5. Feedback Loop Phase and Gain Measurement Results (Bode Plots)
The Si3406 device integrates a current mode controlled switching mode power supply controller circuit. Therefore, the application is a
closed-loop system. To guarantee a stable output voltage of a power supply and to reduce the influence of input supply voltage varia-
tions and load changes on the output voltage, the feedback loop should be stable.
To verify the stability of the loop, the loop gain and loop phase shift has been measured.
-180
-90
0
90
180
-80
-60
-40
-20
0
20
40
60
80
100
1 000
10 000
100 000
Figure 5.1. Si3406-Non-ISOFB-EVB-C3 Measured Loop-Gain and Phase Shift
Table 5.1. Measured Loop Gain and Phase Shift
Frequency
Gain
Phase
Cursor 1 (Phase Margin)
19.1 kHz
0 dB
78°
Cursor 2 (Gain Margin)
47.1 kHz
–7 dB
0 °
UG332: Class 3 Non-Isolated Evaluation Board for the Si3406
Feedback Loop Phase and Gain Measurement Results (Bode Plots)
silabs.com
| Building a more connected world.
Rev. 0.1 | 7
