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Hi Team,
I want to generate 1.2s(+/-20%) negative single pulse using NA555.
Do you have any example design such the one shot pulse generator using 555 timer?
If possible, I want to use positive edge of reset IC for the trigger of the one shot pulse and I'm looking for sample design now.
Regards,
Takashi Onawa
Hello Takashi,
When you say negative pulse. Do you mean a negative voltage pulse or negative edge pule as shown below? We don't have a spice model for the NA555. I used the TLC555 for demonstration.
Negative edge pulse:
Negative voltage pulse:
For a negative voltage pulse there is this circuit, however it doesn't provide a clean square pulse at the output and is harder to control the duration and voltage value. With this circuit I am unable to get the pulse to last 1.2sec. I don't believe this circuit is of use for your application but I wanted to show it for demonstration of generating a negative voltage pulse.
Negative Edge Pulse.TSCNegative Voltage Pulse.TSC
Best Regards,
Chris Featherstone
Hi Chris-san,
Thank you for your prompt response on this.
Here is the logic which they want to generate. Do you think it is realizable using 555 timer with some logics?
They want to generate 1.2s width negative pulse triggered by input positive edge.
Regards,
Takashi Onawa
Takashi-san,
Will the behavior shown below satisfy the requirement? The Vout out lasts approximately 1.2s. If the device is triggered while the output is low the device will not react until the specified time is complete in which case the next trigger event will create a low output for approximately 1.2s. I have attached the modified simulation below. If this looks good we can invert the input in order to achieve the signal drawn above. Let me know and I can work on that portion.
Best Regards,
Chris Featherstone
