With crystal-less operation, an external crystal is not required to operate USB full speed; Silicon labs patented clock recovery feature enables USB full speed to properly operate using the internal oscillator, delivering significant savings in space. In-system programming memory enables customization of USB vendor ID, product ID, product string description, power descriptor, device release number, interface string, device serial number and GPIO configuration without the need of an external memory. This memory is one time programmable and sizes vary depending on product. The CP21xx devices were specifically targeted for small 4 mm x 4 mm packages to meet the tight space constraint requirements necessary to enable portable solutions or to minimize the area impact when upgrading legacy serial peripherals to USB. The on-chip voltage regulator enables USB self-powered applications. The CP2101/2/3 can provide up to 100 mA @ 3.3 V and the CP2104/05/11/12 supplies 3.45 V to power a complete application. CP2110 and CP2112 connectivity bridges were specifically designed to support the HID-USB class specification which is natively supported in most operating systems. This means that companion CDs with driver information or high-maintenance download sites are no longer needed. In addition, HID-USB provides seamless compatibility with most operating systems which eliminates the product delays typically associated with solving compatibility issues, thus maximizing time to market and minimizing design effort.