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SB_S
Beginner
620 Views

SD card and eMMC Transceivers for 1.8V

Do we need to have transceivers if we support  1.8V IO level on FPGA ? Doesn't have the capability to support the 1.8V ?

And also it requires the PU to 3.3V on these interface. ​Are these mandatory ?

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6 Replies
122 Views

Hi,

 

Is your question referring to SD/MMC and eMMC Card Interface Design?

If so, could you rephrase your questions again?

 

Thanks.

 

SB_S
Beginner
122 Views

​Yes , question is referred to  SD/MMC and eMMC Card Interface Design.

 

In the above table ,  for 1.8V SD/MMC Flash memory needs external transceiver . What does it mean ?

 

122 Views

I see, well since the HPS I/O use a fixed voltage level and cannot be changed dynamically, transceivers are required to support level-shifting and isolation for cards that can operate at 1.8 V.

 

The SD/MMC cards support various operating voltages, for example 1.8V and 3.0V. If you have a card which is at 1.8V and you eject it and replace it with another card, which is 3.0V, then voltage switching is required. Many SD cards have an option to signal at 1.8 or 3.0 V, however the initial power-up voltage requirement is 3.0V. To support these different voltage requirements, external transceivers are needed.

 

More information here on page 1721 (Flow Diagram).

 

Regards.

SB_S
Beginner
122 Views

​So for eMMC this trancievers  are not required right ? because this voltage doesn't change as SD card . So 1.8V emmc device should work .

122 Views

Hi,

 

If the operating voltages are both 1.8V as mentioned, external transceiver are not required.

 

Regards.

SB_S
Beginner
122 Views

​Thanks