Tool/software:
Hi teams,
Mainly, when there is a sudden high current demand, there will be significant spikes in the 12V output ripple test, around 600mV. Some improvement plans have been made, but the results are not particularly good
Could you please provide possible reasons and good suggestions?
1. The schematic diagram of the BUCK section is as follows
2. BUCK Part PCB
3. 12V output ripple waveform
Power the DLP camera with 12V. When the DLP camera is not projecting images, the power consumption is low. After receiving the projection trigger signal, there will be a large current instantly. At this time, the 12V output terminal ripple will have multiple sharp edges corresponding to the number of projected images. as follows
The inductance corresponds to 33uH. When the inductance value is reduced, the ripple increases, while increasing the inductance value does not show significant changes.
Increasing the output capacitor C254 still shows no significant change.
4. The waveform at the SW switch node shows a significant dip and approximately 125MHz ringing
Parallel RC buffer circuit near SW switch node, R=1.8 ohms, C=2.2nF, SW waveform shows no significant change
5. Measure the ripple of the 24V input in the front stage and find that there is a 500Khz oscillation in the input during the projection time (high level), and there is a significant overshoot
