Clamping parameters and surge rating
The P6KE200CA-B is a 600 W bidirectional Zener TVS diode in a through-hole DO-15 axial package. Its 171 V reverse standoff voltage means it stays out of the circuit below that line, then breaks down at a minimum of 190 V and clamps transients to 274 V maximum at the 2.2 A peak pulse current (10/1000 µs waveform). This clamping ceiling is what protects downstream silicon — if the surge pushes the line past 274 V, the TVS shunts the energy to ground.
The wide range also gives margin in designs where the TVS sits near a hot power stage or in a sealed enclosure with limited airflow.
Package and rework note
DO-204AC (DO-15) axial leaded — the leads are thick enough to take a soldering iron or a hot-air preheat without the part body cracking. Polarity is marked by the cathode band; for a bidirectional part like this one, orientation does not matter electrically, but the band still tells you which end is which for visual inspection. The through-hole body sits off the board, so conformal coating flows under it cleanly. If you need to pull it, clip the leads flush and desolder each stub — lifting the pad is unlikely because the through-hole anchor is stronger than the trace.