Obsolete TransZorb — what it means for your BOM
The 1.5KE220C-E3/73: If your BOM line still calls out this exact order code, the sourcing path is a last-time-buy or spot-market procurement. No official Vishay successor is recorded for this part, so a board-level redesign to a current-generation TVS may be the longer-term fix.
1.5 kW bidirectional clamp — the numbers that matter
The reverse standoff voltage is 175 V — the rail it protects should stay below that in normal operation. Breakdown starts at 198 V minimum, and the clamping voltage at peak pulse current (4.4 A) is 344 V maximum. The 344 V clamp figure is the voltage the load sees during a surge event. For a 175 V DC bus or a 120 VAC rectified rail, that clamp gives enough margin to keep downstream semiconductors out of avalanche, provided their V(BR) rating clears 344 V.
DO-201AA axial — board-fit and temperature range
That covers the full industrial temperature range and extends into hot environments like power supplies near transformers or motor drives in enclosures with limited airflow.