1500W bidirectional TransZorb — obsolete but spec'd for replacement
The 1.5KE7.5CA/54: Its 6.4V reverse standoff voltage protects 5V or 6V rails, clamping transients at 11.3V maximum before the downstream IC sees overvoltage. This part is listed as obsolete by Vishay. For existing BOM lines that require this exact order code, sourcing runs through independent distribution channels — availability is confirmed per RFQ, not from factory stock.
Clamping voltage and pulse current — the fit check
The 11.3V maximum clamping voltage at 133A peak pulse current (10/1000 µs) sets the upper limit the protected circuit sees. A 5V rail with a 12V abs-max input rating has margin here, but a 3.3V rail does not — the clamp voltage exceeds the typical abs-max of 3.6V for 3.3V logic, so a lower-voltage TVS or a series resistor is needed ahead of the diode. Minimum breakdown voltage is 7.13V, with the reverse standoff at 6.4V. The standoff is the DC bias the diode leaks under — at 6.4V the leakage is negligible for most circuits, but the diode starts conducting above that threshold, so the rail must stay below 6.4V in normal operation. The 1500W rating derates above 25°C — at 175°C the peak pulse power drops to roughly 25% of the 25°C value, per the standard derating curve for axial-lead TVS diodes.
Sourcing the obsolete 1.5KE7.5CA/54
Vishay's official status is obsolete — no last-time-buy window or successor order code is recorded in the lifecycle entry. The part is a bidirectional single-channel device in a DO-201AA (DO-27) axial-lead package, supplied on tape and reel. For a BOM line that calls out this exact Vishay order code, the sourcing path is through surplus and broker inventory. No pin-compatible direct replacement from Vishay is documented; a functional equivalent would need the same 6.4V standoff, 1500W rating, and bidirectional configuration in the same DO-201AA footprint. That cross-reference is confirmed at RFQ time, not assumed.