SN54LS68

The SN54LS68 is a type of dual 4-bit decade counter. The SN54LS68 has two clock pins. Clock 1 is for the A flip-flop, while clock 2 is for B, C, D flip flops. Counter one can perform bi-quinary counting. All clocks trigger on the high-to-low transition of the clock pulse.

Features of SN54LS68 are: (1)heavy duty outputs IOL rated at 8mA/16 mA; (2)counter one has individual clicks for A flip-flop; (3)direct clear for each 4-bit counter; (4)guaranteed maximum count frequency is 40MHz.

The absolute maximum ratings and recommeded operating conditions of the SN54LS68 can be summarized as: (1)su pply voltage: 7V; (2)input voltage: 7V;(3)operating free air temperature range:-55 to 125; (4)storage temperat ure rang:-65 to 150. Recommended operating conditions: (1)supply voltage: 4.5V min, 5V typ and 5.5V max; (2)high-level input voltage: 2V min; (3)low-level input voltage: 0.7V max; (4)high-level output current:-1 max; (5)low-level output current: 8mA max; (6)clock frequency: 0MHz min and 50MHz max; (7)pulse width: 25ns min; (8)clear ina ctive state set-up time: 25ns min, etc.