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(Un) precision 4.096 vrefs — Parallax Forums

(Un) precision 4.096 vrefs

Erik FriesenErik Friesen Posts: 1,071
edited 2009-07-22 13:22 in General Discussion
I bought a few mchip 4.096 vrefs a while back, and installed them in my project. I decided to check them for accuracy, all of them are a bit off, as in one of them reads 4.122mv per my fluke 179. I suppose this is within specs, but it sure seems like I could do better. Anyone else found a good one?

Comments

  • Tracy AllenTracy Allen Posts: 6,666
    edited 2009-07-22 03:28
    The one at 4.122 has 0.64% error, assuming the Fluke is right (DC volts ~ 0.1%)

    I can recommend the LT1790-4.096, which comes in 0.1% or 0.05% accuracy grades. SOT23-6 package.

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    Tracy Allen
    www.emesystems.com
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-22 03:30
    You get what you pay for. The MAX6241A, for example, boasts an output tolerance between 4.095V to 4.097V, but they're not cheap. For something in between that and the Microchip parts, search "reference" on www.digikey.com and pick the tolerance you need.

    -Phil
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-22 07:52
    wow. MAX6241AESA+ 0.02% error $13.70

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  • Erik FriesenErik Friesen Posts: 1,071
    edited 2009-07-22 11:04
    The max is a little more than I need. Looks to me like the LT1790 will fit the bill though.

    The mcp1541 datasheet gives them 1%, so they are in specs.

    I had just naively assumed that a precision reference was precision, and 1% hardly deserves to be labeled precision.
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-22 13:22
    percision means percise with in error outlined in spec sheet. It costs more to make something more accurate and not everyone needs 0.02% accuracy.

    Think of it this way. I can bend a half inch pipe into a square in a minute if you don't care that the ends line up perfectly. If you want it to be a perfect square to the mm I will need to do some precision measurements and tweek my bends to get them perfect. May take half hour.

    At least you learned a valuable life lesson. Read the datasheet and look for the infomation that is important to you(I.E. error factor)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    propmod_us and propmod_1x1 are in stock. Only $30. PCB available for $5

    Want to make projects and have Gadget Gangster sell them for you? propmod-us_ps_sd and propmod-1x1 are now available for use in your Gadget Gangster Projects.

    Need to upload large images or movies for use in the forum. you can do so at uploader.propmodule.com for free.
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