If they are refreshed often, your users will see more ads when they’re on the same screen. This is good in that they see more ads, but can also be very annoying.

In the XML entry for your AdMob banner, just add this attribute to set your refresh rate to 60 seconds, as an example:

app:refreshInterval="60"

AdMob only allows you to have a refresh rate between 12-120 seconds

The complete XML element for the AdMob banner should look something like this:

<com.admob.android.ads.AdView
	android:id="@+id/ad"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	app:backgroundColor="#000000"
	app:primaryTextColor="#FFFFFF"
	app:secondaryTextColor="#CCCCCC"
	app:keywords="@string/admob_keywords"
	app:refreshInterval="60"
	android:layout_gravity="bottom"
/>