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ADS7138-Q1: Reference Supply for ADC

AMEY KULKARNI
Prodigy 80 points

Part Number: ADS7138-Q1

Hello we are using ADC ADS7138QRTERQ1 in one of our application. In that application 5V is generated on another Board (5V supply is generated using Switch Mode power Supply) and then through connector it is brougt to base board where ADC is mounted. Same 5V Supply is used to power DVDD and then through Ferrite Bead and Capacitor to AVDD as shown below ((+5 ADC 1)):

So my query is , Is it the correct way to power the Analog Supply (AVDD)? Or should a Reference supply be used to have Good accuracy in ADC? Please let me know.

image.png

 

  • 0
    TI__Mastermind 20070 points

    Hi Amey,

    Sorry for the delayed reply. I was on Thanksgiving break here in the United States.

    I definitely do not recommend a switching regulator to power the ADC. As AVDD is also the reference voltage, it should be clean as possible (less than 1/2 LSB in error from the supply). Errors in AVDD directly affect the gain error, as PSRR is not good enough to significantly reject supply noise. A good LDO or voltage reference is recommended. 

    Regards,
    Joel