Datasheet

A5972D Closing the loop
Doc ID 13956 Rev 5 17/37
Example:
Considering R
C
= 4.7 kΩ, C
C
= 22 nF and C
P
= 220 pF, the poles and zeroes of A
0
are:
F
P1
= 9 Hz
F
P2
= 150 kHz
F
Z1
= 1.5 kHz
If L = 33 µH, C
OUT
= 100 µF and ESR = 80mΩ, the poles and zeroes of A
LC
become:
F
PLC
= 3.3 kHz
F
ZESR
= 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 9 and Figure 10.
Figure 9. Module plot
Figure 10. Phase plot
The cut-off frequency and the phase margin are:
Equation 16
F
C
33KHz=
Phase margin = 46°