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Possible use with variable output?

Category: Datasheet/Specs
Product Number: LTC3779

Dear All,

Just asking a hypothetical question here - has anyone ever tried using one of these devices with a relatively constant input voltage, and created a variable output voltage? The potential use case we're considering would require 44-52V input with 30V-100V output at around 50A maximum; maximum power output in the 3kW range.....we would feed the voltage feedback error amplifier with a variable voltage generated by a DAC to control Vout. I have seen MCU to SMPS controller links via I2C, but nothing I have found has the voltage/current capability we would need.

Thanks for any suggestions.

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  • Hello,

    Yes, in principle this is possible with the LTC3779, because the controller regulates its VFB pin to a 1.2 V reference, so you can make the output voltage programmable by altering the feedback network. Your approach with DAC is similar to using a variable resistor. I would recommend to use our existing simulation tool such as LTspice and LTpowerCAD to simulate your intended circuit design to see how the controller behaves when VFB is injected with DAC.

Reply
  • Hello,

    Yes, in principle this is possible with the LTC3779, because the controller regulates its VFB pin to a 1.2 V reference, so you can make the output voltage programmable by altering the feedback network. Your approach with DAC is similar to using a variable resistor. I would recommend to use our existing simulation tool such as LTspice and LTpowerCAD to simulate your intended circuit design to see how the controller behaves when VFB is injected with DAC.

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