I am working on a project which require a high resolution of the output signal of L298N or similar driver. Is it possible to control the output signal with a 1% resolution or better? What is the typical resolution of such drivers?
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\$\begingroup\$ Can you create a triangular signal with 60 dB SNR immune from rise time impulse current EMI? Inside the same circuit? Do you know how to measure SNR in such a condition? \$\endgroup\$– Tony Stewart EE75Apr 22, 2022 at 13:57
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1\$\begingroup\$ 1% resolution is trivial. 1% accuracy is impractical through a 298, due to its drop and ton/toff times. Do you understand the difference between the two? Do you know what you need? \$\endgroup\$– Neil_UKApr 22, 2022 at 14:26
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2 Answers
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A resolution of 1% is 1 in 100 or less than 7 bits of PWM. This is not particularly ‘high’ resolution. Most microcontrollers should be able to generate such resolution at well over 20kHz.
As far as the L298 is concerned, it has a finite switching time and voltage drop. At higher PWM frequencies, the L298 switching time might cause significant error otherwise it can be ignored. It also has a voltage drop dependent on current. This would be another source of error.
You’d normally use a L298 to control a DC motor. If you wanted accuracy, then you’d have a means to sense motor speed/load and the control loop would seek to minimize the error. So unless you’ve controlling something really strange, the L298 as a source of error can be discounted.
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There is a difference between resolution and accuracy.
The driver isn't specified to have any particular accuracy, but you can look at the propagation delays and slew rates, and depending on the frequency you are using, you will be able to see that those delays will mean there is not a 1 % accuracy between input and output.
However, there is still a (nearly linear) relationship between input and output, so a 1 % resolution is possible.
