1. I have to interface a pen-drive with a microcontroller for data logging purpose.
task is to create a FAT based text file in which data will be appended.

2. Is there any usb host like IC available so that it can be interface with any MCU over uart to write data.
Like equivalent of FTDI232 is usb slave which can be interfaced with any MCu to connect it to any computer.

3. i had checked for vnc1l , it has two ports.
Any other IC with single port or cheaper alternative?

 

MAX3421E
https://www.maximintegrated.com/en/products/interface/controllers-expanders/MAX3421E.html
Its spi works good can find arduino code that u can look at and write your own for your uC.

 

VNC2 or MAX3421 looks suitable for application.
http://www.ftdichip.com/Products/ICs/VNC2.htm

 

MAX3421 Has more support because it's used with the ardunio there lot's of premade firmware.
VNC2 would probably be more work.