My experience comes entirely from Rainbird systems.

If yours is similar, you would need to install a "control zone" component to regulate the pressure to each system.

These adjust the pressure to conform the pressure to that required for a drip system. They also include a filter and controls for either electrical or manual operation.

Tom

If your pop-ups are Rain Bird 1800 sprinklers, the solution can be simple. Rain Bird sells a kit to convert an 1800 pop-up to a drip "control zone". The part number is RETRO-1800. You will also want caps to close off the other pop-ups on that zone. That part number is XC-1800. You should not run both drip and pop-ups on the same zone (off the same valve) you will be wasting a lot of water.

If your pop-ups are other than Rain Bird you should do what tdscpa suggested, buy a control zone for that zone and remove all the old pop-ups.