NE555 precision timer output voltage, during simulation, happened to be different from datasheet Figure 13. Typical Astable Waveforms. Any ideas?
astable-NE555.7z (322.6 KB)
It happens. Live with it. Or use a data sheet from another supplier. Or a different NE555 model.
BTW, first time in my life I’ve heard the NE555 described as a “precision” timer.
Yes and make sure you are not expecting an original bipolar version to work like a CMOS version. Put a reasonable load on the output…such as resistor load of a few mA to ground.
Professional opinion: For a free running oscillator and some other NE555 type functions, I think you would do better doing it with a comparator. This is likely to be more accurate and maybe cheaper (for example 1 section of an LM339 quad comparator is hard to beat if you can use the other sections.) But the LM339 output is open collector, so coupling the output without upsetting the accuracy requires some care.
The key here is the word “typical”. Everything has variation.
Read the detailed specifications…
Oops, got it thank you.
Thank you for the load idea.
I suppose the idea of NE555 was to make times not dependent on supply voltage. I believe even 2x supply voltage change will give only small time changes (never checked it).
This can be the reason the word “precision” could be used.