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LAUNCHXL-F28P65X: What is the suggested VREF for 16 bit ADC

LIU QINGFENG
Prodigy 40 points
Part Number: LAUNCHXL-F28P65X
Other Parts Discussed in Thread: REF6230, REF5030, , TMDSCNCD28P65X

Hi,  Supporter.

 In the user guide of "C2000Tm F28P65x Series LaunchPadTm Development Ki“, It says “ This REF6230 is not a recommended reference for designs requiring  16-bit ADC operation”

But Ref6230 spec sounds quite good, initial accuray 0.05% and 3pmm Temp Coeff,  Sorry but don't catch why it is not suitable or not recommanded...

We actually plan to choose REF5030 which is more cost effective than REF6230..

Any specially attention should pay to achieve 16 bits ADC performance ? I don't expect the Vref as expensive as the DSP itself. 

Qingfeng.

 

  • 0
    TI__Genius 10876 points

    Hi Qingfeng,

    Thank you for reaching out. We chose to use the REF6230 on the LAUNCHXL-F28P65X because of the integrated buffer and due to the cost savings it provided over alternative reference IC + buffer solutions.

    We have not documented any issues with the performance of the REF6230 as the specs do match closely with our requirements. This note was added to the user guide because we saw that the reference IC + buffer solution cost has actually decreased in cost to where it makes sense to use that option over the REF6230, even considering the integrated buffer cost savings. We have collected plenty of data regarding 16-bit operation with the reference IC + buffer solution and are confident in its performance since it is used in past EVMs with 16-bit ADC. This is why in the schematic of LAUNCHXL-F28P65X, it says to refer to the TMDSCNCD28P65X for reference on designing the analog voltage reference circuitry

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    Prodigy 40 points

    Peter,

    Thanks, after read the spec of REF6230 again agree the Load regulation of ref will put thing in risk 

    Qingfeng

  • +1 in reply to LIU QINGFENG
    TI__Genius 10876 points

    Hi Qingfeng,

    Just wanted to provide an update to you.

    We have studied the REF6230 in greater detail and have concluded that it should be sufficient to provide analog reference. Our original warning was concluded after gathering preliminary setup in a very non-ideal scenario. We have done additional testing in a better setup and have seen much more comparable performance out of the REF6230 such that we can now recommend it and will be removing the warning in our documentation. 

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    Prodigy 40 points

    thanks for very useful update,Peter.