AC load-line

youshang

Q:

我們有時會跑buck的AC load-line (ACLL)，

也就是以特定頻率不斷做load transient，

以下圖為例，(V5 current waveform generator)

ILoad在5.2A到17.2A之間以1MHz的頻率切換，

只是我們會掃頻率(ex: 0.1k, 0.3k, 1k, …, 1MHz)，

等於要跑很多次、每次一種頻率。

有聽說新版Simplis有針對ACLL所對應的function，

可能可以一次設定多種頻率。

A:

You can use a File-Defined PWL (FDPWL) source to define your waveform.  The FDPWL source is available starting with SIMetrix/SIMPLIS (SIM/SIM) 8.10.  You can check out the documentation of the File-Defined PWL source here:

https://simplis.com/documentation/simplis/sp_00_master/topics/file_defined_pwl_source.htm

I have attached a ZIP file containing a simple example using the FDPWL source.  Just in case you are not able to run the schematic, I have also outlined a few steps in the PDF file to show you what kind of waveforms a FDPWL source can represent.  If you have a top-level data file that references a few other data files at the correct frequencies, you should be able to accomplish your AC load line simulation with multiple frequencies in one single simulation run.

There is one particular license at Richtek that supports SIM/SIM 8.1 or later.  It is a SIM/SIM Pro license , with a serial number TSS802370/SX802370, and keyed to a license server with a MAC address of 1002b516ec61.

If you are able to use this license to create a FDPWL source, I strongly recommend you to start off with a very simple test circuit so you can familiarize what the waveform of a FDPWL source looks like and make sure the waveform is correct before you copy the source and the data files to a much larger schematic involving the sync. buck converter.

I like to make a comment on your source V5 that you have shown below.  Since it is a voltage source driving the switch S3, the amplitudes of V5 would not be reflected in the load current ILoad.  The action of V5 only switches S3 to open or close.  When S3 is open, it is modeled by its OFF resistance.  When it is closed, it is modeled by its ON resistance.  If the combination of V5 and S3 is replaced by a pulse current source, then it would make sense to define the correct amplitudes for such a current source.  For the same reason, the rise and fall times of V5 are irrelevant.  By the way, you can also use a FDPWL current source.

Regards