*******************************************************************************************************
**
-----------------------------------------------------------------------------------------------
HOW TO USE THE SPREADSHEET
This spreadsheet will calculate for you the COMP pin cmponents to be used for a NCL30486 /30488 controller.
The zones underlined in pink need data from the user.
The zones underlined in yellow are calculation results.
------------------------------------------------------------------------------------------------
Typical line frequency:
Maximum output current:
Output voltage regulation target:
Estimated efficiency:
Output diode forward voltage:
Maximum output power:
Mosfet Coss:
Total Propagation delay time:
Use the NCL30488 Spreadsheet to calculate the parameters:
Primary Inductance:
Secondary to Primary turn ratio
Auxiliary turn ratio (Nauxp = Naux/Np):
Equivalent series resistor:
ZCD bridge upper resistor:
ZCD bridge lower resistor:
Calculate corresponding VCS setpoint:
We
Calculate power stage transfert function at full load:
Calculate power stage transfert function at light load:
For the light load calculation, we consider VREFX = 5% VREF
Frequency foldback dead time calculation:
(low line)
To simplify expression writting, define total dead-time:
Partial transfert function light load:
Chosse a crossover frequency such that the phase of the power stage has not turned
below -90°. For good performances, choose a crossover frequency below 20 Hz.
Target typically 10 Hz or lower
Define phase margin needed:
Power stage gain at Fc
Phase shift at Fc:
Needed phase boost:
Enter your value for R1C:
Place the zero at the power stage pole (full load):
C2C is selected to provide enough phase boost to compensate the light load phase shift:
Note : to filter correctly the 100 Hz ripple, it might be necessary to decrease the calculated fpC.
In this case, need to shift the crossover frequency lower.
Compensator Transfer function:
Open Loop Transfer function:
Full load:
Light load: