issue about adjust frequency of PWM in SG3525A

Hi all,

I simulated a PWM output with SG3525A model, but i meet an issue that the PWM's frequency is controlled by the period of parts proterty, but not by Ct, RT and RD (pin 5,6,7). that means no matter how to adjust the values CT, RT or RD, the PWM's frequency doesn't change. So could someone please tell me how can i adjust the frequency of PWM via Ct, RT and RD (pin 5,6,7), but not with the period value in the parts proterty ? of cause, in orcad capture Pspice.

Thanks very much in advance! :)