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How to generate a 5 MHz clock with 50 percent duty cycle? I have an application that requires a continuous clock signal to operate. 555 timer is an easy option but it generates only up to 1 MHz frequency. I know that there are various crystal oscillators available but not sure how to connect.

The application is for a printer. The data is loaded into the printer ICs clock signal is high and with a constant frequency of 5MHz.

I need to design a clock generator to load this data into the ICs. The interface connector has 2 input pins, one for data and the other is for clock signal.

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    \$\begingroup\$ I think 50% duty cycle for a 555 might be problematic so, what are your real requirements? \$\endgroup\$
    – Andy aka
    Oct 13, 2020 at 10:43
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    \$\begingroup\$ Just buy a crystal oscillator module that outputs a square wave \$\endgroup\$
    – Dirk Bruere
    Oct 13, 2020 at 10:50
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    \$\begingroup\$ Iomesh - Hi, you said: "there are various crystal oscillators available but not sure how to connect." You're not sure how to connect the oscillator to what? You haven't told us anything about your design yet. Please edit your question and explain the context e.g. what is the application? Can you add a schematic (or at least part) showing relevant components? What exactly is the problem with connecting a crystal oscillator? Do you need a standard logic-level clock signal (e.g. 5 V / 3.3 V), or something different? The more detail you add, the better any answers will be. Thanks \$\endgroup\$
    – SamGibson ♦
    Oct 13, 2020 at 10:56
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    \$\begingroup\$ I think you need to consider your data source as well as the clock. Just clocking along at 5MHz won't do you much good if your data bits are changing other rates. Also, that "NZ385-512" makes nervous. That implies a lot of stuff connected to the clock. \$\endgroup\$
    – JRE
    Oct 13, 2020 at 12:35
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    \$\begingroup\$ What is sending the data and does it have a clock of its own? \$\endgroup\$
    – ocrdu
    Oct 13, 2020 at 12:35

1 Answer 1

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A clock oscillator module requires no more than power connections with a bypass capacitor to produce a square wave output at approximately 50% duty cycle (for example, 45-55% guaranteed). You just need to pick one that is suitable for your desired frequency, supply voltage, output type and accuracy/stability. There may be an enable input that needs to be tied to an appropriate logic level.

If that is insufficiently close to 50% duty cycle, you can procure an oscillator that operates at double your desired frequency (10MHz in this case) and divide the output with a flip-flop, such as 74HC74.

For example, the ECS-5032MV-100 which is a 10MHz oscillator which operates from 1.6 to 3.6V Vdd, plus a 74ALVC74.

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