I need 1 USB to many RS232 Convertor?

I've an embedded system with Linux running on an ARM9 MCU and i need to design an interface card to communicate with cards like 7816 smart cards. I can only use USB interface of the system and i can communicate with cards via rs232 protocol. do you have any idea to convert USB port of this sytem to many RS232 intarfaces without using a MCU like unit. i thought about using a USB Hub IC, and many USB- RS232 convertor ICs connected to its downstream ports. but this would be so complicated. may be somebody can suggest a more intelligent solution like a more useful IC or any other components. I also can use EMIFA bus of the ARM9 but it's more difficult to use for me. thanks for your attention