Autocomplite define the size of the list

Hi Experts,

I use sapUi5 autocomplite control and I use also the secondery value,sometimes the secondery value is long

and the listbox is becoming larger then the textBox(the autocomplite control) I dont want it,I want the if the value is long

still not exceed  the size of the text box control ,how should I define it?

Best regards,

Stephane