A window detector circuit, also called window comparator circuit or dual edge limit detector circuits is used to determine whether an unknown input is between two precise reference threshold voltages.[1] It employs two comparators to detect over-voltage or under-voltage.[2]
Each single comparator detects the common input voltage against one of two reference voltages, normally upper and lower limits.[3] Outputs behind a logic gate like AND detect the input as in range of the so-called "window" between upper and lower reference.
Window detectors are used in industrial alarms, level sensor and controls, digital computers and production-line testing.
| > Urefbot | 0 | 1 | 0 |
| < Ureftop | 1 | 0 | 0 |
| < Ureftop > Urefbot | 1 | 1 | 1 |
If Uin is greater than Urefbot and Uin is lower than Ureftop then both comparators' outputs will swing to the logical high and turn on the AND gate output.