12 V clamp for automotive rails
It delivers a nominal zener voltage of 12 V with ±3% tolerance, rated for 500 mW continuous power dissipation in the DO-219AC (microSMF) surface-mount package.
What the 500 mW rating means for your board
At 12 V nominal, 500 mW translates to roughly 42 mA continuous zener current before hitting the thermal ceiling at 25°C ambient. In a 105°C under-hood environment, the allowable dissipation drops to about 60% of the 500 mW rating, so budget the clamp current accordingly.