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Hello , everyone .
I'm Shailakadesh Pandey , and welcome to my YouTube channel .
Today's topic is Brown node protection circuit in the embedded systems .
Okay .
So let's get started with the topic .
So basically , what is this Brown node protection circuit ?
See , every processor or controller is having a specified operating voltage that it operates at a particular voltage range .
Okay .
And if , the voltage falls below the specified voltage , then there's a possibility that processor may under undergo unexpected program execution or abnormal behavior .
To avoid this unexpected program execution and abnormal behavior , we are having the brownout hornet protection circuit when it is useful only when the , supply voltage of the processor falls below the threshold value that is specified voltage range .
Okay .
So let's get to the next point .
Battery power devices .
See , this brownout protection circuit , this works on the , devices which operate on the battery .
Okay .
Miss , which are battery powered devices because there's a possibility that battery voltage might drop and during such a situation we will require the brownout protection circuit .
Okay .
Fine .
Now , what does this Brown or protection do ?
Okay .
This Brown or protection , how how does it work ?
See whenever the voltage of the controller or processor falls below the specified voltage .
When it falls below the specified voltage to avoid the unexpected program execution , it resets that processor .
Means when the voltage falls below the threshold value value , it resets that processor .
Okay .
And the processor remains in the reset state till the voltage reaches the value which is above the threshold value or threshold value .
Okay .
And , the reset state , after it when the processor reaches the , specified voltage range , the reset is stopped .
Okay .
It gets back to normal working state .
So to avoid this unexpected abnormal behavior of a processor during the , low power , situations or low voltage situations , we have ground mount protection circuit .
Okay .
Now let's see the working of it .
Now , there are some devices .
There are some , controllers or processors which are having built in ground on protection circuit .
And these built in ground out protection circuit monitors the internal supply voltage of the processor or the controller .
Okay .
There is a supply voltage to every processor of controller to monitor that supply voltage we're having the protection circuit .
Okay .
Now , see , you can see the diagram on the right side .
Okay .
This circuit diagram is of the Brownout protection circuit .
Okay .
Where vcc is the supply voltage , Vbe is the voltage across the transistor and vz is the voltage across the Zener diode .
Okay .
So these are the 3 voltages and according to the values of these 3 voltages , the Brownout circuit protection works .
Okay .
Fine .
Now here , Zener diode transistor .
See .
This is the Zener diode and this is the transistor .
These form the heart of your , Brownian protection circuit .
Zener diode transistor are heart of the Brownian protection circuit .
Now working when we get into the working of this Brown Hall protection circuit .
When the value of the VCC , that is the supply voltage , is greater than the sum of vb and vz , that is the sum of voltage across transistor plus this voltage across diode , okay , then the transistor starts conducting .
See , I've written here .
Vcc greater than bb plus vz transistor conducting .
Okay .
So the transistor starts conducting , and when the transistor is conducting , the voltage drop across it is 0 indicating conducting .
What does that mean ?
When the supply voltage VCC is conducting .
What does that mean ?
When the supply voltage VCC is lesser than the voltage across transistor and voltage across the Zener diode .
Okay .
Then it is less than the sum .
It stops conducting .
Okay .
And when it stops conducting , the voltage develops across the transistors .
Low current is flowing through it .
And when the voltage drop develops across the transistor , it indicates the active high .
So what are we getting initially ?
There was active low , then there was active high .
So we will get the reset ones like this .
Okay .
So this is the working of the Brownian protection circuit .
Now , there are , components in this circuit , resistor 1 , 2 , and 3 .
Now what are the values of these resistances ?
Values of the resistance r 1 , r 2 , and r 3 depends on the electrical characteristics of the transistor .
Electrical characteristics of the transistor .
What is the electrical characteristics of the transistor ?
It's , voltage and current ratings .
Okay .
Voltage and current ratings of the transistor .
So , voltage and current ratings , we can get from the datasheet of the transistor .
Okay .
And according to those ratings , we have the value of r 1 , r 2 , and r 3 .
Okay .
We are selecting the values according to the transistor .
Fine .
So , what are the examples of this Brownian protection circuit ?
See , this Brownian protection circuit is also called as a microprocessor supervisor IC .
An example of it is from Maxim Delas , IC DS 123 2 .
IC DS 12 32 from Maxim Delas is example of the Browner protection circuit .
I see .
So it is very important part .
Okay .
I hope you have understood this Browner protection circuit and you have liked this video .
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Thank you for watching .