13 V regulation with 500 mW dissipation
The 1N6003B/TR: Nominal zener voltage is 13 V with a ±5% tolerance, so the actual breakdown sits between 12.35 V and 13.65 V at the specified test current — tight enough for a 12 V rail clamp or a low-power reference. Rated for 500 mW continuous power dissipation in free air; the DO-35 glass body relies on the lead length and board copper to sink heat, so derate if the ambient exceeds 50°C or if the leads are trimmed short. Maximum zener impedance is 25 Ohms at the test current — this sets the dynamic resistance the load sees, which matters if the diode is used as a shunt regulator rather than just a protection clamp.
Temperature range and leakage
Reverse leakage is specified at 100 nA maximum at 9.9 V reverse voltage, which is 76% of the nominal zener voltage — this gives a clean knee region for low-current biasing.
DO-35 axial package and reel format
Through-hole mounting with 0.020-inch diameter leads; the glass body is hermetically sealed, so it survives humid environments and conformal coating processes without parametric drift.