Hystereseband

Hystereseband, or hysteresis band, is the input range over which a system that exhibits hysteresis maintains its current state. In devices with two stable states, the output remains unchanged as the input changes within this band until a higher (or lower) threshold is reached to trigger a state transition. The width of the band is the difference between the upper and lower switching points.

In electronic circuits, the band is created by positive feedback, most commonly in Schmitt triggers or relays. A Schmitt trigger defines an upper threshold V_U and a lower threshold V_L; the difference ΔV = V_U − V_L is the hysteresis band. The wider the band, the greater the input noise required to flip the state, improving noise immunity but reducing sensitivity. The band can be adjusted with component values such as feedback resistors, reference voltages, or the characteristics of the switching element.

Hysteresis bands are used in thermostats, position sensors, motor controllers, and power electronics to prevent rapid oscillation or chatter when signals are noisy or slowly varying. They also appear in magnetic materials, where the term is sometimes used to describe the width of the magnetic hysteresis loop, indicating energy losses during magnetization and demagnetization.

Related concepts include hysteresis, Schmitt trigger, switching threshold, and noise immunity.