With the provison to locate the controller as close as possible to the power MOSFETs to minimize gate driver trace runs, the components related to the analog and feedback signals as well as current sensing are considered in the following:
- Separate power and signal traces, and use a ground plane to provide noise shielding.
- Place all sensitive analog traces and components related to COMP1/2, FB1/2, CS1/2, SS1/2, RES and RT away from high-voltage switching nodes such as SW1/2, HO1/2, LO1/2 or HB1/2 to avoid mutual coupling. Use internal layer or layers as ground plane or planes. Pay particular attention to shielding the feedback (FB) trace from power traces and components.
- Locate the upper and lower feedback resistors (if required) close to the respective FB pins, keeping the FB traces as short as possible. Route the trace from the upper feedback resistor or resistors to the required output voltage sense point(s) at the load or loads.
- Route the CS1/2 and VOUT1/2 traces as differential pairs to minimize noise pickup and use Kelvin connections to the applicable shunt resistor (if shunt current sensing is used) or to the sense capacitor (if inductor DCR current sensing is used).
- Minimize the loop area from the VCC1/2 and VIN
pins through their respective decoupling capacitors to the relevant PGND
pins. Locate these capacitors as close as possible to the LM5143-Q1.