Current Sources and Voltage References

26

Precision resistors, networks, and trimmers

sealed. Because of their very high wattage ratings, they usually have excellent over-

load handling capability, but because of their inherent inductor-like construction, they

also have inductive effects that preclude them from high-frequency applications. Wire-

wounds provide resistance values below 1

Ω

up to approximately 1 M

Ω

, with typical

long-term stability of less than 20 ppm/year.

Compared to the other types, wirewounds are also a natural choice for power cir-

cuits. They often provide a lower cost advantage above 50 K

Ω

. Although wire-

wounds, because of their size and shape, do not naturally ...