The LPC1800 microcontrollers feature a wide range of system functions including: a flexible 8-channel DMA for peripheral-to-memory, memory-to-peripheral, peripheral-to-peripheral, and memory-to-memory transactions, a low-voltage two-stage brownout detector which monitors the voltage on the VDD pins, power-on reset which can hold the device in reset until the operating voltage attains a usable level and a watchdog timer which can reset the CPU if software fails to periodically service it within a programmable time window. Additionally, each MCU has three Phase Locked Loops, one for the main clock, one to generate the 48 MHz required for the USB and a third for audio steaming over USB. Each PLL accepts an input clock frequency from an external oscillator and multiplies the lower frequency up to a higher frequency with a current controlled oscillator (CCO). Finally, there is a 12 MHz internal RC circuit that is 1% accurate over the entire voltage and temperature range, eliminating the need for an external crystal in many applications.