Cali. Vehicle Code 22450(a) reads:
"The driver of any vehicle approaching a stop sign at the entrance to, or within, an intersection shall stop at a limit line, if marked, otherwise before entering the crosswalk on the near side of the intersection.
If there is no limit line or crosswalk, the driver shall stop at the entrance to the intersecting roadway."
If the officers' only testimony is that you didn't "stop for 3 second", he has a problem because the statute does not specify an amount of time you must be stopped, it simply states that you stop.