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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics BTA40-800B

Name: BTA40-800B
Brand: STMicroelectronics
SKU: BTA40-800B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BTA40-800B

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: RD91-3 (Insulated)

Datasheet:: BTA40-800B.pdf

Description:: TRIAC 800V 40A RD91

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BTA40-800B from STMicroelectronics is a 40 A, 800 V RMS insulated triac in RD91 package, rated for 2500 V_rms isolation between main terminals and heatsink. It delivers 50 mA gate trigger current (I_GT), 1.55 V on-state voltage (V_TM) at 25 °C, and supports phase-control AC switching up to 9 kW with proper heatsinking in motor speed controllers and light dimmers.

For engineers reviewing the BTA40-800B datasheet, BTA40-800B pinout, BTA40-800B application, or BTA40-800B equivalent, key selection criteria include its 0.9 °C/W junction-to-case thermal resistance, 50 A/µs critical dI/dt rating, UL1557 recognition (file 81734), and non-insulated RD91 mechanical interface optimized for high-power conduction cooling.

Technical Context

The BTA40-800B operates as a bidirectional AC switch with four-quadrant triggering capability, enabling reliable turn-on under both polarities of A2 relative to A1. Its gate threshold voltage (V_GT) is ≤1.3 V, and it maintains ≥500 V/µs off-state dV/dt immunity at 125 °C with open gate.

Thermal design relies on direct case-to-heatsink conduction via the RD91 package's isolated tab, supporting continuous 40 A RMS conduction at T_c = 80 °C. The device sustains 420 A non-repetitive surge current (16.7 ms) and exhibits 1000 A²s I²t fusing capability, making it suitable for inductive load switching with controlled commutation.

Key Specifications

Parameter	Value and Actual Design Meaning
I_T(RMS)	40 A - Continuous AC load current handling at 80 °C case temperature
V_DRM/V_RRM	800 V - Peak repetitive off-state blocking voltage per quadrant
I_GT	50 mA - Maximum gate trigger current required for reliable turn-on
R_th(j-c)	0.9 °C/W - Junction-to-case thermal resistance enabling efficient heatsink coupling
dI/dt (critical)	50 A/µs - Minimum rate of rise of on-state current before false triggering
V_TM	1.55 V - Maximum on-state voltage drop at 60 A pulse, defining conduction loss
I²t	1000 A²s - Fusing energy limit for short-circuit withstand without destruction

Pinout & Package

The BTA40-800B uses the RD91 package: a bolt-down, non-insulated power triac housing with isolated tab rated at 2500 V_rms, UL94 V0 epoxy resin, and recommended mounting torque of 0.9–1.2 N·m.

Pin/Terminal	Circuit Role	Design Meaning
A1 (MT1)	Main Terminal 1	AC line or load return path; referenced to gate for triggering polarity
A2 (MT2)	Main Terminal 2	AC line or load hot side; voltage polarity relative to A1 defines quadrant operation
G	Gate	Control input for bidirectional turn-on; triggers conduction when \|I_G\| ≥ I_GT and \|V_A2-A1\| ≥ 12 V

Key Features

Feature	Design Value
UL1557 Recognition	Validated isolation safety per file 81734 - enables use in certified industrial control systems without additional creepage/clearance validation
High Surge Withstand	420 A non-repetitive peak current (16.7 ms) - supports motor startup surges and transformer inrush without failure
Low Thermal Resistance	0.9 °C/W junction-to-case - reduces thermal derating and allows compact heatsink sizing for 9 kW AC systems
Four-Quadrant Triggering	Guaranteed turn-on in all quadrants with I_GT ≤ 50 mA - eliminates need for external snubbers or gate polarity conditioning circuits

Applications

Heating Regulation Systems

Light Dimming Circuits

Use Scenario: Precise temperature control in industrial ovens using zero-crossing or phase-angle firing.

IC Role / Device Role / Timing Role: Main AC power switch modulating RMS voltage delivered to resistive heating elements.

Use Value: 800 V blocking rating accommodates 400 VAC line transients; 40 A rating supports >9 kW heater banks with single-device implementation.

Use Scenario: Mains-powered residential/commercial LED and incandescent lamp dimming.

IC Role / Device Role / Timing Role: Bidirectional phase-control switch synchronized to AC zero-crossing for smooth brightness adjustment.

Use Value: 50 mA I_GT ensures compatibility with low-power microcontroller GPIOs; 1.55 V V_TM minimizes conduction loss and self-heating at partial conduction angles.

Induction Motor Starting

Static Relay Modules

Use Scenario: Soft-start and run-capacitor switching in single-phase induction motors (e.g., HVAC compressors).

IC Role / Device Role / Timing Role: High-current AC switch replacing electromechanical contactors to eliminate arcing and wear.

Use Value: 420 A surge rating handles locked-rotor currents; 50 A/µs dI/dt immunity prevents false turn-on during rapid current rise at motor energization.

Use Scenario: Solid-state replacement for mechanical relays in PLC output modules and building automation panels.

IC Role / Device Role / Timing Role: Isolated AC output stage providing galvanically separated load switching with no moving parts.

Use Value: 2500 V_rms insulated tab meets reinforced insulation requirements for SELV/PELV interfaces; UL1557 certification simplifies system-level safety approvals.

Equivalent & Alternatives

The following parts are listed as comparable options for similar triac-based AC switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BTA41-800BRG	TOP3 insulated package (4.5 g), lower thermal resistance (0.9 °C/W same), identical electrical specs	Requires PCB-mounting and smaller heatsink; better suited for space-constrained board-level designs	Select when isolation must be integrated into package footprint rather than achieved via heatsink mounting hardware
BTB41-800BRG	TOP3 non-insulated package, same 40 A/800 V rating but no 2500 V_rms tab isolation	Lower cost and weight; requires external isolation barriers for safety-critical installations	Select when system-level isolation is implemented elsewhere (e.g., transformer, optocoupler) and board density is prioritized

Compared with BTA41-800BRG and BTB41-800BRG, the BTA40-800B offers superior mechanical robustness for bolted heatsink mounting, higher thermal mass for transient surge absorption, and field-proven reliability in high-vibration industrial enclosures - making it optimal for panel-mounted static relay and motor controller assemblies.

Availability

BTA40-800B is available at Aetrix Electronics and suitable for heating regulation systems, light dimming circuits, induction motor starting, and static relay modules requiring stable component supply across extended production lifecycles.

Supply support for BTA40-800B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The BTA40-800B belongs to ST's high-power triac product line, engineered specifically for robust, maintenance-free AC power control in harsh environments - emphasizing thermal resilience, surge immunity, and safety-certified isolation.

FAQ

What is the maximum allowable case temperature for continuous 40 A operation?

The BTA40-800B is rated for 40 A RMS conduction at T_c = 80 °C, as specified in Table 1 of DS2111 Rev 13. Exceeding this temperature requires derating per Figure 2; at 100 °C case, maximum RMS current drops to approximately 28 A. Thermal design must ensure heatsink interface resistance and ambient conditions maintain T_c ≤ 80 °C under full load.

Does the BTA40-800B require a heat sink for 40 A operation?

Yes - the RD91 package relies entirely on conduction cooling through the isolated tab. Without a properly sized and mounted heatsink, junction temperature will exceed 125 °C even at modest currents. ST recommends using thermal interface material and applying 0.9–1.2 N·m torque to the mounting screw to achieve the specified 0.9 °C/W R_th(j-c).

Can the BTA40-800B be triggered directly by a 3.3 V microcontroller GPIO?

No - its maximum gate trigger current is 50 mA, and V_GT is up to 1.3 V, but the gate requires sufficient energy (I_G × t) to overcome internal capacitance. A 3.3 V GPIO cannot source 50 mA continuously; a dedicated gate driver (e.g., MOC302x optocoupler with series resistor) is required to ensure reliable, noise-immune triggering across all quadrants.

Is the BTA40-800B compliant with RoHS and REACH regulations?

Yes - the BTA40-800B uses RoHS-compliant (2002/95/EC) lead-free packaging and UL94 V0 flammability-rated epoxy. ST confirms full compliance with EU RoHS Directive 2011/65/EU and REACH SVHC thresholds as documented in their ECOPACK environmental reports, accessible via www.st.com/ecopack.

BTA40-800B Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: RD91-3 (Insulated)

Packaging:: Tube

Product Status:: Active

Triac Type:: Standard

Voltage - Off State:: 800 V

Current - On State (It (RMS)) (Max):: 40 A

Voltage - Gate Trigger (Vgt) (Max):: 1.3 V

Current - Non Rep. Surge 50, 60Hz (Itsm):: 400A, 420A

Current - Gate Trigger (Igt) (Max):: 50 mA

Current - Hold (Ih) (Max):: 80 mA

Configuration:: Single

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Chassis Mount

Supplier Device Package:: RD91

BTA40-800B FAQ

1.How can I place an order for BTA40-800B through Aetrix?

Please submit a Request for Quotation (RFQ) for BTA40-800B on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BTA40-800B reliable?

The price and inventory of BTA40-800B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BTA40-800B is usually 5 days.

3.What payment methods are accepted for BTA40-800B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BTA40-800B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BTA40-800B?

BTA40-800B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BTA40-800B order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BTA40-800B?

For technical support, including BTA40-800B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BTA40-800B requirements.

6.How does Aetrix verify that BTA40-800B is sourced from the original manufacturer or authorized distributors?

All BTA40-800B products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BTA40-800B meets industry standards.

7.What is the process for return or replacement of BTA40-800B?

All BTA40-800B units undergo pre-shipment inspection (PSI). If there is an issue with BTA40-800B, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BTA40-800B part is unused and in its original packaging.

Return procedure for BTA40-800B:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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