I want to know how it works What is the output of VCC，I give 5V to inp，but it can't control mos tube
VCC voltage should be around 10V. The controller should be configured close to the diagram shown below in order to work properly. Could you provide me with your schematic? What is the specification of your design? What kind of output load are you trying to drive?
I don't connection load when I control LTC7000,and the VCC voltage is 3.3V
What is the minimum to maximum voltage at VIN? VCC voltage of 3.3V is barely enough to turn on the controller. If possible, use 5V supply at VIN. Make sure VCCUV pin is connected to GND. I would recommend using MOSFET with logic level turn on threshold.