Other Parts Discussed in Thread: REF5030, OPA350
Hi team,
Is it possible to use same supply for VREFH and VDDA, even when ADC is used? Or should I prepare separated line for VREFH?
Best regards,
Kurumi
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Hi team,
Is it possible to use same supply for VREFH and VDDA, even when ADC is used? Or should I prepare separated line for VREFH?
Best regards,
Kurumi
Kurumi-san,
While there will not be damage to the device if you do this, the ADC performance will be poor due to the in-accuracy of the VDDA supply compared to an external reference that is buffered. Not only will noise get coupled into the reference from the supply, but it will not be stabled compared to the above.
Please take a look at the schematic for the LauncPad for the F2837xD device for an example of the external ref circuit. https://dev.ti.com/tirex/explore/node?node=A__AFSa7NdB1y-Xl0dcjvxkhQ__c2000ware_devtools_package__FUz-xrs__LATEST
Best,
Matthew
Hi Matthew,
Thank you for the reply.
Please take a look at the schematic for the LauncPad for the F2837xD device for an example of the external ref circuit. https://dev.ti.com/tirex/explore/node?node=A__AFSa7NdB1y-Xl0dcjvxkhQ__c2000ware_devtools_package__FUz-xrs__LATEST
I believe external reference IC (REF5030) and buffer (OPA350) are used for generating ADC reference on the LaunchPad. As far as I understand, the expected issue is that VDDA might not accurate/stable enough to be used as ADC reference. If that is the case, then can we use same 3.3V for VDDA and VREFH, by placing additional bypass-capacitor and filter/buffer?
Best regards,
Kurumi
Kurumi,
That should work, although we have not tested with this configuration. Customer would need to make sure that the additional bypass cap/filter are sufficient for correct operation.
Best,
Matthew