3.5.2.4 Digital Preemphasis

The PLL loop bandwidth of the ATA8510/15 is 50 kHz, which limits the transmission data rate to about 20 kHz Manchester or 40 kHz NRZ if the FSK modulation is enabled. To achieve higher data rates, a digital preemphasis filter is integrated that can be enabled by setting the FSEN.PEEN register bit to ‘1’. The data stream is resampled at approximately 2 MHz by this filter, which introduces a jitter on the symbol time of about 2% at 20 kBit/s Manchester (40 kBit/s NRZ), 4% at 40 kBit/s Manchester (80 kBit/s NRZ), 6% at 60 kBit/s Manchester (120 kBit/s NRZ) and 8% at 80 kBit/s. There are no additional settings associated with this filter.