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LM5145: Digital control of Feedback LM5145

k.kral
Prodigy 180 points
Part Number: LM5145
Other Parts Discussed in Thread: LM5141,

On Picture is LM5141, which has been brought into the feedback over resistor add output of DAC.  How does it work?

If DAC is 0V is Vout set on max for example 25V , If DAC is on max for example 2.5V is Vout on 0V..

it's simple and allows you to digitally control the output voltage.

Question is, this can also be used to control the output current?

LM5145 works on 250kHz ie. 4us clock.

ADC measure current -> MCU compare it with required -> MCU Set DAC -> DAC slew = total 2.5us

Yhat is, one control intervention each clock cycle.

My question will work or be a problém?

  • 0
    TI__Mastermind 25590 points
    k.kral,

    Theoretically, this would work to adjust the output voltage. Note: If you set the output voltage, the output current will be dependent on the load. So with a fixed load, you cannot regulate voltage AND current at the same time.

    You can adjust the maximum current, meaning you regulate the voltage until you reach that current, then regulate the current. But this is already set with ILIM and RILIM.

    -Sam
  • 0 in reply to Samuel Jaffe
    Prodigy 180 points

    Of course, it is not possible to regulate both voltage and current at the same time.

    The source could function either as a source of constant current or as a source of constant voltage.

    I'm rather concerned whether it is hoped that the regulating loop described by me will be stable in the constant current mode to the load at with load resistance changes.

    it must clearly be tried, but I'm a qualified guess if it's worth trying

  • 0 in reply to k.kral
    TI__Mastermind 25590 points
    k.kral,

    I've spoken to our expert and we agree that it's possible but may be difficult. You will have to look out for stability.

    -Sam