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DRV103: DRV103 doesn't change output voltage

Youssef Nassar
Prodigy 70 points
Part Number: DRV103

Hi, I am youssef Nassar,

i am using DRV103 to control a 12V proportional valve using uC, i get a pwm signal from the uC to an RC circuit to make it analog and connect it to the duty cycle Adj pin, which has a range from 1.3 to 3.9V.

The problem is that when I change the pwm value (as a result it will change the value of the analog voltage to pin 1), the output voltage is always 12V. I don't know if this is normal or not or if the output pin will always give 12V but vary in the current. i haven't try it yet on the valve i only measured the voltage from the output pin with no load.

So I would like to know if this is normal or if i am doing something wrong.

Thanks in advance.

  • 0
    TI__Genius 10855 points
    Hi Youssef,

    Thanks for reaching out on E2E!

    Please refer to Figure 2 in the datasheet. To my understanding, you're PWMing a 12V signal and seeing 12V on the output of the device. This is the correct mode of operation, since the PWM simply changes the width of the signal.

    Let me know if you have any additional questions!

    Thanks,
    Arthur Huang
  • 0 in reply to Alpha H
    Prodigy 70 points
    Hi Arthur, Thank you for your reply! I understand that PWM change the width of the signal but isn’t it supposed to have an average value depending on the duty cycle? And this average value must appear when i measure it with a multimeter. ( for example if i gave to the duty cycle adj pin a voltage of 1.5V the output duty cycle must be 10% of the time which if i measured the output pin i must see 1.2 V on the multimeter as it is the Vrms or average value). Please correct me if i am wrong. Thanks again.
  • 0 in reply to Youssef Nassar
    TI__Genius 10855 points
    Hi Youssef,

    Ultimately, this will be dependent on your multimeter if it can measure Vrms. The easiest way to measure this sequence is taking a scope shot on an oscilloscope.

    Thanks,
    Arthur Huang