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DIGITAL CONTROL OF LM2576HV-ADJ OUTPUT.

devi lal saini
Prodigy 30 points
Other Parts Discussed in Thread: LM2576

DEAR SIR/MADAM

I WANT A VARIABLE DC POWER SUPPLY FROM 2VDC TO 40VDC USING LM2576HV-ADJ AND DAC E.G MCP4921. CAN U HELP ME THAT HOW CAN INTERFACE DAC AND LM2576HV-ADJ. I MEAN HOW I CAN DIGITALLY CONTROL THE OUTPUT OF LM2576HV-ADJ SO THAT I CAN CHANGE THE OUTPUT DIGITALLY DURING RUNNING OF CIRCUIT. IF U HAVE A ANOTHER CHEAP AND BEST SOLUTION THEN TELL ME FOR A VARIABLE DC  OUTPUT 2-40VDC WITH 3AMP/5AMP CURRENT OUTPUT LOAD SO THAT WE CAN CONTROL OUTPUT DIGITALLY BY MICROCONTROLLER.

REGARDS 

DEVI LAL SAINI

  • 0
    TI__Genius 16025 points

    Hi Devi,

    I'm looking into you request and will get back to you shortly.

    The LM2576 doesn't have PMBus or any digital control element to it. Let me see what I can come up with.

    Thanks,

    Anston

  • 0 in reply to Anston Lobo
    TI__Genius 16025 points

    Hi Devi,

    While it is not recommended to use a DAC as a feedback control mechanism, it is nevertheless possible.

    The DAC would need to be connected in place of the GND contact for the bottom feedback resistor all else being the same. As the voltage from the DAC increases, the output voltage drops and vice versa if the DAC voltage drops to zero.

    Please bear in mind that this does not tackle the correct compensation of the part for all cases.

    Thanks,

    Anston

  • 0 in reply to Anston Lobo
    Prodigy 30 points
    Can we control output of lm2576hv-adj using digital pot like ad8400 and microcontroller.
  • 0 in reply to devi lal saini
    TI__Genius 16025 points
    Hi Devi,

    It is hard to estimate what the parasitics are using a digital pot. This is an important consideration for correct compensation of the circuit. Most resistors have very very small capacitances or inductances associated with them making them ideal for a feedback choice, however a digital pot has relays and is configured to behave on any external input.

    This is certainly possible but I'm afraid testing across the operating input and output range is the only way to guarantee operation.

    Thanks,
    Anston