1500W TransZorb — what the ratings mean for the BOM
The 1.5KE91C-E3/54: The reverse standoff voltage of 73.7 V means the diode draws negligible leakage below that rail level; the breakdown window starts at 81.9 V minimum, and clamping is specified at 131 V maximum at the 11.5 A peak pulse current — so a 72 V bus sees protection before the downstream components exceed their voltage rating. A single bidirectional channel handles both positive and negative transients, saving board space compared to back-to-back unidirectional diodes in the same DO-201AA axial footprint.
Obsolete — sourcing through independent channels
No pin-compatible direct replacement from Vishay is documented — a functional equivalent requires comparing the 73.7 V standoff, 131 V clamp, and 1500 W pulse rating against active TVS diodes in the same DO-201AA package.