Can Any one suggest me a good interface IC for the purpose USB communication
Cost effective IC which will give a parallel or serial output from the USB port... SO that i can interface with this by an external micro-controller......
Is there something I'm missing? I didn't see anything about a programmer. I'm thinking there are other posts here that explain more about what he wants which is not a simple USB to serial interface.
Otherwise FTDI is pretty much the standard in USB->serial interfaces. FT232R is a simple USB to serial interface. It's SMD, so if you have trouble working with it, there are breakout boards available everywhere.
There's also the CP2102 that is popular and I just saw this on Sparkfun a little while ago. No serial output, but it does do parallel like the OP is looking for and it looks pretty sweet. SparkFun Electronics - USB3318 USB2.0 Transeiver IC
A lot of newer microcontrollers have the option of USB support built in now.
Is there something I'm missing? I didn't see anything about a programmer. I'm thinking there are other posts here that explain more about what he wants which is not a simple USB to serial interface.
As he specifically said parallel or serial, it seemed most likely that he was trying to connect a programmer - otherwise there's no point in mentioning parallel. If it's just data he wants to transfer, why not just use a cheap and simple USB/Serial converter - no need to mess about with SM chips.
Are you talking about USB to RS232 adapters? Because then you would need to level translate, which makes it more complicated. Getting a breakout board for an FT232R or making one yourself is just an easy way to plug USB into a breadboard and run RX/TX wires to your chip. You can also pull power from the USB supply that way as long as you are careful with it. The FTDI drivers have also come a long way and are pretty reliable now, you can also access the chip directly in your PC application rather than through a virtual COM port if you are doing an interface that's more complex than just streaming some debug or log data.
Cost effective IC which will give a parallel or serial output from the USB port... SO that i can interface with this by an external micro-controller......