0.25W zener — what the rating tells you
The HZ5ALLTD: The 0.25W power dissipation rating sets the upper thermal limit for continuous operation — at 25°C ambient, the diode can dissipate 250 mW before junction temperature exceeds the safe operating area. Derate above 25°C per the standard zener derating curve; in a 70°C ambient environment the usable power drops to roughly 160 mW.
Note the RoHS non-compliant marking — this diode uses lead-bearing termination finish. It cannot be placed in assemblies requiring RoHS exemption-free compliance. For RoHS-mandated BOMs, a lead-free zener in the same power class would be needed.
Bulk package — storage and handling
— loose parts, not on tape-and-reel. This suits low-volume repair, prototyping, or manual-insertion lines where pick-and-place is not used. Store in anti-static tubes or bags; the Bulk format has no moisture-sensitive label, but standard ESD precautions apply.