CD4052B: Spec difference between CD4052BPWR and TMUX4052PWR

The CD4052B is a much older device (originally made by RCA, then acquired by Harris and later by TI). The TMUX4052 is designed to be pin compatible, and has different but better characteristics. Both have clamping diodes at the I/Os; the TMUX does not have them at the control inputs to make them overvoltage tolerant.

Hi Vincent,

While the internal clamping diodes aren't explicitly drawn in the datasheet's simplified block diagram, they are active on the I/O pins. Their threshold is typically Vdd+0.5, at which point they forward-bias to protect the core logic.

Based on the provided schematic, the system VDD is 9V. Because the absolute maximum rating for the I/O pins is tied to VDD, applying a 10V signal exceeds the safe operating area (9.5V max before the diode turns on). The damage occurring at 10V happening seems to align with this violation.

Thank you,
Arya