He 74LS73 device contains two independent negative-edge-triggered J-K flip-flops with complementary outputs. The J and K data is processed by the flip-flops on the falling edge of the clock pulse. The clock triggering occurs at a voltage level and is not directly related to the transition time of the negative going edge of the clock pulse. The data on the J and K inputs is allowed to change while the clock is HIGH or LOW without affecting the outputs as long as setup and hold times are not violated. A low logic level on the clear input will reset the outputs regardless of the levels of the other inputs.
