In powerline environments that have heavy capacitive loading close to the communication boards (e.g. a car battery), it may be beneficial to lower the transmit impedance of the PLC board by increasing the value of the coupling capacitors from 1uF and 0.47uF to 10uF and 10uF, respectively. This is shown in the attached schematics for C10 and C30.
Additionally, to increase the receiver impedance of the system, the RC filter input to the receiver can be changed to an RLC filter that is tuned to 132kHz. This is shown in the attached schematics for R52, C4, C5, and the addition of L5.
The schematics labeled “CY3273 RevStarStar Modified” have the potential improvements. The changes are circled in blue in both schematics.