The CD4042BD is a quad D-type transparent latch from the 4000B CMOS logic family. Each of the four independent latches captures the D input when the clock is high and holds it when the clock goes low, with complementary Q and /Q outputs available on every channel. The differential output pair saves an external inverter when the design needs both true and inverted versions of the stored bit — a common need in synchronous counter decoding, bus-hold registers, and state-machine feedback paths. The 4000B series is known for its wide 3V to 18V supply range, which lets this latch operate directly from unregulated battery stacks, 5V logic rails, or 12V industrial supplies without a local regulator. Propagation delay is 40ns typical at 5V, so the part comfortably handles clock rates up to about 12 MHz in a 5V system — adequate for control logic, panel interfaces, and slow sensor buses. The 16-SOIC package (3.90 mm body width) is a standard surface-mount footprint shared with many 4000B and 74HC series parts, simplifying PCB layout reuse.
Supply voltage and temperature — the design envelope
The 3V to 18V supply range is the defining feature of the 4000B family. At 3V the latch draws minimal quiescent current (microamps) and is suitable for battery-backed registers; at 12V or 15V the noise margin improves, and the output drive current rises to 6.8 mA source and sink at 10V. The 40ns propagation delay is specified at 5V — expect roughly 20ns at 10V and 80ns at 3V, following the typical CMOS speed-versus-voltage curve. No derating is needed for ambient temperatures up to 125°C, though the package power dissipation must be respected — the 6.8 mA output current at 125°C junction is the practical limit for continuous drive.
The 4000B series has been a staple logic family for decades, and TI continues to manufacture these parts for industrial and defense customers who value the wide supply range and broad temperature grade. ROHS3 compliance is confirmed, so the part meets the latest EU restriction directives.