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12v 12A regulator with only one chip!!!!!

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  • 12v 12A regulator with only one chip!!!!!

    Hi everyone, im spanish and i have spended a considerly amount of money in my car-pc without making it works properly. i have a p4 in an atx motherboard and a bought the m2-atx to power it, the problem came later when this power supply arrived to my house. The pc couldnt start becouse there werent enough power on the 12v rail (atx12v connector, needed---> 7A minimum only for the celeron).

    Then i thought i could connect to this connector another power supply only for regulate the 12v, but this was a hard task. i found very unefficient and big circuits but finally i found the LTC3780 chip that was specified to drop about 5A on the 12v with the buck-boost metod with the 6-30Vin. Searching for a made circuit to build it i discovered that there is a circuit called dsx12v with only this chip that could drop 12A at 12v!!!! wow, with the chip designed only for 5A.

    I have looked for this way of configuration for that current but i found nothing nothing. The only things i know is that they used the IRLR7833 power mosfet this chip and some caps.

    I would like to recieve some help from someone who know something about electronics to build my circuit. Please i have to do it work

    Here are some notes for the LTC3780 chip. that can be ordered as sample in www.linear.com. i have 2 of them
    Datasheet
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    Thanks for your attention

  • #2
    Change rsense and mosfet. Read datasheet 5 times, you'll find the answer
    - Will work for Bandwith -

    Comment


    • #3
      You will need to lower the value of the Rsense so the current limit is increased. The MOSFETs can be paralleled to handle the increased current.

      Watch out for the inductors values and Peak/RMS current rating. You will also need to get better capacitors, one with lower ESR. Again paralleling them will do but will obviously increase the board size.

      If you only need around 10A one off PSU, then you can just use those power module, search the forum. Parallel them to get the required current rating. You can get free samples of them.

      Comment


      • #4
        Originally posted by didiet78
        Change rsense and mosfet. Read datasheet 5 times, you'll find the answer
        5 times? I read it 50 times

        Some of the stuff in there are not so clear, there are a few conflicts as well.

        Comment


        • #5
          Originally posted by Chris31
          You will need to lower the value of the Rsense so the current limit is increased. The MOSFETs can be paralleled to handle the increased current.

          Watch out for the inductors values and Peak/RMS current rating. You will also need to get better capacitors, one with lower ESR. Again paralleling them will do but will obviously increase the board size.

          If you only need around 10A one off PSU, then you can just use those power module, search the forum. Parallel them to get the required current rating. You can get free samples of them.


          For mosfet, i thing IRLR7833 will do. You don't have to paralleled.

          For 10A 2 paralled ltc3780 (at 5A like in Datasheet) like mastero psu did
          - Will work for Bandwith -

          Comment


          • #6
            confused

            Thanks very much but i dont understand on what depend the inductor. In this desing the value is diferent.
            And are there any other values to change, resistors and values of caps or others?
            how can i get the low esr caps? and how low they have to be?
            Thanks
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            • #7
              Originally posted by Chris31
              If you only need around 10A one off PSU, then you can just use those power module, search the forum. Parallel them to get the required current rating. You can get free samples of them.
              How can i do this?

              Comment


              • #8
                Originally posted by zaccaro

                Then i thought i could connect to this connector another power supply only for regulate the 12v, but this was a hard task. i found very unefficient and big circuits but finally i found the LTC3780 chip that was specified to drop about 5A on the 12v with the buck-boost metod with the 6-30Vin. Searching for a made circuit to build it i discovered that there is a circuit called dsx12v with only this chip that could drop 12A at 12v!!!! wow, with the chip designed only for 5A.
                Do you just want a DSX12V power supply rather than going through all the trouble?

                Jeff
                MPEGBOX - Plexiglass Computer
                www.mpegbox.com

                Comment


                • #9
                  Originally posted by zootjeff
                  Do you just want a DSX12V power supply rather than going through all the trouble?

                  Jeff
                  I know that this is easier but I have spent 100€ (120$) in one psu and the money doesnt rain. I prefer to look for another solution. In case it cannot, it will buy it.

                  By the way zoojef, are you the man who designed the dsx12v circuit?

                  Comment


                  • #10
                    Originally posted by zaccaro
                    I know that this is easier but I have spent 100€ (120$) in one psu and the money doesnt rain. I prefer to look for another solution. In case it cannot, it will buy it.

                    By the way zootjeff, are you the man who designed the dsx12v circuit?
                    Yes I am the designer, www.mpegbox.com is my website. I designed the DSX12V DSX12VD and the DSATX as well as the uSDC20D and MPBS1.

                    You'll spend much more than 120$ in building your own board. Even if you get most of the parts for free..

                    The DSX12V is like 75 dollars.

                    -Jeff
                    MPEGBOX - Plexiglass Computer
                    www.mpegbox.com

                    Comment


                    • #11


                      Do it yourself if you confident with your skill. Or built bobblick's solution, it use single chip too . You'll find in evandude website and bobblick site
                      - Will work for Bandwith -

                      Comment


                      • #12
                        Originally posted by didiet78


                        Do it yourself if you confident with your skill. Or built bobblick's solution, it use single chip too . You'll find in evandude website and bobblick site
                        I have seen these solutions but them dont reaches the current i need. Thanks anyway

                        Comment


                        • #13
                          Originally posted by zootjeff
                          You'll spend much more than 120$ in building your own board. Even if you get most of the parts for free..
                          i'll agree there. by the time you buy a bunch of parts (particularly the high-quality electrolytic capacitors you should be using, and the inductors of course) you might be surprised at how much you have spent, ESPECIALLY if you start blowing up some of your parts and having to buy extras... and when you have to redesign and rebuild your circuit several times to get it working properly... both of which are very likely to happen. Not to mention having to consider whether significant amounts of your time are worth anything to you.

                          Perhaps you might also do well to reconsider the processor you are using... 7 amps minimum on the 12v rail is 84 watts, which is INCREDIBLY high for just the processor for use in a car PC system. If you are really determined to use a very power-hungry system like that in a car, then you need to be prepared to spend the big bucks powering it (ie - you probably should have bought a DSATX instead of an M2-ATX), or live with an inverter. Honestly, I don't think a processor that uses over 84 watts has ANY place in a carPC system. Obviously you're free to do what you want, but I think you're beating your head against a wall trying to power that system without spending much money.
                          But don't take it from me! here's a quote from a real, live newbie:
                          Originally posted by Viscouse
                          I am learning buttloads just by searching on this forum. I've learned 2 big things so far: 1-it's been done before, and 2-if it hasn't, there is a way to do it.
                          eegeek.net

                          Comment


                          • #14
                            Originally posted by evandude
                            i'll agree there. by the time you buy a bunch of parts (particularly the high-quality electrolytic capacitors you should be using, and the inductors of course) you might be surprised at how much you have spent, ESPECIALLY if you start blowing up some of your parts and having to buy extras... and when you have to redesign and rebuild your circuit several times to get it working properly... both of which are very likely to happen. Not to mention having to consider whether significant amounts of your time are worth anything to you.

                            Perhaps you might also do well to reconsider the processor you are using... 7 amps minimum on the 12v rail is 84 watts, which is INCREDIBLY high for just the processor for use in a car PC system. If you are really determined to use a very power-hungry system like that in a car, then you need to be prepared to spend the big bucks powering it (ie - you probably should have bought a DSATX instead of an M2-ATX), or live with an inverter. Honestly, I don't think a processor that uses over 84 watts has ANY place in a carPC system. Obviously you're free to do what you want, but I think you're beating your head against a wall trying to power that system without spending much money.
                            I am in agreement with you, but to return back now after all the effort which I take already inverted, making the box of the motherboard, the motherboard micro atx that I only bought for the car-PC, and the celeron I bought thinking that this kind of procesors consumed less…jajaja stupid… At the moment I am going to try to make the voltage regulator since several pieces have arrived me or on the other hand i will think what to do. by the way, knows somebody if I can directly feed the connector atx12v with the battery on the car? perhaps the current splitters accept some variation of voltage, isnt it?

                            Comment


                            • #15
                              well if your processor is the problem then you could probably buy a lower-speed celeron that used a lot less power, for less money than building or buying a 12v power supply to supplement it. I don't know what setup you have (and i'm not an intel guy anyway) but just a quick search revealed a number of celerons around 2ghz or so for only $20-30 on ebay.

                              Originally posted by zaccaro
                              knows somebody if I can directly feed the connector atx12v with the battery on the car? perhaps the current splitters accept some variation of voltage, isnt it?
                              as crazy as that sounds at first, on second thought it seems almost plausible. Before I say anything, DISCLAIMER: i'm not responsible for anything you blow up.
                              But the 12v line feeding the processor goes to regulator circuitry that generates the much lower core voltage of the CPU (a couple volts or so)... so it's POSSIBLE that these regulator circuits can operate with a wider input voltage range than the 12v ATX specs. After all, a typical buck regulator type of circuit is generally good as long as the input is a volt or two above the output. However, for efficiency purposes there is a very good chance they designed it in a way that it can't work off a wide input range. I guess it's one of those things that could be possible but I wouldn't want to risk my own system to find out
                              But don't take it from me! here's a quote from a real, live newbie:
                              Originally posted by Viscouse
                              I am learning buttloads just by searching on this forum. I've learned 2 big things so far: 1-it's been done before, and 2-if it hasn't, there is a way to do it.
                              eegeek.net

                              Comment

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