Schmitt Trigger option

[Rosmawati Ismail]

Hi all,

Can anyone tell me which type of schmitt trigger that really suitable for my design.
I want to design a circuit that triggers an interrupt ( rising/falling edge) whenever it detects certain range of input.
For an example, the output will trigger to low when it detects the input is 3.5V and trigger back to high when it detects the input 4V instead of 3.51V. The output will then triggers to LOW once again when it detects 3.5V again instead of 3.99V.

Can anyone help me? Thank you.

 

[KerimF]

Frequency? I mean the maximum possible frequency at the input.
Do you consider using a comparator or opamp?

 

[JoannesPaulus]

Is this schmidt-trigger going to be used in IC design? If so, check figure 1 here.

 

[genius1990]

Hi all,

Can anyone tell me which type of schmitt trigger that really suitable for my design.
I want to design a circuit that triggers an interrupt ( rising/falling edge) whenever it detects certain range of input.
For an example, the output will trigger to low when it detects the input is 3.5V and trigger back to high when it detects the input 4V instead of 3.51V. The output will then triggers to LOW once again when it detects 3.5V again instead of 3.99V.

Can anyone help me? Thank you.

hi i dont thinh u need schmitt trigger for attaining that output..u can use 2 comparators as usend in 555 ic. the upper comparator triggers in 4 volts and lower comparator triggers in 3.5 volt. u can use 2 op-amps as comparators.and resistor network to divide voltage as per ur need.
hope it helps.

 

[Rosmawati Ismail]

genuis,

do you a have schematic for that?
thank you.

joannes,

Is this schmidt-trigger going to be used in IC design?

nope. It is going to be used in electronics circuit where its output acts as an interrupt to microcontroller.

 

[keith1200rs]

Two comparators and a 555 for a Schmitt trigger? You cannot be serious? All you need is a single comparator. **broken link removed**

Keith

 

[genius1990]

What i meant is that
U can use 2comparators as used in a 555ic to attain the required output.
Correct me if i am wrong.
Thanks

 

[keith1200rs]

You could do it that way but then you also need some logic (a flip flop) to combine the two comparator outputs. You only really need one comparator to make a Schmitt trigger with two precisely set thresholds. You simply need to calculate the three resistors based on the conventional comparator based circuit.

Keith.