Hello Hemanth,
Thank you for reaching out. To answer the question "What is the internal equivalent pulldown resistance for I/O pins?" The internal pull-up resistance is 1.5Mohms. Please note that the ISO7762 devices (no F-suffix) have a default high output, and input pins have a pull-up resistance as shown in the I/O diagrams shown below.
As for the title "Leakage current of I/O pins when VCC is not supplied." Also shown in the diagram, are the ESD protection diodes. These diodes are only rated for ESD pulses, and therefore it is not recommended to apply continuous current through the diode. Applying a signal at the input without VCC powered violates the absolute max of the device. For example, if when VCC is 0V, the maximum voltage an input can be is 0.5V.
I hope this helps.
Best,
Andrew
