/diy/ - Do It Yourself

>>1436496
The initial tolerance is usually 5%, albeit better diodes exist. The breakdown is rather gradual with 5V and lower voltage zeners, while higher voltage zeners are better. And like everything, zeners have (quite significant) temperature coefficient. 5V zeners are somewhat better than the rest in this respect.

The closest thing to an accurate zener is the so called reference diode, which has a zener and a temperature compensation diode in series. This improves particularly the tempco, but reference diodes are available with quite tight initial tolerances, too.

Reference diodes are rarely used, though. Usually people use IC references, which are available as "zener-like" shunt references, too. They're generally much closer to the ideal zener than zener diodes are. However, if the off-state leakage is the most important parameter to you, you might need to build something more complex using an opamp or whatever.