The reed switch (reed switch) release time is the time required for the switch to turn on after the magnetic field is removed. Taking a relay as an example, when the coil power is turned off, a large back-EMF generation results in rapid opening of the reed. The release time is about 20 μs to 50 μs. If a diode is connected across the coil, this eliminates the back-sensing pulse pressure (which can be from 100V to 200V) and the switch turn-on time is slowed down to about 300μs.
Some designers need a short release time, but they cannot have potential back-sensing pulse-voltage coupling in sensitive digital circuits, so they add a 12 V to 24 V Zener diode in series with a rectifier diode and Coils are connected in parallel. At this time, when the coil power is turned off, the voltage is the reversed Zener voltage value, so that the switch can be turned on within 100 μs.
A graph of the release time increases with the release of the AT value, increasing the release of the AT increases the resilience of the reed, thereby speeding up the release time