What this TVS diode does on your board
The SMAJ8.5CAE3/TR13 is a bidirectional Zener TVS diode from Microchip Technology, designed to clamp transients on signal or power rails up to 8.5V reverse standoff. The bidirectional configuration means a single device protects both polarities — useful on AC-coupled lines or where the signal swings through ground. The clamping voltage peaks at 14.4V at the rated 34.7A peak pulse current, so the rail being protected must tolerate that ceiling without damage. The minimum breakdown voltage is 9.44V, giving a guard band below which the diode does not conduct.
Temperature grade and environment fit
The SMA package footprint is well-known — the cathode tab area on the PCB copper plane sets the thermal resistance, so treat the pad geometry as part of the power derating calculation. The part is not rated for power-line protection — it is a signal-line or low-power rail clamp. Keep it on data lines, I/O ports, or auxiliary supply rails where the transient energy stays under 500W.
The part is sourced through our distribution channel and quoted per order.