STMicroelectronics BTA25-800B

Overview

BTA25-800B from STMicroelectronics is a 25 A RMS, 800 V repetitive peak off-state voltage (VDRM), snubberless triac in TO-220AB insulated package, designed for robust AC phase control and on/off switching in high-noise industrial environments. It delivers 50 mA gate trigger current (IGT), 500 V/µs dV/dt immunity at 125 °C, and 13 A/ms critical rate of rise of on-state current (dI/dt)c without external snubbers - enabling direct drive in motor speed controllers and heating regulators.

For engineers reviewing the BTA25-800B datasheet, BTA25-800B pinout, BTA25-800B application, or BTA25-800B equivalent, this part supports high-reliability AC switching where thermal resistance (Rth(j-c) = 1.7 °C/W), UL1557 recognition, and 2.5 kV insulation withstand are critical selection criteria.

Technical Context

This triac operates in three quadrants (I, II, III) with snubberless capability, eliminating need for RC snubber networks in resistive and inductive loads. Its gate trigger threshold (VGT ≤ 1.3 V) and low holding current (IH ≤ 80 mA) ensure stable turn-on under marginal gate drive conditions.

Thermal design is enabled by validated junction-to-case thermal resistance (1.7 °C/W) and 125 °C maximum operating junction temperature. The insulated TO-220AB package provides 2.5 kV RMS isolation for safety-critical mains-connected equipment.

Key Specifications

Pinout & Package

TO-220AB insulated package with creepage/clearance optimized for 2.5 kV isolation; tab is electrically isolated from A2 terminal.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTB24-800B and T2535-800G, BTA25-800B uniquely combines reinforced insulation, 25 A RMS rating, and snubberless 3-quadrant operation in a through-hole package - making it optimal for safety-certified, serviceable, and thermally conservative AC control designs.

Availability

BTA25-800B is available at Aetrix Electronics and suitable for heating regulation, light dimming, induction motor starting, and static relay applications requiring stable component supply, long-term lifecycle support, and certified isolation.

Supply support for BTA25-800B 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, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

BTA25-800B belongs to ST's high-power triac product line, engineered specifically for robust, snubberless AC switching in safety-critical industrial controls and energy-efficient lighting systems.

FAQ

Is BTA25-800B compatible with zero-crossing trigger circuits?

No - BTA25-800B is a standard 3-quadrant snubberless triac optimized for phase-angle control, not zero-crossing operation. Its gate trigger characteristics (IGT = 50 mA, VGT ≤ 1.3 V) require active timing circuitry to fire at precise points within the AC cycle. Zero-crossing variants (e.g., Z0109MN) use different internal structures and are not interchangeable.

What is the maximum allowable case temperature for continuous 25 A RMS operation?

The datasheet specifies IT(RMS) = 25 A at Tc = 75 °C for the insulated TO-220AB package. Exceeding 75 °C case temperature reduces RMS current derating per Figure 2; at 100 °C case, maximum sustainable RMS current drops to ~15 A. Thermal design must maintain Tc ≤ 75 °C under worst-case ambient and airflow conditions.

Does BTA25-800B require a heat sink in all applications?

Yes - even at 25 A RMS, power dissipation exceeds 2 W (VTM ≈ 1.55 V at 35 A, RD ≈ 16 mΩ). Without a heat sink, junction temperature would exceed 125 °C rapidly. The 1.7 °C/W Rth(j-c) rating assumes a properly mounted, finned aluminum heatsink with thermal interface material; PCB copper alone is insufficient.

Can BTA25-800B replace BTA16-800B in an existing design?

Only with full thermal and surge validation. While both share 800 V VDRM and TO-220AB insulated package, BTA25-800B has higher IT(RMS) (25 A vs. 16 A), higher ITSM (250 A vs. 160 A), and higher IGT (50 mA vs. 35 mA). Gate drive circuitry may need adjustment, and heatsink sizing must be re-evaluated for the increased power dissipation margin.