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Ramp UP Ramp Down using PWM for DRV8842(TMS320F28075)

sanath rai
Genius 3875 points
Other Parts Discussed in Thread: TMS320F28075, DRV8842

Hello,

I am working on TMS320F28075 and i am generating a PWM of 7KHz and  i am getting analog input signal(0-3.3V) to my ADC channel(12 bit).

According to the input signal(ADC) i am varying my PWM from 0 to 100% linearly and driving my solenoid through DRV8842.

1) According to our requirement i need to control the Ramp UP and Ramp Down signal (0 to 5secs) individually.

How do i achieve the above requirement ?

2)How do i set Imax and Imin value independently in DRV8842?

Regards,

Sanatn Rai

  • 0
    TI__Guru** 114905 points
    Hi Sanath,

    I am not sure I understand your question fully. What ramp up and ramp down signal are you trying to control?

    I am assuming you are using a PWM to generate a reference voltage, and using VREF to control the current. There are several methods to control Imax and Imin in the DRV8842.

    Method 1: Set the sense resistor and I[4:0] to achieve Imax when VREF is maximum. The reference voltage can be applied to the VREF pins to control the percentage of current.

    Method 2: Set the VREF and sense resistor to control Imax and use the I[4:0] bits to control the percentage of current. This method is limited to the settings available.
  • 0 in reply to Rick Duncan
    Genius 3875 points

    Hello Rick,

    Sorry for the delayed reply.

    My first Question was How to add Ramp Up Time and Ramp Down Time  parameters to our Analog input Signal that is to my PWM ,which i am varying linearly according to the Input signal(ADC 0-3.3v).

    For further Understanding the above scenario the following diagram will help you.

    Please go through the following diagram and give us your suggestion

    Regards,

    Sanath Rai