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AM2634: Can ADCs support 3.3V VREF?

Matt Calvo
Genius 14775 points
Part Number: AM2634


Hey Sitara team,

I have a customer evaluating the DRV3256+AM2634 for a new project and we are wondering if the ADCs in the AM2634 can still be used with a 3.3V VREF. I looked at the datasheet and it looks like the latest revision noted down the following: "Updated ADC VREF Operating Voltage from 3.3 V to 1.8 V"

The DRV3256 datasheet specifically recommends that the ADC reference voltage be used for AREF and the accepted range is 3.3-5V so if we could use VREF as 3.3V that would be great. If VREF only supports 1.8V then we might not be able to use it for the DRV AREF and would probably have to use a discrete ADC.

Do you have any guidance on this?

Best regards,

Matt Calvo

  • 0
    TI__Mastermind 24613 points

    Hey Matt,

    Apologies for the delayed response here.

    The AM263x does use a 1.8 V reference for the ADC, but this is internally scaled to support 0V-3.3V ADC input signals. The AM263x ADC VREF signal can also use an internal (3.3 -> 1.8V) LDO that operates on the VDDA3V3 rail. This allows designers to implement cheaper and simplified power distribution networks. Alternatively, a dedicated high-precision, low-noise 1.8 V reference can be provided to the AM263x device to meet system requirements.

    I did take a look at DRV3256-Q1 Integrated 3-Phase 48-V Automotive Gate Driver Unit (GDU) with Advanced Protection and Diagnostics datasheet (Rev. B) and could not find any clear limitations that would cause incompatibility with AM263x. What analog signal is expected to be measured with the AM263x ADC?

    Best Regards,

    Zackary Fleenor

  • 0 in reply to Fleenor
    TI__Genius 14775 points

    Hey Zack,

    Thanks for the info!

    I am going to move communication on this support topic to email with the BLDC Apps team member looped in so that this can be addressed collaboratively. There is still some confusion on how to properly interface the two chips.

    Best regards,

    Matt Calvo