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AM6548: OPP voltage vs frequency

Ryuuichi machida
Guru 11515 points
Part Number: AM6548
Other Parts Discussed in Thread: TPS62363, INA226

Hello,

I would like to confirm about below.

* Now, we have GPEVM of AM654x. According to schematic of this EVM, VDD_MPUx come from output of TPS62363. And this have following note.

"Default Output voltage is set to 1V"

Actually, when I checked voltage by reading INA226 register value, output voltage indicate 1.0025V.

On the other hand, according following wiki page, TI evaluate EVM using 800MHz as CPU clock.

http://software-dl.ti.com/processor-sdk-linux/esd/docs/latest/linux/Release_Specific_Performance_Guide.html 

Now, we have following question.

* According 5.4 Recommended Operating Conditions, there is following description.

– OPP_NOM: 0.9 V – 1.1 V
– OPP_OD: 0.9 V – 1.2 V
– OPP_TURBO: 0.9 V – 1.24 V

On the other hand, according to table 5-2, voltage range is defined as shown below.

Now, TI use 800MHz as CPU clock, so min voltage of VDD_MPU should be bigger than 1.06V.

However, VDD_MPU voltage of EVM is 1.00V in fact.

So, could you please confirm which condition is correct information ?

Best Regards,

  • 0
    TI__Guru 72605 points

    Hello Ryuuichi,

    The power section of the Data Sheet was updated in December 2019. Please use the power values in the latest Data Sheet. I will check to see if our latest software was updated to match the Data Sheet.

    The latest Data Sheet says the voltage should default to 1.1V for OPP_NOM. Based on the AVS value that is programmed in eFuse, software could then adjust that voltage to something in the range of 0.9V - 1.1V.

    There are two unknowns here:

    1) eFuse value: early AM654x chips might not have the eFuse AVS value programmed. So the AM654x part on your EVM may or may not have an AVS value. In that case, the voltage should stay at the nominal value.

    2) AVS software: I do not know if the current software accounts for AVS, or if it just sets the voltage to the nominal value. I will check.

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    TI__Guru 72605 points

    Hello Ryuuichi,

    Ok, as of Linux Processor SDK 6.2 we have not updated the software to match the datasheet. I am trying to get updates in for SDK 6.3, but I cannot guarantee that the software will be updated by then.

    The OPP settings are in uboot, drivers/power/mfd/k3_avs.c . You can manually modify the default voltages to match the datasheet by searching for am654_vd_data , and then adjusting .volt for AM6_VDD_MPU0 and AM6_VDD_MPU1.

    The current software reads the AVS registers. If the AVS registers are unprogrammed, then it sets the voltage to the default values specified in k3_avs.c

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    Guru 11515 points

    Hello Nick-san,

    - 1 -

    Ok, as of Linux Processor SDK 6.2 we have not updated the software to match the datasheet. I am trying to get updates in for SDK 6.3, but I cannot guarantee that the software will be updated by then.

    The OPP settings are in uboot, drivers/power/mfd/k3_avs.c . You can manually modify the default voltages to match the datasheet by searching for am654_vd_data , and then adjusting .volt for AM6_VDD_MPU0 and AM6_VDD_MPU1.

    Do you mean that user should need to change following default voltage to 1.1V in case of OPP_NOM ?

    - 2 -

    The current software reads the AVS registers. If the AVS registers are unprogrammed, then it sets the voltage to the default values specified in k3_avs.c

    When I checked status register of DEVINFO and OPPVID. Any VD domain do not support AVS. And also, OPPVID register shows zero for all domain.

    - 3 -

    Based on the AVS value that is programmed in eFuse, software could then adjust that voltage to something in the range of 0.9V - 1.1V.

    According to datasheet, Range of "0.9V - 1.1V" will be supported in case of "without AVS". So I would like you to re-confirm about above.

    What my question is why min value of Table 5-2 is less than case of "without AVS".

    I believe that Table 5-2 show fuse register value for AVS.

    Best Regards,

  • 0 in reply to Ryuuichi machida
    TI__Guru 72605 points

    Hello Ryuuichi,

    I apologize for the delayed response.

    -1- Updates to file k3_avs: Please see the attached zip file. 0001-power-mfd-k3_avs-update-am65xx-MPU_VDD-voltage-value.patch shows the updates you are asking about. 0002-arm-dts-am654-Bump-up-MPU-speed-to-1GHz.patch shows how to change the OPP setting in uboot. Note that as of SDK 6.2, the software team has only run tests at 800MHz. I do not expect to see software errors at higher core frequencies, but we have not tested to make sure.

    3731.am654-Bump-up-MPU-speed-to-1GHz.zip

    -3-

    As of the December 2019 version of http://www.ti.com/lit/ds/symlink/am6548.pdf (Rev I), the "Recommended Operating Conditions" table states that the AVS Voltages will be within the range of 0.9-1.1V for OPP_NOM, 0.9-1.2V for OPP_OD, and 0.9-1.24V for OPP_TURBO. Section "Voltage and Core CLock Specifications" show the OPP voltages without using AVS.

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    Guru 11515 points

    Hello Nick-san,

    Sorry for my late response.

    For -3- :

    I understood that sentence of note of "Recommended Operating Conditions" is mistake.

    For - 1- :

    I will check attached code later.

    Best Regards,