AP66200

Document number: DS43720 Rev. 1 - 2

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AP66200

Application Information (continued)

Loop Compensation Design

The regulator uses constant frequency peak current mode control architecture to achieve a fast loop transient response. An accurate current

sensing pilot device in parallel with the upper MOSFET is used for peak current control signal and overcurrent protection. The inductor is not

considered as a state variable since its peak current is constant, and the system becomes a single order system. It is much easier to design a

Type II compensator to stabilize the loop than to implement voltage mode control. Peak current mode control has an inherent input voltage feed-

forward function to achieve good line regulation. Figure 45 shows the small signal model of the synchronous buck regulator and figure 46 is the

compensation network.

Figure 45. Linearized Small Signal Model

Figure 46 is the type 2 compensator.

Figure 46. Type 2 Compensator

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