The I2C Fast mode (400 Kbit/s) specification states that glitches 50 ns or less should be filtered out of the incoming clock and data lines. The input glitch filter performs this function by filtering glitches on incoming clock and data signals. Glitches shorter than the glitch filter length are filtered out. The glitch filter length is defined in terms of APB interface clock cycles and configurable from 3 to 21 APB interface clock cycles. Input signals are synchronized with the internal APB interface clock.