Tool/software:
Hi sir
Design the lm5576 according to the ti tool, measure the IS PIN signal exceeds 2.1 V, and the output current is >7A. The CURRENT LIMIT CYCLE BY CYCLE phenomenon still does not occur. Only the voltage drops from 12v to 10v ，What is the possible reason?
output current 1A up to 7A，Vout 13V down 11V，Vout no auto restart
CH1:Vsw，CH2 : Vis，CH3:Vout，CH4:IL
2.IL current
3.IS pin voltage
4. Vout
Hello Hsieh
LM5576 have cycle by cycle current limit. Operation of current limit is explained in section 7.4.7 as follows.
If the DC level of sample and hold circuit is higher than 2.1V. Regulator skips the pulse. This allows inductor current to fall for more time than normal cycle. This operation is bit different than hiccup mode, where device shuts off for certain duration. That's the reason you are not seeing any Vout auto start. However, Vout will fall as average current supplied by the regulator has reduced. You can also notice reduced frequency before and after applying the current step.
I hope this answers your question. Let me know if you any further doubts or need any clarification.
Thank you
Regards
Onkar
