The clock system on F20xx devices is very similar to what was just discussed in that there is an LFXT1 oscillator, a DCO, a clock distribution tree and the same clock names. However, a few enhancements have been made. Minimum pulse-width filters that prevent any fast glitches from getting through and over-clocking the CPU have been added along with an enhanced DCO capable of running 16 megahertz to support the higher speed of the 2xx devices. Finally, a third oscillator has been added called the VLO (Very Low Frequency Oscillator). In this case, it runs at approximately 12 kHz and is a very low-power, on-chip, low-frequency oscillator intended to be used in applications that do not need crystal accuracy but do need low-power standby mode. As shown here, the VLO is used in place of the LFXT1 oscillator and enables the Low Power Mode 3 standby current consumption of the 20xx devices. In fact, using the VLO in place of the 32768 LFXT1 oscillator further reduces current consumption. Also, improved DCO temperature stability and accuracy (± 2.5%) are achieved. The DCO calibration method mentioned prior for the 1xx basic clock is still applicable for the 2xx devices and can function in the exact same way. However, the 2xx device DSO temperature stability is better than the 1xx, so the calibration routine may not need to be run as often.