What does the on-resistance of a MOS tube relate to?

Do you know what the on-resistance of a MOS tube is related to?

Many people first think of the Vgs drive voltage.

But is it really that simple?

In fact, the on-resistance of the MOS tube is not only related to Vgs, but also to the Id current.

We often see this line of parameters in data sheets.

What this means is that when the Vgs driving voltage is 10V , the maximum value of the on-resistance is 3.5Ω, and when the Vgs driving voltage is 4.5V , the maximum value of the on-resistance is 6Ω. We can see that the ID current here is 0.22A.

 Generally, a Rdson curve graph is given: the vertical axis is the on-resistance and the horizontal axis is the ID current.

 It can be seen that when the Vgs driving voltage remains unchanged , as the ID current increases, Rdson will also increase. When the Vgs voltage is low, Rdson will become steeper due to the change in ID current.

That is to say, if the ID current remains unchanged and the Vgs driving voltage increases, the Rdson of the MOS tube will become smaller, which means that the heat generated by the MOS tube will be smaller .

Therefore, in some situations where large currents are controlled, the driving voltage of Vgs needs to be appropriately increased.

We can use push-pull drive to make the driving current larger, and the MOS tube will be turned on and off faster.