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I want to use J/K trigger and I was told that usually IC outputs need pull-up resistor, but if I understand it correctly the following J/K trigger is based on CMOS: TI J/K trigger And it seems to me that CMOS is capable of making both low and high signal, so there is no need for pull-up resistor, right?

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    \$\begingroup\$ All CMOS inputs which are not constantly driven high and low, need a pull-somewhere-resistor. \$\endgroup\$ – rdtsc Dec 11 '15 at 17:06
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    \$\begingroup\$ @rdtsc the OP is talking about an output pull-up resistor not an input pull-up. Answer - the 4027 doesn't need a pull-up o/p resistor but some CMOS gates do so always check. \$\endgroup\$ – Andy aka Dec 11 '15 at 17:14
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There is no need for a pull-up or pull-down resistor on CMOS outputs (unless they are open-drain). Inputs should always have a pull-up, pull-down or be connected a valid logic level (another output or a supply rail, usually).

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The datasheet for the CD4027B does not indicate that the outputs are open-drain. Therefore no pull-up resistor to a DC power source is needed at the output.

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