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Thread: Two power regulation options, which would you do?

  1. #1
    Variable Bitrate therussman2002's Avatar
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    Two power regulation options, which would you do?

    Option 1:
    - Using however many diodes it takes to drop the voltage from a trunk battery (isolated from the starter system) by 2 volts (so 13.6 - 15.whatever will be 11.6-13.whatever)
    - pumping this power into the pw200v power supply that accepts 11-14volts
    - advantage: theres 12amps max on the 12v rail, my processor requires 10.116amps on the 12 rail (max) (and i have a 3.5" hd and a xenarc to power)
    - disadvantage: hooking up a bunch of $1 diodes doesnt sound too reliable, i'd imagine i'd have to spend some money to make sure my car doesnt fry my psu

    Option 2:
    - Using that keypower 250w power supply that handles whatever voltages the car will throw at it
    - advantage: no under/over voltage issues at all
    - disadvantage: only 10amps max on the 12v rail (12amps peak), but my processor requires 10.116amps max (and i have a 3.5" hd and a xenarc to power)

    I have been reading and searching and reading some more, and I cant seem to find a solution. The opus150w only had 5amps, 6.5 peak on the 12v rail.

    My last resort, it seems, is to sell off my 2.8 northwood and buy a lesser processor

  2. #2
    Variable Bitrate therussman2002's Avatar
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    or whats wrong with this?

    http://www.digikey.com/scripts/DkSea...310180&Site=US

    4v-36v input, adjustable output, 20amp current output, and for $6? whats the deal

  3. #3
    Constant Bitrate RPI Geek's Avatar
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    Quote Originally Posted by therussman2002
    or whats wrong with this?

    http://www.digikey.com/scripts/DkSea...310180&Site=US

    4v-36v input, adjustable output, 20amp current output, and for $6? whats the deal
    IANAEE (I Am Not An Electrical Engineer), but what's wrong with it is the very first line on the data sheet:
    Vout = 1/2 Vin (Supply Splitter)
    Old plans out the window because of an accident .
    Have: M1-ATX, EPIA M10000, 256MB, 60GB 2.5", slim slot load DVD
    Need: Time, HU integration, ideas for Lilli

  4. #4
    Variable Bitrate therussman2002's Avatar
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    yeah, i just did the 'live chat' with the digikey people:

    whatever i posted is just a controller to operate other components to do the work stated

    so thats worthless but he directed me to part # LT1084CP-12, which is the highest-current voltage regulator they carry (5amps at 12volts)

    supposedly i can have 5 of these in parallel, with their heat dissipated into the metal 'puter case when screwed to it.... but then, thats a good 40-50 bucks (but still cheaper than that keypower psu that lacks sufficient current on the 12v rail)

  5. #5
    Variable Bitrate therussman2002's Avatar
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    heres a link to another question i had in another thread:
    http://www.mp3car.com/vbulletin/show...153#post350153

    turns out this isolator i wanted to buy may regulate things well enough, i'll probably just try it out and see (in a week or so)

  6. #6
    Constant Bitrate RPI Geek's Avatar
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    Quote Originally Posted by therussman2002
    yeah, i just did the 'live chat' with the digikey people:

    ...

    part # LT1084CP-12, which is the highest-current voltage regulator they carry (5amps at 12volts)

    supposedly i can have 5 of these in parallel

    ...
    Did the Digikey people tell you this? I've been watching discussions on putting power regulators in parallel, but no one was really sure if it was possible.
    Old plans out the window because of an accident .
    Have: M1-ATX, EPIA M10000, 256MB, 60GB 2.5", slim slot load DVD
    Need: Time, HU integration, ideas for Lilli

  7. #7
    Variable Bitrate therussman2002's Avatar
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    yeah digikey told me all that i posted above about those regulators

  8. #8
    FLAC
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    Quote Originally Posted by therussman2002
    but he directed me to part # LT1084CP-12, which is the highest-current voltage regulator they carry (5amps at 12volts)

    supposedly i can have 5 of these in parallel
    Whilst you can put regulators in parallel (some of the spec sheets even have circuits), the drop out voltage may be the killer for you. 1.3V for the part you've listed.

    I originally had the diode plan but after measuring my car voltage I found the variation was too big (peak ~14.6V; dropped below 13V in long traffic jams!).
    ATX spec is +-5% or 11.4-12.6V.

    Now I'm planning to use multiple regulators in parallel but of the ultra low drop out (0.4-0.5V) variety. I need 12-15A total I believe. Will be measuring it shortly.
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

  9. #9
    Newbie Dirk9N's Avatar
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    what about these parts: http://www.linear.com/pc/productDeta...40,C1055,P1279

    that are Low Dropout Positive Fixed Regulators. I use two of them to regulate the 14.4V from the Car to the 5V needed from the USB devices.
    U just need cooling part and two Caps (like shown in the datasheet)
    thats the complete circuit:



    U just need to set three of them Parallel. If U use the 7.5A Types, you get 22.5A as permanent maximum at peaks there is more possible.

    You can request samples or bye them at www.linear.com for example.

  10. #10
    FLAC
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    These offer very large currents which means only a few need to be bought but at full output the datasheet shows you're still at 1.3V dropout voltage. That may not matter. I'm concerned about it as I'm building a combined tank + 12V regulator circuit and the tank voltage is driving my decisions (drops rapidly below 12v due to the current my mAtx system will draw).
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

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