Using 2v caps in the place of a 2.5v cap

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  • spleenharvester
    Badcaps Veteran
    • Mar 2010
    • 893
    • UK
    #1

    Using 2v caps in the place of a 2.5v cap

    Hey all.

    I haven't really been able to get a clear answer on this - some people have told me it would work and some have told me it would not work.

    Basically, I wish to replace a low-ESR 2.5V cap in a CPU Vcore power section (one of those horrid NEC/Tokin OE907) with some low-ESR 2.0V tantalum caps.

    I've taken readings and the voltage doesn't rise above 1.2V (well, it powers a CPU, so if it reached 2.0V it would probably die very quickly). And considering many 2.0V caps are used for the same function in similar laptops, surely it would be fine?

    My worry is, would the lower max voltage mean it won't last long term? Will it be completely safe to use?

    Cheers
    Dell E7450 | i5-5300U | 16GB DDR3 | 256GB SSD
    Tags: None
    • gg1978
      Badcaps Veteran
      • Dec 2004
      • 431
      • USA
      #2
      Re: Using 2v caps in the place of a 2.5v cap

      It'll be fine with regard to the voltage.. I'm not sure what kind of ESR the NEC/Tokin part has however..

        Comment

        • spleenharvester
          Badcaps Veteran
          • Mar 2010
          • 893
          • UK
          #3
          Re: Using 2v caps in the place of a 2.5v cap

          Wonderful, cheers man.

          900uF 1.5mOhm, using 4x 330uF 6mOhm caps in parallel gives the same 1.5mOhm reading however.
          Dell E7450 | i5-5300U | 16GB DDR3 | 256GB SSD

            Comment

            • severach
              Badcaps Legend
              • Aug 2007
              • 1055
              • USA
              #4
              Re: Using 2v caps in the place of a 2.5v cap

              Get the datasheet on the PWM voltage regulator chip. For example, the highest voltage offered on the ISL6247 is 1.6000v making a 2.0v capacitor safe no matter what processor is installed. If you're certain that no other processor will ever be installed then your 1.2v measurement is valid.
              sig files are for morons

                Comment

                • Th3_uN1Qu3
                  Believe in
                  • Jul 2010
                  • 6031
                  • Romania
                  #5
                  Re: Using 2v caps in the place of a 2.5v cap

                  Yes, it will be just fine. Voltage derating is done so that the parts last longer - but since you are replacing a known problematic Tokin, it's pretty much guaranteed the replacements will last the whole working life left of this laptop, even if they're rated at just 2 volts.

                  Remember that 16v caps are routinely used for 12v rails and they hardly ever go bad if they're quality ones.
                  Originally posted by PeteS in CA
                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                  A working TV? How boring!

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