FTDI FT232RL 3.3-5.5V USB to TTL Converter 

TheFT232RL Breakout Board Mini USB to TTL Converter is a great TTL converter for board compatible with Arduino. It uses a chipset Ft232rl USB power which has over current protection. It uses 500ma Self-Restore Fuse and is integrated with Rxd/Txd Transceiver Communication Indicator.

The FTDI FT232RL features fully integrated USB terminator. Fully integrated clock generation that does not require an external crystal, plus optional clock output selection that allows seamless interfacing to an external MCU or FPGA. Data transfer rate from 300 baud to 3 Mbaud (RS422, RS485, RS232) at TTL level. A 128-byte receive buffer and a 256-byte transmit buffer (with buffer smoothing technology) provide high data throughput