hi, i am looking for a linear current sensor.
i need a the supply to be 5V
the current will be to 0-4A
You are not giving enough information to get a more specific answer. Is there a specific problem with the AD8218 ?Are you able to use the selection table ? With regard to "changes up to 5V, the AD8218 output can swing up to 4.9V with a 5V supply. You will not find any other part that can do better than that.
If the change that you are talking about is on the input, then that would be unusual and also not easily done with a current sense IC. They are designed for lower voltage across a sense resistor, so there is not too much power dissipation in the resistor. For your example of 0-4A, a candidate sense resistor would be .062 ohms with a power rating of at least 1 watt. That would develop .248V at 4A. With a gain of 20 in the current sense amplifier, the output would ideally go to 4.96 volts. But probably not in practice, since the 5V supply is not quite high enough to get 4.96V output. Considering tolerances on supply voltages, sense resistor, and amplifier gain, it would be better to use a lower value of sense resistor such as 0.05 ohm. Then you would have a nominal 4V output at 4A. That would be practical with a 5V power supply.
There are many many choices, depending on your requirements. For example, does it need to measure current flowing in both directions ? Only a few current sense ICs have bidirectional capability. The most common and inexpensive parts use a low value sense resistor, and they have only modest accuracy and significant offset errors. Offset errors lead to significant measurement error near 0. Still, they are good enough for many applications. The ZXCT1009 is an example of these basic parts. Other parameters that relate to these parts is the voltage range of the line in which you are measuring the current, bandwidth of the measurement, gain, etc. In many applications engineers will make their own current sense amplifier from a few discrete parts. It all depends on the specific requirements.
one direction, high side, i need the output to be voltage (up to 5V)
AD8218 is a nice part. Otherwise see the table of current sense amplifiers here;
i need to measure changes up to 5 volts. what do you suggest?
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