The BLK pin is used to sense the LLC DC input voltage (bulk voltage) level. The comparators on BLK pin have the following two thresholds:
A resistor divider is connected to the pin to achieve the desired system input range. A fault is triggered if BLK pin voltage drops lower than VBLKStop during operation. The detailed action of Input Under Voltage Protection is described in Input Under Voltage Protection (VINUVP) section.
Figure 33 shows the block diagram of the BLK pin.
BLK voltage is also used to monitor the input over voltage fault for some device versions as listed in Device Comparison Table. There are two thresholds:
When BLK voltage is higher than VBLKOVPRise, OVP is triggered; OVP gets cleared when BLK voltage falls below VBLKOVPFall.