AST1S31HF Datasheet, PDF (15/33 Pages) STMicroelectronics – Internal soft-start and enable

AST1S31HF
Functional description
So closing the loop the loop gain G_LOOP(s) is:
Equation 15
G_LOOPs = G_COs  G_DIVs  G_EAs
Example:
VIN = 3.3 V, VOUT = 1.2 V, Iomax = 3 A, L = 0.91 H, Cout = 22 F (MLCC),
R1 = 100 k, R2 = 200 k(see Section 7.2 on page 20 and Section 7.3 on page 21 for
inductor and output capacitor selection guidelines).
The module and phase Bode plot are reported in Figure 7.
The bandwidth is 230 kHz and the phase margin is 70 degrees.
Figure 7. Module and phase Bode plot
120
102
84
66
48
30
12
6
 24
 42
 60
0.1
1
10
 17.5
 45
 72.5
 100
 127.5
 155
 182.5
 210
0.1
1
10
100
110³ 110⁴ 110⁵ 110⁶ 110⁷
Frequency [Hz]
10
100
110³ 110⁴ 110⁵ 110⁶ 110⁷
Frequency [Hz]
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