(1) Concerning Figure 4 on page 9 of the UCC28C4X/UCC38C4X datasheet: What is the purpose of the resistor in between the COMP pin and the REF pin? What value (or range) is suggested for this resistor.
(2) Concerning Figure 4 on page 9 of the UCC28C4X/UCC38C4X datasheet: Is the gate pull-down/keep-off resistor required? This is the resistor between the gate of Q1 and ground.