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LM5175: Variable output with FB control

na na78
Guru 16770 points
Part Number: LM5175
Other Parts Discussed in Thread: PMP20410

Hi

We are considering to control VFB to keep output current as 4A, using PWM signal from MCU.

Do you have a reference design such that VFB is controlled PWM signal?

We attached way of use to be assumed.

Can you give me some advice?

BestRegards

  • 0
    TI__Guru 69285 points

    What you have drawn will work if you use an analog signal instead of PWM.  If you use a PWM signal

    you will need a filter to smooth out the pulses.

  • 0
    TI__Mastermind 21720 points
    Hello,

    PMP20410 has an output adjustment pin. A filter could be added onto the front end to filter the PWM signal into an analog control voltage.

    Above you say that the output current needs to be 4A. Are you trying to create a constant output current controller? If not what is the variable output voltage range?

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Guru 16770 points

    Hi Frank

    Thank you for your reply.
    I understand what you mean is a way of using like DAC out (analog signal) and filter will be required.

    Hi Garrett

    Thank you for your reply.
    We are considering variable voltage for constant output current. 

    The input 6.4V to 12.6V is assumed.  The output range is 3V to 20V, and 9.6V as typical.

    Regarding to output voltage, can we use the following blog to calculate output voltage?

    How to dynamically control the output voltage with a COT regulator

    TI E2E support forums
    Constant-On-Time (COT) regulators provide a simple , cost-effective way of implementing step-down buck regulators with nearly fixed frequency. COT regulators do not require loop compensation and provide excellent transient performance with minimum design...


    BestRegards