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How to choose power delivery system for 5V or 27V input

Mosi
Intellectual 735 points
Other Parts Discussed in Thread: LMZ13610, LM22670, LM22671, LM22678, LMZ31710

Hi

I'm developing a Kintex-7 FPGA board which has to work with both 5V or 27V input voltage. 

So far I couldn't choose appropriate power delivering system. I came up with LMZ13610 but then I realized it works with 6V input and higher. I'm not sure what could possibly happen if I gave it 5V. 

My voltages are 1.0V - 1.8V - 2.5V - 3.3V - 5.0V !

Now what do you think I should do? I want the board works with both 5V or 27V voltages by mounting or unmounting some components. 

  • 0
    TI__Genius 15810 points

    Hello Mostafa,

    You could use Webench to come up with a DC-DC regulator solution for your requirements. Webench is a free tool that takes your input voltage range, required regulated output voltage and load current and suggests a solution with caluclated BOM and schematic. For your requirements, I see that you could use the LM2267x family of parts from our simple switcher portfolio. the 'x' denotes the series number e.g. LM22670, LM22671, etc. 

    Here is a link to the product folder of the LM22678 (42V max input voltage and 5A max load current): http://www.ti.com/product/lm22678 
    On the right hand side you will notice a panel that asks you to enter your requirements. Once you click the 'open design' button, the software will search for various solutions and come up with something that you could use. I hope this information is helpful.

    Regards,
    Akshay

  • 0 in reply to Akshay Mehta
    Intellectual 735 points

    Thank you Akshay 

    Actually I need more output currents and I was looking for a high output current converter. The one that you mentioned seems to be good for wide input voltage range but not good enough fot output current

    Anyway what I did was using two converter in series. In case of supplying the board with 27V input I used one LMZ13610 (Input Voltage Range 6V to 36V and 10A output current) to convert 27V to 5V then I used 5 number of LMZ31710 (Input Voltage Range 2.95V-17V and 10A output current) to convert that 5V to other voltage rails like 3.3V 2.5V 1.8V 1.5V 1.0V

    But if someone wants to supply the board with 5V input then LMZ13610 will be bypassed and input 5V will goes directly to those 5 number of LMZ31710.

    Is this solution good enough? You know, using two converters in series ?

    Plus the first stage (LMZ13610) has 10A output current. Would that be enough for other LMZ31710 to make other voltag rails with 10A output for everyone of them?

  • 0 in reply to Mosi
    TI__Genius 15810 points

    Hello Mostafa,

    Would you send your schematic? If I understand this correctly, you have 5 rails hanging from 5V and all these use LMZ31710. And you have one LMZ13610 to convert 27V to 5V. This seems alright. But you have to make sure that the total load current from the outputs of the 5 LMZ31710 can be provided by the one LMZ13610. You could use the Webench Power Architect to give you a complete rail solution for your FPGA power. It has a comprehensive list of FPGA and you can find the one you are using from that list. Here is the link: http://webench.ti.com/webench5/power/webench5.cgi?app=powerarchitect&lang_chosen=en_US

    The solutions given by Webench will make sure that your primary rail can indeed provide for the loads on the secondary rail. I hope this helps.

    Regards,
    Akshay