Synchronous counter

Fig. 8-4: Synchronous counter, with JK-MS-FF in toggle mode

The negative clock transistion is the mechanism that toggles each FF. Therefore, whenever a Flip-Flop changes state, it toggles at exactly the same time as all the other Flip-Flops. In other words, all Flip-Flops change state in synchronism. This advantage needs an increase in hardware (additional gates), hence the asynchronous counter is the cheaper solution for time uncritical applications.