4.5 V rail clamp in a MINI-MELF body
The HZK5ATR-S-E is a 4.5 V zener diode rated for 500 mW maximum power dissipation, housed in a DO-213AC MINI-MELF SOD-80 surface-mount package. It is intended for voltage regulation, clamping, or reference applications on a PCB where a 4.5 V nominal zener voltage is needed and the board is reflow-soldered — no through-hole, no hand-wiring. The ±4.44% tolerance on the zener voltage means the actual Vz sits between roughly 4.3 V and 4.7 V, tight enough for a basic shunt regulator or a low-side clamp but not for a precision reference.
The 500 mW power rating is the total dissipation at the junction; in a MINI-MELF body the thermal path runs through the solder pads to the board copper. For a 4.5 V zener, 500 mW translates to about 111 mA maximum zener current — but only if the board can pull the heat away. The 100 Ohms maximum zener impedance (Zzt) at the test current means the regulation slope is moderate — the output voltage shifts about 100 mV per mA of load change near the knee. That is fine for a clamp or a simple bias rail; for a sharper knee you would look at a lower-impedance zener or a reference IC.
Active production — no LTB worry
No end-of-life notice or last-time-buy date is on file.