91 V zener, 500 mW — the thermal and voltage ceiling
The 1N6023A is a 91 V nominal zener diode from Microchip Technology, rated for 500 mW continuous power dissipation in a DO-35 axial package. The 91 V zener voltage sits in the upper band of standard zener values — useful for clamping, voltage reference, or overvoltage protection in circuits where the rail sits above 60 V. With a ±10% tolerance, the actual zener voltage for any given unit falls between 81.9 V and 100.1 V. For precision reference applications, a tighter-tolerance grade (1N6023B at ±5%) is the usual choice; the A-grade suits general-purpose regulation and transient clamping where the wider window is acceptable.
Reverse leakage and forward drop — the bias and conduction limits
Reverse leakage is specified at 100 nA maximum when biased at 56 V — well below the 91 V zener knee, so this figure represents the leakage in the off-state region. For a high-impedance bias network, 100 nA at 56 V is low enough to avoid loading the source in most signal-conditioning circuits. Forward voltage is 1.1 V maximum at 200 mA forward current — this is the conduction drop when the diode is forward-biased, relevant if the part is used in a bidirectional clamping pair or as a general-purpose rectifier in low-current paths. Maximum impedance (Zzt) is 400 Ohms at the zener test current. This dynamic resistance affects the voltage regulation accuracy under varying current — a 400 Ohm Zzt means a 1 mA change in operating current shifts the zener voltage by up to 400 mV.
-65°C to 175°C — military temperature grade, DO-35 package
This makes the 1N6023A suitable for avionics, downhole instrumentation, and other extreme-environment applications where commercial or industrial temperature grades would exceed their limits. The DO-35 (DO-204AH) axial-lead glass package is the standard through-hole form factor for small-signal zener diodes. It handles the 500 mW dissipation with adequate derating above 25°C — the thermal resistance is low enough that no heatsink is needed in free-air convection at room temperature.
Sourced through authorized distribution channels. The part is supplied in bulk packaging per the standard Microchip packing method for DO-35 axial devices.