In order for the LM27402 to regulate, the feedback loop must be closed and compensated. The LM27402 employs voltage mode control to regulate the output voltage. Voltage mode control requires the LC complex double pole caused by L_out and C_o1 – C_o5 to be compensated to reduce the likelihood of oscillation. The evaluation board incorporates type III compensation which adds three poles and two zeros to the open loop transfer function. The evaluation board is conservatively compensated to grant the user the freedom to make small changes to the powertrain circuitry while maintaining adequate stability. Please refer to the LM27402 High Performance Synchronous Buck Controller with DCR Current Sensing data sheet for the type III compensator design equations. The compensation components include the following:

• R_fb1
• R_fb2
• R_c1
• R_c2
• C_c1
• C_c2
• C_c3