The LM2903 chip is a core hysteresis voltage comparator control module. Based on the original hysteresis module, the power supply filter and one optocoupler isolation output port are added, which is more suitable for industrial control. The hysteresis comparator is mainly used for voltage comparison, especially in the case where the voltage is not stable, it can solve the false trigger and jitter phenomenon of the comparator at the zero boundary. Give a list (if your input signal is 2.45V but there is interference between 2.43-2.47V due to interference or power supply, etc., if the reference voltage is adjusted to 2.45V, then no hysteresis comparison is used. If it is too fast, the comparator will flip very quickly, causing your back acquisition or control to be out of control (especially in the case of relays will be fatal). If hysteresis comparison is added, then the hysteresis range you adjust is 0.03V, then it When it is greater than 2.45V, it will move, but it will be flipped back when it is lower than 2.45-0.03V. For the small jitter in the middle, it will be avoided. This module is widely used in the processing and collection of industrial field signals. After the relay control circuit, it is more suitable for the docking and signal conversion between various modules in industrial control.
1>.the power supply voltage: 5-24V
2>.the output high and low level (output current is about 3-5MA)
3>.The optocoupler isolated output port realizes the independent extraction of the secondary legs of the optocoupler with a 100 ohm current limiting resistor.
Note: Threshold voltage valid range 0 – (supply voltage minus 1V). For example, 5V power supply, the reference threshold voltage effective value is 0-4V, can achieve comparison output. If the threshold voltage is greater than 4V with a 5V supply, then the output will remain low for no output.