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CD4050B: On power down, the output goes high momentarily

Jeffrey Lu
Prodigy 30 points
Part Number: CD4050B
Other Parts Discussed in Thread: SN74AHC367

When Vdd supply (3.3V) is removed, it has been observed that the outputs momentarily goes high (~1.5V)  for a few milliseconds and back to 0V.

The inputs of the buffer are 3.3V signals coming from an FPGA.

The outputs do not have any pull up/down resistors on them. 

  • +1
    Guru 283290 points

    The minimum recommended supply voltage is 3 V. Below that, correct operation is not guaranteed. (And CD4000 devices are optimized for high voltages like 20 V.)

    To disable the outputs during power up/down, use a device with /OE like the SN74AHC367.