The STMicroelectronics 1.5KE200CARL is a bidirectional Zener TVS diode from the 1.5KE TRANSIL™ series, designed to clamp transients on AC or DC power rails and signal lines rated up to 171 V reverse standoff. The 353 V maximum clamping voltage at 28 A peak pulse current means the protected circuit sees a hard voltage ceiling during a strike. Capacitance of 337.5 pF at 1 MHz is moderate — fine for 50/60 Hz power lines or slow data, but not for high-speed interfaces like Ethernet.
Obsolete — where the part is in the cycle
The 1.5KE200CARL is listed as obsolete. The 1.5KE series is still widely used in legacy industrial and telecom boards, so inventory turns up periodically, but it is not a part you can blanket-order from the factory.
Breakdown and standoff — sizing the protection window
Breakdown occurs at 190 V minimum, so the part triggers cleanly above the normal operating level. Clamping at 353 V is the absolute ceiling the load sees during a pulse. For a 170 V DC bus or a 120 V AC line (rectified to ~170 V), this part sits right at the margin. If your rail is 180 V nominal, you need a higher standoff variant — the 1.5KE series covers 6.8 V through 440 V, so there is a range to pick from.
Package and mounting — DO-201 axial leaded
The DO-201AA (DO-27) axial package is through-hole, designed for wave soldering or hand-soldering into a PCB with 0.8 mm to 1.0 mm diameter holes. The body is hermetic glass-passivated, rated for general-purpose environments. No MSL concern — it is not moisture-sensitive like a plastic SMD part. On a rework bench, the axial leads make it easy to extract and replace with a soldering iron or hot-air station.