Package and mounting
The HZ30CPTN-E is a 30 V Zener diode from the HZ series, rated for 1 W continuous power dissipation in a DO-35 axial-lead package. It clamps or regulates at 30 V nominal with a ±6.67% tolerance — tight enough for most 24 V rail overvoltage protection or as a shunt reference in low-current bias circuits.
Junction temperature and derating
That extra headroom matters when the diode sits near a hot transformer or in a sealed enclosure — the 1 W power limit applies at 25 °C ambient; at 100 °C you'll need to derate to roughly 0.6 W to stay inside the junction limit.
Reverse leakage and impedance
Reverse leakage is specified at 10 µA maximum with 23 V reverse applied — that's 7 V below the Zener knee, so the diode stays off cleanly on a 24 V rail. The maximum Zener impedance is 18 Ω at the test current; a higher impedance means the regulation slope is softer, so for a precision reference you'd parallel it with a lower-impedance part or buffer it with an op-amp.
Sourcing and lifecycle
The DO-35 axial package is a standard through-hole footprint, so it fits existing PCB layouts without a board spin.