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AM623: AM623 and AM62L SDIO voltage control

GR
Genius 3066 points
Part Number: AM623
Other Parts Discussed in Thread: AM62L,

Tool/software:

Hello,

My customer is testing AM623 and AM62L.

In the AM62x EVK, I believe it support both boltage mode 1.8V and 3.3V.

Question 1 (AM623)

Is Selecting 1.8 or 3.3V automatically from SoC? (SoC's I/O controller select voltage domain automatically?)

If yes, it should switch VDDSHV_SDIO voltage.

It mean "If SoC detect high speed capacity, SoC's driver will communication to PMIC for change voltage?"  

https://www.ti.com/lit/ug/spruj40c/spruj40c.pdf 

Question 2 (for AM62L)

Does AM62L has same SDIO hardware to AM62xx?

Could you let me know if there is difference in voltage control?

Thanks,

GR

  • +1
    TI__Guru 62215 points

    The AM62Lx device has an internal LDO circuit called SDIO_LDO that is controlled by MMCSD1 host controller. SDIO_LDO is used to source VDDSHV3 when connecting an UHS-I SD Card to the MMC1 port, where the initial IO operating voltage of an UHS-I SD Card is 3.3V and changes to 1.8V when switching to one of the higher speed modes. This internal SDIO_LDO allows the MMCSD1 host controller to change the VDDSHV3 operating voltage associated with the MMC1 signals at the same time it tells the SD Card to change its operating voltage.

    The system design must connect the internal SDIO_LDO output pin named "CAP_VDDSHV_MMC" to the appropriate decoupling capacitor and the VDDSHV3 power pins.

    The SDIO_LDO input pin (VDDA_3P3_SDIO) should be connected to same 3.3V power rail that is used to power the SD Card, and that 3.3V power rail needs to have a power switch in the path so the SD Card power and SDIO_LDO power can be turned on/off at the same time when needing to reset the SD Card. The switch needs to be controlled by the AND function of power-on reset, warm-reset, and a GPIO so the SD Card can be power cycled anytime it needs to be reset because cycling power to the SD Card is the only way for it to be reset. The VDDSHV3 power rail needs to cycle on/off at the same time as the SD Card since the IOs associated with both devices are not fail-safe. This is why the SDIO_LDO that powers VDDSHV3 need to be connected to the same 3.3V power rail that sources the SD Card.

    The AM62x device does not include the SDIO_LDO function, so a similar function must be implemented on the PCB with the PMIC or other components. I'm not familiar with the PMIC capabilities, so not able to comment on how it can be used to implement this function. However, someone recently pointed out a concern with the AM62x EVM PMIC implementation. I seem to recall the AM62x EVM implementation was not performing the expected power sequencing of the AM62x IO power rail (VDDSHV5) at the same time as the SD Card. If so, the AM62x EVM may not be a good example to follow. We may need to pull someone that is familiar with the PMIC into this conversation if you want to use it for this function.

    Regards,
    Paul

  • 0 in reply to peaves
    Genius 3066 points

    Hi Paul,

    Thank you very much.

    I understand.

    Best regards,

    GR