1.5 kW TransZorb in a DO-27 barrel
The 1.5KE220A-E3/51: Its 328 V clamping voltage at 4.6 A peak pulse current means a 185 V reverse standoff — the rail it protects should never exceed that in normal operation, or the diode starts conducting. The DO-201AA (DO-27) axial-lead package is a through-hole workhorse — easy to hand-replace on a rework bench if it ever takes a hit that exceeds its single-pulse rating.
Last-buy status and sourcing reality
For a BOM line already qualified to the 1.5KE220A, the last-buy window means procurement should source the balance of the production run now.
Clamping voltage and peak pulse current
The 328 V maximum clamping voltage at 4.6 A (10/1000 µs) sets the survivable transient ceiling — any spike above that level forward-biases the Zener junction and the diode shunts the energy to ground. The 209 V minimum breakdown voltage gives a guard band below the clamp point; the 185 V reverse standoff is the continuous DC rail the part sits across without conducting leakage. At 1500 W peak pulse, this TVS handles the energy of a single lightning-induced surge or inductive load dump on a 185 V DC bus. The 10/1000 µs waveform is the telecom standard — a shorter pulse (8/20 µs) would allow higher peak current before the junction temperature limit is reached.