I have a UCC28600EVM-65W, I want to reduce the value of Rsu (R2 + R3 + R4) to reduce the start up time. I'm concerned about making the resistance too low, and dropping too much current through the internal zener diode on the Vdd pin.
I understand there is also a RC time-constant created by Rsu and "Csu" (C6).
Other than power dissipation of the Rsu, how should I determine the min value that Rsu can be? Absolute max current for the Vdd pin is 20mA. If I chose a resistor that kept Idd to say, 10mA or less, will everything be OK?
To get 10 mA would be an Rsu of 14.4k ohm (which would be consuming 1.44W)
Would that cause any problems?
Thanks,
Steve
