 15mA) and reduced hold current (15mA maximum versus 30mA), resulting in improved gate drive efficiency. Selection depends on gate drive circuit design requirements.

Q: Are all substitute parts ROHS3 compliant?

A: VS-12TTS08-M3, TYN812RG, TYN812TRG, and SCT812B are all ROHS3 compliant. The original 12TTS08 is RoHS non-compliant. For applications requiring RoHS compliance certification, any of the four substitute parts satisfy regulatory requirements.

Q: What is the impact of higher gate trigger voltage in TYN812RG and TYN812TRG?

A: Gate trigger voltage of 1.3V (versus 1V in the original) requires slightly higher gate drive voltage to ensure reliable triggering. Existing gate drive circuits designed for 1V triggering will function with these parts but may operate with reduced gate drive margin. Circuit simulation or testing is appropriate for margin-critical applications.

Q: Can SCT812B be used in new designs?

A: SCT812B is classified as obsolete and carries REACH-affected status. While electrically functional as a substitute, long-term availability cannot be assured. For new designs, select from active production alternatives: VS-12TTS08-M3, TYN812RG, or TYN812TRG.

Q: How do off-state leakage currents compare across substitute options?

A: The original 12TTS08 specifies 50µA maximum off-state current. VS-12TTS08-M3 maintains this specification. TYN812RG, TYN812TRG, and SCT812B all specify 5µA maximum, representing a 10-fold improvement in leakage performance. Lower leakage reduces standby power dissipation in applications with extended off-state periods.