TransZorb TVS — 1500 W bidirectional clamp for legacy bus protection
The 1.5KE56C-E3/73: It clamps transients from a 45.4 V reverse standoff voltage to a maximum of 80.5 V at 18.6 A peak pulse current. The bidirectional configuration (single die, symmetrical breakdown) means a single device protects both polarities on a signal or power rail — useful on AC-coupled lines or floating buses where the transient polarity is unknown. Housed in the DO-201AA (DO-27) axial-lead package, it mounts through-hole and is suited for point-of-entry protection on 48 V telecom buses, 36 V nominal industrial supplies, or 28 V aircraft DC rails where the 45.4 V standoff provides margin above the steady-state rail.
Clamping characteristics and temperature envelope
Breakdown voltage is specified at 50.4 V minimum (the avalanche threshold), with the clamping ceiling at 80.5 V. The 18.6 A peak pulse current rating at the 10/1000 µs waveform defines the surge capability — a 1500 W device at this voltage class delivers roughly 18.6 A into the clamp before the junction exceeds its thermal limit. Operating junction temperature range is -55°C to +175°C, which covers military and industrial extremes. The wide Tj envelope means derating for ambient temperature is minimal at typical 85°C board temperatures, but above 125°C the peak pulse power must be linearly derated per the TransZorb application note.
Obsolete — sourcing through independent channels
The 1.5KE56C-/73 is marked Obsolete by Vishay. No official successor order code is recorded in the lifecycle entry. A functionally equivalent replacement would need to match the 45.4 V standoff, bidirectional polarity, 1500 W peak pulse rating, and DO-201AA footprint. Several manufacturers offer pin-compatible 1.5KE56CA-type devices in the same package — confirm the breakdown tolerance and clamping voltage against the original Vishay spec before committing a board spin.