Purpose of cascaded schmitt trigger in Hall sensor

Thread Starter

sitheesh

Joined Jan 3, 2023
9
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Hi, this is the functional block diagram of a hall sensor IC. Can anyone please explain what is the purpose of these schmitt trigger followed by another trigger? Is single trigger cannot be able perform the function required?
 

ericgibbs

Joined Jan 29, 2010
18,662
Can anyone please explain what is the purpose of these schmitt trigger followed by another trigger? Is single trigger cannot be able perform the function required?
hi sit,
The 1st is a Comparator, with hysteresis, the 2nd is a Schmitt triggered by comparing input voltage against a Vref voltage.

E
 

Ian0

Joined Aug 7, 2020
9,522
I think that the first is a mislabelled differential amplifier. That would make a lot more sense.
What‘s the point of a comparator if its input can only be 5V or 0V?
 

crutschow

Joined Mar 14, 2008
34,060
I agree with Ian0.
It makes little sense to have a comparator with hysteresis (a Schmitt-trigger) in series with another Schmitt-trigger.
I think the amp ahead of the Schmitt-trigger is supposed to be a differential amp (reverse the + and - input polarities) to sense the sensor differential signal, which has a DC offset.
The "Offset Cancel" block refers to the function the differential circuit performs.
 

drjohsmith

Joined Dec 13, 2021
850
View attachment 286631

Hi, this is the functional block diagram of a hall sensor IC. Can anyone please explain what is the purpose of these schmitt trigger followed by another trigger? Is single trigger cannot be able perform the function required?
Also
remember, its a picture done to describe the action of the chip,
drawn by an artist .. not an engineer,
its purpose is to easily convey that the input detects a difference, and the output has been made a good edge,
Id be surprised if you could look at the silicon if there were these actual components.
 
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