how to make textchanged event works when textbox place in update panel?

Dear All Experts,

Good day.

I have a textboxt which I set the autopostback to true. And when there is textchanged in the textbox, the textchanged event will fire and execute as per the codes i wrote.
It works well when i debug, however the autopostback make the webpage refresh each time the textchanged event is fired.

To prevent the page refresh, I move the textbox into a update panel. I found the textchanged event is not firing after I move the textbox into updatepanel.

What should i do to make the textchanged event fire?

thanks in advance for advice.

regards
garf