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续流用的，开关和电感同时作用，
6 w. I9 s, ^1 A' K! hWith the PFET on, the input supply charges COUT and6 R6 x; ~0 v' T, b
supplies current to the load via the series path through the) c, q& F/ Z' `" ?; S" c
PFET and the inductor. Current through the Inductor ramps1 j: F3 }' V9 }& U" z3 ]! @2 B
up linearly and the output voltage increases. As the FB voltage# R+ ~& l( O4 [- D
reaches the upper threshold, which is the internal reference
; w C8 k. \9 p5 J: P W. U' ?4 Uvoltage plus 10mV, the output of the comparator
( b7 z% {/ M1 X6 N+ j% s' R, Ochanges from low to high, and the PGATE responds by turning
7 Y# ~, R2 e# ithe PFET off. As the PFET turns off, the inductor voltage
9 {, i* [) P {' \reverses, the catch diode turns on, and the current through& q: r5 U1 F9 G. I( H4 Q
the inductor ramps down. Then, as the output voltage reaches
8 U" |4 m1 \: f' R6 g4 fthe internal reference voltage again, the next cycle starts |
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发表于 2011-6-10 10:08
