Quad transparent latch in the 4000B family
The CD4042BPW is a quad D-type transparent latch from Texas Instruments' 4000B series, containing four independent latches each with a 1:1 circuit configuration and differential outputs (Q and Q-bar). It operates across a 3V to 18V supply range and is specified over the full military temperature range of -55°C to 125°C, making it suitable for industrial and aerospace environments where wide voltage margins and temperature extremes are the norm.
Timing and drive — what the 40 ns and 6.8 mA mean on the bench
The 40 ns propagation delay sets the maximum data rate through the latch — at 3V supply the delay is at its longest, so the actual toggle rate into a downstream load will be lower than the bare 40 ns suggests, especially when driving the rated 6.8 mA output high or low. The 6.8 mA output drive is typical for the 4000B family at 5V; at 18V supply the drive current increases, but the propagation delay also shortens — the timing closure at the receiver depends on the actual supply rail and load capacitance, not just the datasheet typical.