16-SOIC footprint and board-fit
The SN74LS378D is a single-element, 6-bit D-type flip-flop with positive-edge triggering and non-inverted outputs, housed in a 16-SOIC package (0.154" width, 3.90 mm body).
40 MHz clock and 27 ns propagation delay — what they mean for timing closure
The 40 MHz maximum clock frequency sets the upper limit for the data toggle rate. The 27 ns max propagation delay at 5 V and 15 pF load is the time from clock edge to output valid — budget this into the worst-case timing path. At 40 MHz the clock period is 25 ns, so the propagation delay consumes the entire period; the part is usable at that frequency only if the downstream setup time is zero or the clock is stretched. Quiescent current is 22 mA typical; the output drive capability is 400 µA source and 8 mA sink at the rated logic levels.
Active production and compliance documentation
The part is ROHS3 compliant.