700 V blocking, 12 A RMS — what this triac is built for
The STMicroelectronics BTA12-700BRG is a standard triac rated for 700 V off-state voltage and 12 A RMS on-state current, housed in a TO-220-3 through-hole package. It is designed for AC load switching in applications such as motor speed controls, lighting dimmers, heating controllers, and solid-state relays where the load current and line voltage fall within the 12 A RMS and 700 V peak limits. The gate trigger current is 50 mA maximum and the gate trigger voltage is 1.3 V maximum, which are standard drive levels for a triac of this current class — a simple resistor-limited drive from a microcontroller or logic gate will trigger it reliably. The holding current is also 50 mA maximum, meaning the load must draw at least that much to keep the device latched on after the gate signal is removed.
The BTA12-700BRG is officially marked as obsolete by STMicroelectronics. This means the manufacturer has ceased production and no further last-time-buy windows are open. Any stock available in the independent distribution channel is from existing inventory, not new factory output. If you have this part on a current BOM, you should qualify a replacement or secure a lifetime buy of remaining stock before supply dries up. Because the part is obsolete, pricing and availability are subject to remaining inventory in the channel. No new production is expected, so plan for a replacement design if this part is critical to a long-running product.
Surge current and thermal margin
The non-repetitive surge current rating is 120 A at 50 Hz and 126 A at 60 Hz. This is the peak current the triac can withstand for one half-cycle during a fault event like a shorted load or inrush from a motor start. The 12 A RMS continuous rating gives a 10x margin over the surge rating, which is typical for this class of device — the designer should still ensure the fuse or breaker clears before the junction temperature exceeds the rating.
Package and mounting — TO-220 through-hole
The tab is electrically connected to the MT2 terminal, so an insulating pad and bushing are required if the heatsink is grounded. The through-hole leads are suitable for PCB mounting or point-to-point wiring in chassis-mount applications. The package is supplied in Tube form.