I have this PWM exam preparation question in Computer Engineering where it says "What is one V_LSB?". However we've discussed nothing about LSB in the PWM section.

What does it means?

  • \$\begingroup\$ A byte size PWM signal has a least significant bit average voltage by duty cycle Vavg= 1/256 * Vdd perhaps is what they meant by V_LSB \$\endgroup\$ May 21 at 15:25
  • \$\begingroup\$ It is likely something your course has defined but unknown to the general public. The suggested assumptions are good and likely, but for a very specific and narrow view of PWM, which assumes your PWM period is fixed and only PWM on time can be altered. \$\endgroup\$
    – Justme
    May 21 at 15:44
  • \$\begingroup\$ LSB = least significant bit; MSB = most significant bit. But it might be byte instead of bit, depending on the context. In case you were asking about the "LSB" part. \$\endgroup\$ May 21 at 18:08

1 Answer 1


V_LSB means the voltage represented by 1 Least Significant Bit.

With a DAC, that means the output voltage change caused by an input binary value change of 1 - the smallest input binary change possible.

With your PWM, it will mean the change in output voltage from a low-pass filter driven by a PWM waveform, when the PWM changes by the smallest step its source circuit can produce.


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