Hello Guys,


Need Help!! I want to sense the current of the load and feed it back to the microcontroller ADC. So basically I want to sense the current driving by the load (flashing lights) and adjust the load current accordingly, like a diagnostic system which sense the load current and adjust it accordingly. In this, I am totaly confused whether to use current sensing switches or current sensing amplifiers. Kindly help me in this regard. The flashing lights drives 1.2A current and supply voltage is 12v.

Thanks in advance

 

Let's see now, what did you find when you dropped the title of this thread, "Current Sensing IC" into Google?

 

I found many from Linear Technology, MAX4080 etc but didnt find the one which may be suitable or my project.

 

No, the MAX4080 is perfect! Buy a thousand of them immediately.

Or perhaps you can explain why it isn't perfect.

 

Try a Google on LTS25-NP. It might work for you.

 

Thank u . Max4080 works fine but, I am getting the output with large variation. Any idea????

 

Your flux capacitor has gone bad.
Seriously though, post the actual circuit and what you´re measuring. No one here is an oracle.

 

I have listen about Ct...

 

For example: The sense resistor used is 0.1 ohm (RSENSE) and voltage accross sense resistor is 0.07v. The gain of the max4080 used is 60. So, Vout should be 0.07 x 60 = 4.20V but infact I am getting Vout = 4.68. More variation. Can any one pls tell me to get less variation. So that I can measure the current more accurately.

 

Except for Rritesh obviously, but no one understands what he means.

 

For example, are you sure the sense resistor is exactly 0.1000ohms and the sensed voltage is exactly 0.070000V? What is the common mode voltage on the sense resistor?
Do you have at least one 100nF ceramic bypass capacitor right next to the chip? Is the measured current truly DC?

 

Here is the circuit attached!

 

@kubeek: pls check the circuit which i have uploaded

 

So, you are measuring some pwm current with an ordinary dc voltmeter, and expect to get accurate and consistent results? Or how fast are the lights flashing?

 

light flashes twice in a second. Similar to ambulance vehicle flashing lights.

 

@kubeek: I checked with the steady lights (drawing constant 0.74A current) not flashing lights.

 

So, are you sure the current you measure is exactly 0.74A, the voltage on the sense resistor is exactly 70mV, etc.? Can you try it with different current, to see if what you get is just offset or the gain is different?

Actually you could use a potentiometer and check what the output does as you vary the voltage on the sense pins.

 

Yes, current drawn by the steady light is 0.74A and the voltage accross 0.1 sense resistor is 70mv. I am using a DC supply not battery of fixed 12v. So i can varry suppy voltage 0v-12v. By varying the supply voltage, the Vout changes. So wot do u think, is the circuit right? or wot else extra i have to add to the circuit, except the 100nf decoupling capacitor near the supply voltage ?.

 

Or do u want me to change the resistor to 0.005 and check the output?. Because it is the lowest sense resistor i have got.

 

Come on guys any one help!!!