We are trying to use LTC7851 as the controller of a 4-phase buck converter. However the input voltage rating and the output voltage rating exceed the sense voltage range of both the feed-forward control and current sharing control pins. Before we try to put voltage dividers to scale down the pin voltage, we need to figure out the internal structure, or at least the input impedance of these control blocks. However, they are unclear in the datasheet.
1. About the current sharing. On page 27, it says that the current sharing loop is internally compensated but it isn't indicated on the block diagram on page 11 that how the internal compensation network is connected to the current sense amplifier. I need to know what type of the compensation it is and how it is connected because I need to connect some resistor voltage divider to the current sensing pin and do not want to interrupt the stability of the current sharing loop.
2. About the line voltage feed forward. Similar as the first question, may I know the feedforward circuit which is not indicated in the block diagram on page 11? I also need to connect some resistor voltage divider to this pin and do not want to interrupt the stability of the feedforward loop.
Thanks a lot for your help!