High-side current source PWM control

Eren Seçkin

Hello,

I would like to implement a High-Side Driver controlled by PWM signal from a microcontroller: but with constant current through load. From the article High-side current sources for industrial applications , "A shunt regulator and a MOSFET" circuit (Figure 2 in article, image attached) seems to be fine for me. But, what I need is Vref being PWM signal. Thus, to control this circuit with PWM, where should I input my PWM signal at Shunt Regulator part (U1)? Or do I need to change the design or input the PWM from somewhere else?

Thank you,

over 3 years ago

0 Trailokya Rai over 3 years ago

TI__Genius 11401 points

Hi Eren

Scope of this topology is to provide constant current. you can look into figure 5 of the same app note for PWM controlled high side driver.

You can also go through app note - SLVAF10 . It address your problem exactly.

Regards

Trailokya

0 Eren Seçkin over 3 years ago in reply to Trailokya Rai

Prodigy 10 points

Hello Trailokya
Thank you for your response. What I need is that the current through load should be adjusted with a PWM signal but the adjusted current will be constant through the load. In other words, the current value should be adjustable, but after it is set, it should be constant through the load. Thus, it makes me think that maybe Vref should be the PWM signal to change the current value.
Regards

Eren

0 Trailokya Rai over 3 years ago

TI__Genius 11401 points

Hi Eren

If you apply PWM pulse directly on the VREF pin without feedback it will be in comparator mode and will not regulate. In that case VREF will not be established to provide constant current to RSET resistor. Hence you should not use this scheme.

Please look into app note - https://www.ti.com/lit/an/slvaf10/slvaf10.pdf?ts=1650308788989&ref_url=https%253A%252F%252Fwww.google.com%252F . It addresses your problem.

Regards

Trailokya

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High-side current source PWM control