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10 ECEN5807 CPM

11 ECEN5807 CPM High-frequency pole (from the accurate averaged model (4))

12 ECEN5807 CPM Compare to first-order approximation of the sampled-data control-to-current model Control-to-inductor current response behaves approximately as a single-pole transfer function with a high-frequency pole at Model (4) is consistent with the sampled-data small-signal model

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15 ECEN5807 CPM DC gain of line-to-output G vg-cpm (based on model (4))

16 ECEN5807 CPM Example CPM buck converter: V g = 10V, L = 5  H, C = 75  F, D = 0.5, V = 5 V, I = 20 A, R = V/I = 0.25 , f s = 100 kHz Inductor current slopes: m 1 = (V g – V)/L = 1 A/  s m 2 = V/L = 1 A/  s D = 0.5: CPM controller is stable for any compensation ramp, m a /m 2 > 0 Select: m a /m 2 = M a /M 2 = 1, M a = 1 A/  s

17 ECEN5807 CPM Example (cont.) Duty-cycle control Peak current-mode control (CPM)

18 ECEN5807 CPM Compare to first-order approximation of the high- frequency sampled-data control-to-current model Control-to-inductor current response behaves approximately as a single-pole transfer function with a high-frequency pole at

19 ECEN5807 CPM 2 nd -order approximation in the small-signal averaged model

20 ECEN5807 CPM 2 nd -order approximation in the small-signal averaged model