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Automotive voltage regulator

Discussion in 'Electronic Design' started by [email protected], Aug 23, 2013.

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  1. Guest

    I have a need for 12V 250ma and 5V 1.2A outputs from car battery. Input voltage is clamped with TVS to <36V.

    The 12V output can go out of regulation during cranking but shouldn't shutdown during cranking.

    5V should be maintained even during cranking. This shouldn't be problem forany regulator with a drop put voltage of 1-2V.

    What I am looking at is to use a 12V buck regulator (may be LM2267X or LM2268X) and then another 12V to 5V buck regulator. What will be the output of adjustable buck switching regulator if the input voltage goes below the required output voltage? Will the o/p drop to zero or Vin - dropout?

    The other option is to use 5V 2A buck regulator and then 5V to 12V boost converter like LMR64010.

    Any suggestions? I am looking at cost and PCB real estate optimized solution.
     
  2. Guest

    The unit has a board/module inside which has operating range of 8V-12V and 5V is to the micro and peripherals. So operation down to 4V isn't really required.
     
  3. Guest

    There are several bucks that allow high duty-cycle operation. I have
    the same problem and have been using a TI TPS65320 for 5V. It's
    pretty cheap, works to 2MHz, and includes a free LDO (which switches
    from the input to the output when the buck turns on). As John points
    out, there are several boost/bucks around now. Some will operate the
    boost in pass-thru mode (boost shuts down) when the input voltage
    allows it. Look in the catalogs under the automotive parts. This is
    a very common need.
     
  4. IanM

    IanM Guest

    Have a look at system basis chips if you have a CAN/LIN requirement as well.

    Most are linear, there are some buck/boost versions but I don't know any off
    the top of my head.


    I have a need for 12V 250ma and 5V 1.2A outputs from car battery. Input
    voltage is clamped with TVS to <36V.

    The 12V output can go out of regulation during cranking but shouldn't
    shutdown during cranking.

    5V should be maintained even during cranking. This shouldn't be problem for
    any regulator with a drop put voltage of 1-2V.

    What I am looking at is to use a 12V buck regulator (may be LM2267X or
    LM2268X) and then another 12V to 5V buck regulator. What will be the output
    of adjustable buck switching regulator if the input voltage goes below the
    required output voltage? Will the o/p drop to zero or Vin - dropout?

    The other option is to use 5V 2A buck regulator and then 5V to 12V boost
    converter like LMR64010.

    Any suggestions? I am looking at cost and PCB real estate optimized
    solution.
     
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