The 1.5KE20CAHA0G: For a 12 V rail with a 36 V load-dump transient, the TVS clamps to 27.7 V — well within the 40 V abs-max of most automotive-rated buck converters. The 56 A figure is the peak current the diode can handle for the 10/1000 µs pulse shape; the actual current depends on the source impedance of the transient. The 19 V minimum breakdown voltage is the threshold where the diode starts conducting. Below 19 V the part is essentially open; above it the impedance drops sharply and the clamp engages. This 1.9 V window between standoff (17.1 V) and breakdown (19 V) gives margin for steady-state voltage ripple without the TVS leaking appreciable current.
DO-201 axial package — board-fit and storage
The DO-201AA (DO-27) axial-lead package is a through-hole form factor with a 0.052-inch lead diameter. It requires a 0.040-inch hole in the PCB and typically a 0.100-inch pad diameter for the solder fillet. The body is 9.1 mm long and 5.3 mm diameter — allow 12 mm lead-to-lead clearance for the tape-and-box reel packaging. Tape-and-box (TB) packaging means the parts are on a continuous tape but folded into a box rather than wound on a reel. Store the box in a dry environment below 30 °C and 60 % RH; the DO-201 body is not moisture-sensitive per JEDEC, so no dry-bake is needed before hand-soldering or wave-solder assembly.