Define hysteresis in the context of electronics.
1 Answer
In the context of electronics, hysteresis refers to a phenomenon in which the output of a system or component lags behind changes in its input. This delay is due to the system's internal memory or history. Hysteresis is commonly encountered in various electronic devices and systems, and it plays a crucial role in stabilizing circuits and preventing unintended oscillations or switching.
The hysteresis effect is commonly seen in devices like Schmitt triggers and relays. Let's take a closer look at two common examples to understand hysteresis better:
Schmitt Trigger: A Schmitt trigger is a type of comparator circuit with positive feedback that converts an analog input signal into a digital output signal. It has two voltage thresholds: a higher threshold (Vhigh) and a lower threshold (Vlow). When the input voltage crosses the Vhigh threshold, the output switches to a high state. Similarly, when the input voltage crosses the Vlow threshold, the output switches to a low state. However, the key aspect of the Schmitt trigger is the hysteresis between Vhigh and Vlow. This hysteresis ensures that the output remains stable even in the presence of noise or minor fluctuations in the input signal. It prevents rapid toggling of the output when the input voltage is near the threshold values, which would otherwise lead to erratic behavior.
Relay: In the context of electromechanical relays, hysteresis is also known as "differential" or "pick-up" and "drop-out" voltage. When a relay is energized, its contacts close to establish an electrical connection. However, when the input voltage falls slightly below the pick-up voltage, the contacts remain closed due to hysteresis. This prevents the relay from rapidly switching on and off in response to minor fluctuations in the input signal, providing a stable and noise-resistant operation.
Overall, hysteresis is a beneficial characteristic in electronics, ensuring stability and noise immunity in various circuits and devices. It helps prevent unwanted oscillations and erratic behavior, making systems more reliable and less prone to false triggering.
The hysteresis effect is commonly seen in devices like Schmitt triggers and relays. Let's take a closer look at two common examples to understand hysteresis better:
Schmitt Trigger: A Schmitt trigger is a type of comparator circuit with positive feedback that converts an analog input signal into a digital output signal. It has two voltage thresholds: a higher threshold (Vhigh) and a lower threshold (Vlow). When the input voltage crosses the Vhigh threshold, the output switches to a high state. Similarly, when the input voltage crosses the Vlow threshold, the output switches to a low state. However, the key aspect of the Schmitt trigger is the hysteresis between Vhigh and Vlow. This hysteresis ensures that the output remains stable even in the presence of noise or minor fluctuations in the input signal. It prevents rapid toggling of the output when the input voltage is near the threshold values, which would otherwise lead to erratic behavior.
Relay: In the context of electromechanical relays, hysteresis is also known as "differential" or "pick-up" and "drop-out" voltage. When a relay is energized, its contacts close to establish an electrical connection. However, when the input voltage falls slightly below the pick-up voltage, the contacts remain closed due to hysteresis. This prevents the relay from rapidly switching on and off in response to minor fluctuations in the input signal, providing a stable and noise-resistant operation.
Overall, hysteresis is a beneficial characteristic in electronics, ensuring stability and noise immunity in various circuits and devices. It helps prevent unwanted oscillations and erratic behavior, making systems more reliable and less prone to false triggering.