I am using UCD74120 to generate CVDD (1V) voltage for K2K SoC. On checking the voltage across the capacitor of value 220nF (as recommended in the datasheet) connected to BOOT pin of the same IC, it is expected that the output voltage across the same capacitor should be 1V, instead it is producing a voltage of 6V. This BOOT pin is connected to the SW pin of 74120 which is the output pin.
The schematic for the IC is same as that of the reference schematic.
Can you post a picture of the powerstage's switching behavior on an oscilloscope (Voltage between SW and ground)? I want to see if the part is switching normally.
The average voltage* across the inductor will appear to be zero during normal operation, since the inductor is part of a low-pass filter that smooths out the switching seen on the switch node (SW) down to the desired DC voltage (Vout with reference to ground).
*As measured by a multimeter
Just to clarify: Desired output voltage will be seen across the capacitor between "Vout" and Ground. The inductor and the capacitor constitute the low-pass filter that averages out the switching seen on "SW".
