SLUSD49A September 2017 – January 2019 UCC256303
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
BW pin senses the output voltage through the bias winding and protects the power stage from over voltage. The nominal output voltage is 12 V. The bias winding has 3 turns, and the secondary side winding has 2 turns. So the nominal voltage of the bias winding is given by:
The desired OVP threshold in this design is 115% of the nominal value. The OVP threshold level in UCC256303 device is 4 V, so the nominal BW pin voltage is given by:
Choose the lower resistor of the BW resistor divider to be 10 kΩ.
The upper resistor can be calculated by: