supply current in relation to total current consumed by a circuit

[firstoption]

Good day to all,
Please I need your support and guide on how to get the required current to my circuit.The power supply I intend to use has a switching regulator (RT8289GSP ) with output voltage of 5V/5A(based on the current configuration of the switching regulator-application note from datasheet).However the total current consumed by my circuit is less than 1A(Attiny2313-1pc/tlc5971-4pcs/Max232-1pc/ftdichip2232).According to the datasheet,the switching regulator can output up to 5A which means that the output current can be adjusted just like the output voltage.But after going through the datasheet ,the only formular relating to current is this:Irms=I(out)max Vout/Vin√Vin/Vout-1.The idea of Irms coming into this equation is what actually confused me.i do not know how to figure it out so that I can get the desired output current.My knowledge of electronics is still very limited,i will really appreciate your guide on how I can solve this problem as I can not supply the 5A which the regulator outputs now (based on the current configuration) to the circuit.once again thank you for the support.best regards.

 

[FvM]

You estimate the inut current based on input voltage, output power and converter efficiency.