ZHCSOY9 december 2021 UCC28781
PRODUCTION DATA
The CS pin is the current-sense input. The internal peak current control loop limits the highest magnetizing current, and Section 7.4.4 in this datasheet describes the peak current change in different operating modes.
The VS pin is a multi-function sensing input, which detects the input voltage, the output voltage, and the zero-current-detection (ZCD) through the auxiliary winding voltage, to optimize ZVSF performance and provide critical protections.
The FLT pin is a dual-purpose fault detection pin for either over-temperature protection or input over-voltage protection, depending on how the external circuit is configured.
The system protection functions of these three pins are introduced in Section 7.4.12.