STMicroelectronics BTA40-700B

Overview

BTA40-700B from STMicroelectronics is a 40 A, 700 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 AC switching up to 9 kW with proper heatsinking. Used in industrial heating regulation and motor starting circuits requiring high-current phase control.

For engineers reviewing the BTA40-700B datasheet, BTA40-700B pinout, BTA40-700B application, or BTA40-700B equivalent, key selection criteria include its 0.9 °C/W junction-to-case thermal resistance, UL 1557 recognition (file 81734), 500 V/µs dV/dt immunity at 125 °C, and RD91 mechanical torque specification (1.05 N·m recommended).

Technical Context

The BTA40-700B is a four-quadrant, standard-sensitivity TRIAC designed for bidirectional AC conduction without external snubbers in many phase-control applications. Its gate trigger threshold (V_GT ≤ 1.3 V) and latching current (I_L ≤ 70 mA) enable reliable turn-on across all quadrants under varying load conditions.

Thermal performance is defined by R_th(j-c) = 0.9 °C/W and maximum junction temperature of 125 °C, permitting sustained 40 A RMS conduction at T_c = 80 °C. The insulated RD91 package provides reinforced creepage/clearance for mains-connected equipment meeting IEC 60747-6 and UL 1557 requirements.

Key Specifications

Pinout & Package

Package: RD91 - Insulated metal tab power package with M4 mounting screw, UL94 V0 epoxy resin, and recommended torque of 1.05 N·m (max 1.2 N·m). Dimensions: 40.0 × 27.0 × 14.0 mm (L × W × H), weight 20 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTA40-600B, the BTA40-700B adds 100 V blocking headroom for robustness in fluctuating mains environments; versus BTA41-700BRG, it trades higher thermal mass and bolt-down mechanical stability for greater heatsink interface efficiency in panel-mount applications.

Availability

BTA40-700B is available at Aetrix Electronics and suitable for industrial heating regulation, static relay replacement, and motor starting circuits requiring stable component supply, long-term lifecycle support, and certified isolation performance.

Supply support for BTA40-700B 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, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and power applications.

The BTA40 series belongs to ST's high-power discrete TRIAC product line, engineered specifically for robust, isolated AC mains switching in safety-critical industrial controls and energy management systems.

FAQ

What is the maximum continuous case temperature for BTA40-700B at full 40 A RMS current?

The absolute maximum case temperature (T_c) for sustained 40 A RMS conduction is 80 °C, as specified in Table 1 of DS2111 Rev 13. Exceeding this requires derating per Figure 2, where RMS current drops to ~32 A at T_c = 100 °C. Thermal design must maintain T_c ≤ 80 °C using a heatsink sized per R_th(j-c) = 0.9 °C/W and ambient conditions.

Does BTA40-700B require a heatsink in all operating conditions?

Yes - the RD91 package's 0.9 °C/W junction-to-case thermal resistance necessitates an externally mounted heatsink for any continuous load above ~5 A RMS. At 40 A, power dissipation exceeds 60 W (based on V_TM ≈ 1.5 V), making active or substantial passive cooling mandatory to hold T_j ≤ 125 °C and avoid thermal runaway.

Can BTA40-700B be used in three-phase systems?

No - BTA40-700B is a single-pole, two-terminal TRIAC intended for single-phase AC switching only. Three-phase applications require three separate devices (one per phase) with independent gate control and isolation; ST does not specify cross-phase timing or voltage sharing behavior for this part.

Is the 2500 V_rms isolation rating applicable to both A1–tab and A2–tab paths?

Yes - the 2500 V_rms reinforced insulation rating applies between either main terminal (A1 or A2) and the insulated metal tab, as verified under UL 1557 (file 81734). This allows safe mounting to grounded chassis while maintaining functional isolation of both AC line potentials from earth ground.