LM5023: Datasheet Example file simulation in TINA

Hello Jacob, 

Let me answer the lower questions first.
-  The lower frequency calculation result for FREQ_LL at equation (25) is wrong, as you suspect.  Clearly it is a typographical error since simply working through the equation using the values shown results in 45.92 kHz, similar to your Mathcad result.

-  In your Mathcad Datasheet Example file, your result for R1 is the same as the datasheet equation (45) result.  However, your calculation of R2 value uses 20V for Vaux_ovp, but the Performance Specifications in Table 1 (page 21 of datasheet) lists Output OVP to be 24V.  Working equation (51) with 24V_ovp results in R2 = 5.05kR.   
Since the value of Cd in equation (54) depends in part on RFF (= R1||R2), if R2 is incorrect, then Cd result will also be incorrect. 

About the TINA-TI simulation file:
I do not have access to the TINA program so I can't open the sim file to see what you are asking about. 
I can suggest that the LM5023 TINA model may have simplified functions compared to the actual device and it may have a higher turn-on threshold at the QR pin than the 0.35V listed in the spec table.  

Also, the external Cd value is intended to delay the ringing signal to QR a specific amount of time so that the QR voltage falls below 0.35V just at the same time that the actual ringing reaches the minimum valley voltage.  If Cd is too small, then the delay time (t_dlyqr) will be too small and the MOSFET will turn on too soon. 
Try increasing your C8 value in the simulation until it achieves valley switching. 

Regards,
Ulrich

Hi Jacob, 

I am trying to have someone else look at the simulation.  However I will be out of office for the next several days.
I will close this thread now and revisit when I come back.

Regards,

Ulrich