DF221 is a static, master-slave, multiplexed scan D flip-flop. SET is asynchronous and active low. Output is unbuffered and changes state on the rising edge of the clock. Logic Symbol DF221 DS C SD SE Q Truth Table C ↑ ↑ ↑ ↑ X L D SD SE SN HX L H LXLH XHHH X LHH XXXL XXXH NC = No Change Q H L .