The STTH9012TV1 is a fast recovery diode from STMicroelectronics, built with standard silicon technology and housed in the ISOTOP package for chassis-mount, high-power applications.
The 1200 V blocking voltage gives headroom for 400 VAC or 600 VDC bus rails with derating for transients. The 45 A per diode average current, with a forward voltage drop of 2.1 V at 45 A, means each diode dissipates roughly 95 W at full rated current — the ISOTOP package is designed to bolt to a heatsink, so thermal management is mandatory. The 125 ns reverse recovery time keeps switching losses manageable in the 20–100 kHz range, which is where this part earns its keep over a standard recovery diode.
Package and mounting — ISOTOP chassis mount
The ISOTOP package (also called ISOTOP® by ST) is a high-power, electrically isolated baseplate module designed for through-hole bolting to a heatsink. The two independent diodes share the same baseplate but are electrically isolated from it, so you can mount one module per phase without extra isolation hardware. The chassis-mount form factor means the PCB carries only the gate/signal connections — the main current path goes through screw terminals or busbars, not board traces.
The ISOTOP package is a mature, long-running form factor, so supply continuity is good through ST's distribution network.