External sync LT8608 in LTspice?

Question

Hi, 
 I would like simulate a new buck converter design with the LT8608 including the external sync option in the MSOP package. I choose a higher resistor Rt to decrease the switching frequency, but it seems to me that the spice model of the LT8608 ignores the external clock on the sync pin with a higher switching frequency. I also performed a library update in LTSpice (Sync Release). In another test I replaced the LT8608 with the newer IC LT8608 S and now the synchronization works fine. In my opinion the synchronization functionality in the LT8608 is not implemented as mentioned in the answer from "hyao" for the same question from the user "eglid" last year.

John Kevin · Accepted Answer

Hi WeM , Thank you for reporting these findings regarding the LT8608 model. I did test it by setting the device to a lower frequency and applying a 1MHz clock signal in its SYNC pin. It did not synchronize with the external clock. On the other hand, LT8608 S synchronization function is working well. I will reach out to the team who's handling this device so it can be updated soon. We ask for your patience. Thank you.)

John Kevin · Answer

Hi WeM , Our LTspice team have completed the correction for the LT8608 sync function. In the circuit below, I was able to sync the LT8608 to an external clock of 2MHz frequency. 
 Please be advised that we have officially released LTspice 17.1, please download your copy at: 
 https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html Moving forward, all model updates will be reflected on this new LTspice version.

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