A solution to acheive stablity while maintaining minimum Cout capacitance on MAX20743
Maxim usually recommends to use more than 900uF as Cout for MAX20743 application. However, in most cases, customers want to reduce the capacitance due to cost issue. For example, 330uF x 2 or 470uF x 1 is used according to a load transient condition. In order to meet the customers' need, Maxim suggest applying external RC lag compensation circuit. RC lag compensation consists of 1k Ohm + 10nF in series between the VSENSE+ and VSENSE-
With Cout 1x470uF + 3x47uF + 2x22uF, Rgain 0.9mohm, and 470nH inductor, simulation result shows the result below.
Without the RC lag compensation, the PM=31 degree and BW=168kHz. After adding the 1k Ohm + 10nF network between Vsense+ and Vsense-, the PM=76 degree and BW=72kHz