PMP41009: UCC28740-Q1

Hi,

I got some questions about UCC28740-Q1(Design reference PMP41009)

1. The recommended primary side ratio Nps of the transformer is 43.86,  But this means a too much primary inductance.  So can I use a lower Nps such as 18?

2. This excel warning as "Using a lower Nps than ideal may result in deeper DCM operation at max load and may result in lower efficiency". So what means "deeper DCM" and will this cause the circuit not to work properly?

Best wishes for you

Thank you