SNVAA88 December 2023 LM51581-Q1 , TPS1H000-Q1 , TPS92642-Q1
The differential supply noise level is measured directly between the Dout+ and Dout- pins of the serializer and has direct impact on the FPD-Link back channel performance. The noise limit for FPD-Link III is 25 mVpp in the frequency range of 0 – 50 MHz. To correctly measure the differential supply noise, both the serializer and deserializer need to be powered down by pulling the PDB pins low on both devices. Figure 4-8 shows the noise level with pulsing LEDs.
The measured noise level is 20 mVpp, which is below the mentioned limit of 25 mVpp specified for FPD-Link III.