24.3V standoff, 27V breakdown — the protection window
The 1.5KE30CH: The 24.3V reverse standoff voltage is the maximum DC or AC peak voltage the TVS blocks without conducting leakage — a 24V rail with 10% tolerance (26.4V max) stays below this threshold, so the TVS remains off during normal operation. Breakdown occurs at 27V minimum (the avalanche threshold), and clamping is specified at 43.5V maximum when conducting 36A — the protected circuit must survive this clamping voltage for the pulse duration. The single bidirectional channel protects against both positive and negative transients in one device — useful for AC-coupled signal lines or power rails that see reverse surges.
The -55°C to 175°C operating junction temperature range covers automotive under-hood ambient (125°C) with margin for self-heating during the surge pulse — the junction temperature rise during a single 10/1000µs pulse is typically under 25°C at rated power. Tape & Reel packaging supports automated insertion for through-hole assembly — the reel quantity is standard for the DO-201 form factor.