200 V Zener in a DO-35 can
The 1N6031A is a 200 V Zener diode in a DO-35 axial package, rated for 500 mW continuous dissipation. The 200 V nominal voltage (Vz) places it in the high-voltage end of standard Zener families — useful as a shunt regulator or voltage reference in circuits where the rail sits above 150 V. With ±10% tolerance on the Zener voltage, the actual regulation point for any given unit lands between 180 V and 220 V. That is typical for general-purpose Zener diodes; if your design needs tighter regulation, look at the 5% or 2% suffix variants in the same 1N6031 series.
Leakage and impedance — the real-world limits
Reverse leakage is specified at 100 nA max with 122 V across the junction — that is less than half the rated Vz, so the diode stays quiet in standby. The 2.7 kOhms max Zener impedance (Zzt) means the voltage shifts about 2.7 V per mA of load current change through the knee. For a 500 mW part at 200 V, the maximum continuous current is about 2.5 mA — stay well below that to keep junction temperature under control. The -65°C to 175°C operating range covers military and aerospace temperature profiles, so the leakage and breakdown voltage shift across the band stays within the datasheet limits.