LTC4120 block diagram


   I'm student of a Masters Degree in Electrical Engineering at University of Coimbra. Because of COVID-19 we are not having classes and we have to simulate a circuit from a project. In that project it was intended to be used an LTC4120 and an LTC4125 to make an wireless power transmission system. As we can not be at the university we have to simulate this IC and we are having some trouble with, and your help would be appreciated. In the page 10 of the LTC4120 datasheet there are some blocks named LDO, PWM, CNTRL and DHC wich do not have a block diagram for each one. So we would like to know if there is a way to help us with this matter.

Best regards,

Gonçalo Santos 

  • +1
    •  Analog Employees 
    on Apr 29, 2020 10:22 PM 8 months ago

    Hi Gonçalo ,

    It depends on how complicated you want your model to be. Do you want a behavioral model of the block that can provide good input and output with some software commands or you want a complicated circuit model with transistors. I suggest that you should probably start with the behavioral model of these blocks and start from the basic model first, for example a model without closed loop control. 

    Assuming you are using LTspice for simulation. For LDO, you can simply use a voltage source with enable (or a voltage source with ideal switch that controlled by a voltage signal). For PWM block, you can probably just use a square-wave source as clock as a starting point to drive a half bridge formed by ideal switched. For CNTRL block, you can build it with some ideal comparators that trigger the fault pin when NTC pin is within a certain window. The CHRG output is a bit more complicated, and you might need another squarewave generator with frequency controlled by a voltage signal or something similar. For DHC block, it is just a comparator that looks at input voltage and a output drain pull-down as output. 

    The easiest way to run a simulation of a wireless charging system is to use the existing LTC4120 spice model: