Datasheet

A5973D Closing the loop
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Example:
Considering R
C
= 2.7 kΩ, C
C
= 22 nF and C
P
= 220 pF, the poles and zeroes of A
0
are:
F
P1
= 9 Hz
F
P2
= 256 kHz
F
Z1
= 2.68 kHz
If L = 22 µH, C
OUT
= 100 µF and ESR = 80 mΩ, the poles and zeroes of A
LC
become:
F
PLC
= 3.39 kHz
F
0
= 19.89 kHz
Finally R
1
= 5.6 kΩ and R
2
= 3.3 kΩ.
The gain and phase bode diagrams are plotted respectively in Figure 11 and Figure 12.
Figure 11. Module plot
Figure 12. Phase plot
The cut-off frequency and the phase margin are:
Equation 16
F
C
22.8KHz=
Phase margin = 39.8°