Prevent child control inside the updatepanel to refresh the updatepanel

let say i have 2 UpdatePanels UP1 and UP2. Up1 contains a dropdownlist with 3000 items. When selectedindex of the dropdownlist is changed, it fires a partial postback to refresh the controls inside the UP2 which uses trigger. but at the same time it also refreshes the UP1which i want to avoid. and i also need this dropdown list to be inside the Updatepanel because the selected index is changing during partial postback.

Currently what i have done is i took this dropdownList out of updatepanel and the UP2 gets refreshed using trigger of that dropdownlist, and when it is required to update the the dropdown list i 'm injecting the javascript code in partial postback to do this.

any better work around to achieve this.

Thanks in Advance

RG

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