freetextbox is postback or refreshed with asp.net timer

have wrapped up the freetextbox editor inside updatepanel but it still keep refreshing maybe caused by timer tick,

tried enablepartialrendering="true" inside script manager wont make difference

<asp:Timer ID="FieldTimer2" runat="server" Interval="1000" OnTick="FieldTimer2_Tick" /></ContentTemplate><Triggers><asp:AsyncPostBackTrigger ControlID="FieldTimer2" EventName="Tick" /></Triggers></asp:UpdatePanel>
...<asp:UpdatePanel ID="udpfreetextbox" runat="server"><ContentTemplate><FTB:FreeTextBox id="FreeTextBox1" runat="Server"  /></ContentTemplate></asp:UpdatePanel>