ACST12-7ST TRIAC Equivalent & Substitute Parts

Part Overview

The ACST12-7ST is a Logic-Sensitive Gate TRIAC manufactured by STMicroelectronics, rated for 700 V off-state voltage and 12 A on-state current in a Through Hole TO-220-3 package. This component is classified as Obsolete product status. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support legacy system maintenance where this TRIAC is specified in active applications.

Substiute Parts

ACST12-7ST

STMicroelectronicsIn Stock: 1112ACST12-7ST Datasheet

Current PartRFQ

BTA12-700SWRG

STMicroelectronicsIn Stock: 2192BTA12-700SWRG Datasheet

SimilarRFQ

ACST12-7ST

STMicroelectronicsIn Stock: 1112ACST12-7ST Datasheet

Parametric EquivalentRFQ

ACST1210-7T

STMicroelectronicsIn Stock: 1527ACST1210-7T Datasheet

Parametric EquivalentRFQ

BTA312-800E,127

WeEn SemiconductorsIn Stock: 698BTA312-800E,127 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the ACST12-7ST TRIAC is determined by the following critical parameters:

Primary Substitution Criteria:

• Voltage - Off State: 700 V minimum (higher voltage ratings acceptable)
• Current - On State (It (RMS)) (Max): 12 A minimum
• Triac Type: Logic - Sensitive Gate
• Package / Case: TO-220-3
• Mounting Type: Through Hole
• Gate Trigger Voltage (Vgt): 1 V to 1.5 V range
• Gate Trigger Current (Igt): 10 mA maximum
• Operating Temperature: -40°C minimum to 110°C minimum

Substitute Parts Identified:

1. BTA12-700SWRG (STMicroelectronics) - Direct parametric equivalent with active product status
2. ACST1210-7T (STMicroelectronics) - Parametric equivalent with identical electrical specifications
3. BTA312-800E,127 (WeEn Semiconductors) - Higher voltage rating (800 V) with compatible current and gate specifications

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: BTA12-700SWRG

The BTA12-700SWRG is the preferred substitute for the obsolete ACST12-7ST. This part maintains identical voltage and current ratings (700 V, 12 A), matching gate trigger current specifications (10 mA maximum), and is manufactured by the same supplier (STMicroelectronics). The BTA12-700SWRG holds Active product status, ensuring long-term availability and supply chain continuity. Both parts are ROHS3 Compliant with MSL 1 (Unlimited) moisture sensitivity rating. The gate trigger voltage (Vgt) is slightly elevated at 1.3 V compared to 1 V, and the hold current (Ih) is reduced to 15 mA from 30 mA, representing acceptable parameter variations within the Logic-Sensitive Gate TRIAC classification. Operating temperature range is reduced to -40°C to 110°C, which is acceptable for most applications not requiring the full 125°C upper limit.

Secondary Recommendation: ACST1210-7T

The ACST1210-7T provides an exact parametric match to the ACST12-7ST, with identical electrical specifications including gate trigger voltage (1 V), hold current (30 mA), and operating temperature range (-40°C to 125°C). However, this part also carries Obsolete product status. The ACST1210-7T is suitable for applications where exact parameter matching is critical and where supply from existing inventory is available. This part is manufactured by STMicroelectronics and maintains ROHS3 Compliance.

Alternative Recommendation: BTA312-800E,127

The BTA312-800E,127 offers a higher voltage rating (800 V) with compatible current specifications (12 A). This part is manufactured by WeEn Semiconductors and maintains Active product status, providing superior long-term availability. The elevated voltage rating provides additional design margin in applications where voltage stress is a concern. Gate trigger specifications remain compatible (10 mA maximum). The non-repetitive surge current rating is reduced (95A, 126A versus 120A, 126A), and hold current is reduced to 15 mA. This part is suitable for applications where higher voltage headroom is beneficial and where the reduced surge current rating does not impact system performance.

Frequently Asked Questions (FAQ)

Q: Can the BTA12-700SWRG directly replace the ACST12-7ST without circuit modifications?

A: The BTA12-700SWRG is a direct functional replacement for the ACST12-7ST in the TO-220-3 package. Both parts share identical voltage (700 V) and current (12 A) ratings, gate trigger current (10 mA), and configuration (Single, Logic-Sensitive Gate). The gate trigger voltage is slightly higher (1.3 V versus 1 V) and hold current is lower (15 mA versus 30 mA), which are acceptable variations within TRIAC specifications. No circuit modifications are required.

Q: What is the difference between the ACST12-7ST and ACST1210-7T?

A: The ACST1210-7T provides identical electrical specifications to the ACST12-7ST, including gate trigger voltage (1 V), hold current (30 mA), and operating temperature range (-40°C to 125°C). Both parts are obsolete. The primary difference is packaging: ACST12-7ST is supplied without specified packaging, while ACST1210-7T is supplied in Tube packaging. Both are manufactured by STMicroelectronics and are ROHS3 Compliant.

Q: Why would I choose the BTA312-800E,127 over the BTA12-700SWRG?

A: The BTA312-800E,127 provides a higher off-state voltage rating (800 V versus 700 V), offering additional voltage margin in applications subject to voltage transients or overvoltage conditions. The BTA312-800E,127 is manufactured by WeEn Semiconductors and maintains Active product status. The trade-off is a reduced non-repetitive surge current rating (95A, 105A versus 120A, 126A). Selection depends on whether voltage headroom or surge current capacity is the priority for your application.

Q: Are all substitute parts RoHS compliant?

A: Yes. The ACST12-7ST, BTA12-700SWRG, and ACST1210-7T are ROHS3 Compliant. The BTA312-800E,127 is RoHS Compliant. All parts meet environmental compliance requirements for restricted substance use.

Q: What is the moisture sensitivity level for these TRIACs?

A: All four parts (ACST12-7ST, BTA12-700SWRG, ACST1210-7T, and BTA312-800E,127) carry MSL 1 (Unlimited) moisture sensitivity rating. This indicates no moisture sensitivity restrictions and no special storage or handling requirements.

Q: Can I use the BTA312-800E,127 in a 700 V application?

A: Yes. The BTA312-800E,127 is rated for 800 V off-state voltage, which exceeds the 700 V requirement of the ACST12-7ST. The higher voltage rating provides additional safety margin and is suitable for 700 V applications. The part will function correctly at lower voltage levels within its rated specification.

Q: What is the operating temperature range difference between substitutes?

A: The ACST12-7ST and ACST1210-7T operate from -40°C to 125°C. The BTA12-700SWRG operates from -40°C to 110°C, providing a 15°C reduction in maximum junction temperature. The BTA312-800E,127 operates from -40°C to 125°C. For applications requiring operation above 110°C, the BTA12-700SWRG is not suitable; use ACST1210-7T or BTA312-800E,127 instead.

Q: Are there any differences in gate trigger specifications?

A: Gate trigger current (Igt) is identical across all parts at 10 mA maximum. Gate trigger voltage (Vgt) varies: ACST12-7ST and ACST1210-7T are 1 V maximum, BTA12-700SWRG is 1.3 V maximum, and BTA312-800E,127 is 1.5 V maximum. Higher gate trigger voltage requires slightly more gate drive current to reliably trigger the TRIAC. For sensitive gate applications with limited gate drive capability, the lower Vgt ratings (1 V) are preferred.