Power supply help

Discussion in 'The Projects Forum' started by awwende, Feb 14, 2012.

  1. awwende

    Thread Starter Active Member

    Feb 17, 2009
    I'm working on a project to make an adjustable power supply controlled by an arduino. Since the arduino doesn't have a DAC built in, I'm using a two stage RC filter to convert the PWM to DC to control the output voltage and a second PWM with a comparator to limit the current.

    My overall design goal is to have a 20-40W supply capable of going up to 20V. I'm going to end up characterizing boost regulators with it and will need to supply 2.2V @ 9A. What scares me though is to be able to have 20V output I'll need Vin to be maybe 24V, so I know the LT3083s will be dissipating quite a bit of heat.

    How efficient is the LT3083? I've looked at the datasheet and they do have a high efficiency, high current circuit but the output voltage is only 10-12V. Is there a buck converter that has a voltage set pin rather than just using a voltage divider to the feedback pin? Or would I have to use a digital pot to control the output voltage?
  2. crutschow


    Mar 14, 2008
    All linear regulators have the same efficiency. It's simply equal to the ratio between the output voltage and the input voltage.

    Don't know of any buck regulators with a voltage set pin. They all need feedback from the output to regulate the voltage. You should be able to use a digital pot to control the voltage as long as the pot voltage limit is met.