If the maximum full-scale output of a current-sense amplifier I use is 4.9V (it will be given in the manual), its gain is 20, and the maximum current signal I want to measure is 0.2A, then the maximum Rshunt value should be:
(4.9V/20)/0.2A=1.225Ω;
In other words, the Rshunt value I chose...