UCC28070 PFC CONTROLLER
Equations #28 & #29.
The below line statement states “The output capacitor maximum low-frequency, zero-to-peak, ripple voltage is closely approximated by:”
Question #1) Is zero-to-peak ripple voltage correct or what should it state ?
EQUATION #28
Using the design values listed in TI UCC28070 WORKSHEET: Pinavg =5300Watts, Voutavg = 390V, f2LF = 120Hz, Cout = 3240uF and solving for unknown ”V0pk”, my solution is “5.496V”.
Question #2) Is “5.496V” the correct voltage for “V0pk”?
Question #3) IF “5.496V” IS NOT the correct voltage for “V0pk”, THEN WHAT IS THE CORRECT VALUE FOR “V0pk”?
Question #4) THEN WHAT IS THE CORRECT EQUATION FOR “V0pk”?
Question #5) Is there any information that is required to determine the correct value of “V0pk” that I have not asked.
EQUATION #28
To solve for “Vsense” “Kr” needs to be solved.
Kr = Rb/(Ra+Rb)
Using the design values listed: Ra = 3Mohms, Rb = 23.2Kohms and solving for unknown ”Kr”, my solution is “.07674.
Now back to solving for “Vsense”, ”V0pk” = 5.496V and ”Kr” = .007674 and solving for unknown ”Vsense”, my solution is “0.0421V”.
Vsense = 5.496 x 0.007674 = 0.042176
Question #6) Is this the correct voltage for “Vsense”?
Question #7) IF “5.496V” IS NOT the correct voltage for “V0pk”, THEN WHAT IS THE CORRECT VALUE FOR “V0pk”?
Question #8) THEN WHAT IS THE CORRECT EQUATION FOR “V0pk”?
Question #9) Is there any information that is required to determine the correct value of “V0pk” that I have not asked.
