Hi,
Background: Our product design is based on UCC28722, during the first product launch we have used a Y capacitor C1 between VBUS and secondary ground to pass the conducted emission results.
Issue faced: The meter works from a control power supply 44V AC to 300V AC. The Y capacitor forms a leakage path from the primary to the secondary side which interferes with our Voltage measurement. The voltage measurement is a high impedance network and any leakage path from this supply causes to display voltage even if the measurement inputs are cut off. In our next revision we need to eliminate the Y capacitor and still achieve the conducted emission performance ( CLASS A as per CISPR 11).
Support from TI: We need TI to suggest appropriate front end and layout modifications to achieve the CE results without Y Cap. Today without Y CAP the product fails by ~ 6dB for CLASS A requirement.
Once someone responds on this E2E query I will PM the schematics.
Regards
