LTC3780+AD5174

Hello! I make a charger for assembling 6S using LTC3780 and MCU STM32. To change the output voltage of the LTC3780, I use a digital rheostat AD5174. Part of the circuit with LTC3780 and AD5174 attached. In this form, this circuit does not work: the output voltage does not change. Individually, the digital rheostat is controlled (checked by deleting it from the circuit), the LTC3780 itself works as it should (connected a mechanical potentiometer instead of the AD5174 and the calculated value of the output voltage corresponds to the actually measured). Why don't LTC3780 and AD5174 work together?

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  • Hi Mikee

    The experiments revealed the following: if I set the output voltage with the AD5174 in advance,
    and then turn on LTC3780, then everything works. I checked it like this: I was flashing MCU with
    different firmware (for different output voltage / AD5174 value) and then running the firmware.
    At the same time, the RUN pin LTC3780 was distorted and the output voltage corresponded to the
    calculated one.
    Colleagues changed the value of resistance AD5174 ​​"on the fly" without resetting the LTC and the
    output voltage does not change.

    The output voltage does not change if I try to change the resistance value of the AD5174 with
    LTC3780 running.
    When replacing the AD5174 with a mechanical potentiometer of the same rating, circuit works.