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ADS127L01: One ref for 12 ADC

Darren Jenkins
Genius 11896 points
Part Number: ADS127L01
Other Parts Discussed in Thread: REF6033, , REF6030

Data converter team,

We have a customer who likes the performance of the ADS127L01, and is putting 12 of them on a board.  What would be the impact of using a single REF6030 or REF6033 for all 12 ADS127L01?

Can or should this be done?

Thanks,

Darren

  • 0
    TI__Mastermind 43550 points

    Hi Darren,

    The REF60xx family cannot drive the DC input current of 12 ADS127L01 reference inputs.

    Depending on the CLK frequency, the reference input impedance of ADS127L01 will range between 2.2kohm (CLK=16MHz) and 4kohm (CLK=4MHz).  The REF60xx family is rated for 4mA max.  

    A quick calculation using the REF6030 (the maximum external reference voltage is 3V) and 12 ADS127L01's operating at 4MHz:

    Iload=12*(3V/4k) = 9mA

    I suggest using a single reference, such as REF5030, and adding a reference buffer for each ADC, similar to Figure 118 in the datasheet.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    TI__Genius 11896 points

    Thank you very much, Keith.  I have a follow up question I'll post separately.

    Darren