Other Parts Discussed in Thread: LM5176-Q1, , LM5175, LM5176
Hi,
I am designing a system with input of 8 V to 18 V, output of 17 V at 8.5 A.
I was originally using the LM5176-Q1 for the design, but later switched to the LM5175-Q1 to take advantage of the DCM mode as I worried that reverse current in CCM no load/light load condition will cause a problem. I had a LM74700QDBVRQ1 before the buck-boost stage and I worried that the reverse current will cause the system to shut down.
1.
I am running some PSPICE simulation on the LM5175-Q1 with a load transient of 0 A to 8.5 A at 1 us rise/fall time time at stable output voltage of 17 V. The simulation runs fine at CCM mode but I see that the voltage regulation is not too good at DCM. I see the regulated voltage drops several volts during this transient. Is this limitation real or this is not supposed to happen? Part of my compensation design problem or simulation setup not right?
2.
Is my concern about reverse current in CCM shutting down the LM74700 reasonable? I did some research and simulations and confirmed there is definitely reverse current back to the input source in CCM, but a lot of people have been designing in CCM and didn't have to worry about this problem?
3.
Any recommendations?
Thanks,
Peng