Application Example: Post Regulator for a Switching Converter
The FAN2560 is an ideal choice for battery-powered
equipment. The low quiescent bias current can be
supplied directly from the battery, while the input
voltage can come from a high-efficiency buck regulator,
like FAN5350. This combination provides both best
efficiency and low noise output. As can be seen in the
scope pictures below the schematic, the already-low
output voltage ripple, inherent to a switching regulator,
is significantly attenuated by the FAN2560 at any
frequency within the switching operating range.
Figure 23. Post Regulator for a Switching Converter
Figure 24. PFM Mode (100mA Load) Buck Ripple
Rejection, Horizontal Scale: 500ns/div.
Figure 25. PWM, 3MHz (300mA Load) Buck Ripple
Rejection, Horizontal Scale: 200ns/div.
© 2006 Fairchild Semiconductor Corporation
FAN2560 • Rev. 1.0.0
9
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