Hi,

Can you help me how to design a circuit to monitor the voltage at the MOSFET source terminal?.

 

hi pp,
What sort of question is that.??
A lot more information is required in the question, if we are not to waste more of our time guessing.

If you have a draft circuit, post it.
E

 

The voltage across the drain of MOSFET is 24V and current is passing through is 1A.

 

hi,
Post your full circuit, the questions are too vague for us to give meaningful replies.
E

 

I want to monitor the voltage at the source terminal of the MOSFET.

 

I want to monitor the voltage at the source terminal of the MOSFET.

It is always 0v Gnd

Update:
You originally posted the drain of MOSFET is 24V and current is passing through is 1A.

This is what your LTS sim shows.

 

It is always 0v Gnd

Update:
You originally posted the drain of MOSFET is 24V and current is passing through is 1A.

This is what your LTS sim shows.

Yes, I know that, but, I want to implement some circuit between the drain source and ground, to monitor the voltage. As I know, shall I put the shut resistor between the MOSFET and GND, so that we will measure the voltage, Right?. See below circuit. Please let me know is it correct or wrong and give me some suggestions if I'm wrong.

 

hi,
Using a 1R Shunt will give a Vout of around of only 120uV.

After a 2:1 divider half that.
Why do you need to know the Source current and how are you going to use the 120uV signal.??

 

hi,
Using a 1R Shunt will give a Vout of around of only 120uV.

After a 2:1 divider half that.
Why do you need to know the Source current and how are you going to use the 120uV signal.??

That is example circuit which I have attached above. I want to design a circuit which will read the voltage 24V.

 

That is example circuit which I have attached above. I want to design a circuit which will read the voltage 24V.

So, design and post a draft circuit that you consider that would be a good starting point for us to discuss.

 

I planning like this, but, the problem here is that the voltage at the divider is 3.3V all the time, it should not be like that. I want like when the MOSFET is switch on the divider output should be 0V and when the MOSFET is switch off then the divider output should be 3.3V.

 

hi pp,
If you do not already know why that circuit you posted, is giving a fixed 3.3v, then IMHO you are studying for the wrong profession .

I am beginning to suspect that you are playing games with us.

E

 

No, why should I play the games, I never ever do that. I'm asking the question. Please don't get angry. If I ask you wrong question, please correct me. I don't know how to implement the circuit. I'm learning please support me.

 

Look at what your divider is connected to. How can that be anything other then 3.3V?

Edit: Hint, unless there is a series resistance on the 24V source, its terminal is always at 24V.

Bob

 

Look at what your divider is connected to. How can that be anything other then 3.3V?

Edit: Hint, unless there is a series resistance on the 24V source, it's terminal is always at 24V.

Bob

Yes, yes.. I got it why he get angry. Sorry for that mistake.

 

Then, anyone can you tell how to design a circuit to monitor the voltage at low side and high side.

 

First, you need a circuit that does something.

Edit: start by putting the inductor back in.

Bb

 

hi,
To be clear, I am not angry.
I am becoming frustrated in having to keep guessing in order to discover what you are actually trying to do and more importantly WHY.

Why do you need to measure those two values.????

 

What exactly are you trying to do?
Measuring the voltage across a resistor from the source to ground allows you to calculate the current.
Is that what you want?

 

I think he is trying to build a boost circuit, but decided a couple of components weren't needed.

Edit: I have built simulated his circuit both with and without the inductor. Even with the inductor, the voltage at the drain (not source) stays very close to 24V. This is because of the two missing components plus the inductor being way to small. Adding two components and changing the inductor and the timing produces a working boost converter, and the drain voltage does go to near zero as he thinks it should.

Bob