Help with shunt resistor

[jgauthier]

This is most likely an Ohm's law question, but I feel like I need a little help with it. I have this circuit that I use on a low voltage low current system in order to measure the current.



My device load is 5V around 3A (peak, not sustained).
I'm just looking for some advice on the resistor (1 Ohm pictured). I don't want to use a giant shunt resistor, but I also want to make sure I don't overload the resistor since they are commonly 1/8W rating. It doesn't need to be surface mount, but I really don't want something large either. There may be some consideration I am not taking into this as well. I'm also concerned about voltage drop and need to keep it close 5V.

Thanks!

 

[Bluejets]

Normal approach would be to use 10th of an ohm resistor.
@3A , 1ohm would create too much losses.
A 0.1ohm would do the same job only use a multiplication factor by measuring the voltage drop across it.
What is the load...??
Concerned about change of voltage, put any regulator after the current sense.

 

[Harald Kapp]

The datasheet shows specs for a sense voltage (V_P - V_M of 50 mV (with a max. of 100 mV). Therefore 50 mV is a good operating point for the sense inputs.
With a 3 A load this equates to R_sense = 50 mV / 3 A = 17 mΩ.
SInce 3 A is peak only, you may also chose R_sense = 100 mV / 3 A = 33 mΩ.
The max. voltage drop will then be 50 mV or 100 mV, respectively.