The CP2104 is a highly integrated USB-to-UART bridge controller providing a simple solution for updating RS-232/RS-485 designs to USB using a minimum number of components and PCB space. The CP2104 includes a USB 2.0 full-speed function controller, USB transceiver, oscillator, one-time programmable ROM and asynchronous serial data bus (UART) with full modem control signals in a compact 4mm x 4mm 24-pin QFN package. The on-chip one-time programmable ROM may be used to customize the USB Vendor ID, Product ID, product description string, power descriptor, device release number and device serial number as desired for OEM applications. Royalty-free Virtual COM Port (VCP) device drivers provided by Silicon Labs allows a CP2104-based product to appear as a COM port to PC applications. The CP2104 UART interface implements all RS-232/RS-485 signals, including control and handshaking signals, so existing system firmware does not need to be modified. The device also features up to four GPIO signals that can be user-defined for status and control information. Support for I/O interface voltages down to 1.8 V is provided via a VIO pin. In many existing RS-232 designs, all that is required to update the design from RS-232 to USB is to replace the RS-232 level-translator with the CP2104. Direct access driver support is available through Silicon Labs’ USBXpress driver set. See www.silabs.com/interface-appnotes for the latest application notes and product support information for the CP2104. Two evaluation kits for the CP2104 are available. The full-featured CP2104EK includes a CP2104-based USB-to-UART/RS-232 evaluation board with LEDs and RS-232 transceiver, a complete set of VCP device drivers, USB and RS-232 cables and full documentation. The CP2104-MINIEK is a low-cost kit that includes a small form factor evaluation board, mini USB cable, quick-start card, complete set of VCP drivers and full documentation.