ZXBM5210 (PWM DC motor controller) question

[mribble]

My question is about what Vref does for this part.  I want it to rage the PWM duty cycle between 0% and 100% approximately linearly (though I don't care if it's not exactly linear) as Vref increases.

I plan to run this at 5V and on page 10 there is a graph of output duty vs Vref voltage that acts kind of like I want.  On page 3 it says the min Vref voltage is 3V.  Is that a typo or can someone explain what that 3V is supposed to mean?

Here is the datasheet. https://www.mouser.com/datasheet/2/115/ZXBM5210-335426.pdf

I've also attached a schematic of how I plan to use this part.  If anyone has any suggestions I improvements I'm open to suggestions.  Thanks for your feedback!

[mvs]

I plan to run this at 5V and on page 10 there is a graph of output duty vs Vref voltage that acts kind of like I want.  On page 3 it says the min Vref voltage is 3V.  Is that a typo or can someone explain what that 3V is supposed to mean?

It is a bit strange spec. On "OutputPWM Duty vs VREF/VDD Ratio" chart you can find a curve for 3V supply, which is senseless if min Vref voltage is also 3V.
You may contact Diodes inc. tech support to clarify this.

[Doctorandus_P]

I did a small search for Vref in the datasheet. and then, on page 5 found:
In the forward or reverse mode, for VREF speed control, the output drive duty ratio is generated internally based on the voltage on the VREF pin

Which is as I expected.
I've seen something similar with a PT4115, which is a cheap SMPS LED driver. The output can be controlled directly via PWM, or with an analog voltage, and in that case the chip generates it's own PWM internally.

[Terry Bites]

The controller has two modes, internal or external PWM. See table on page 5 of data sheet. Tie Vref to Vdd (100% Duty) for external PWM.