Need a Buffer IC which work with SDIO Mode SD card.

Koustubh Joshi

Prodigy 240 points

Other Parts Discussed in Thread: SN74HCS245-Q1, SN74LVC2G34, SN74HCS126, SN74HCS125

Hello,

I am looking for an Buffer/Mux IC for one of my design in between the MCU and SD card.

The Communication interface we use here is SDIO so i want the SDIO supported buffer IC which works with SD card.

Thank You.

over 4 years ago

0 Emrys Maier over 4 years ago

TI__Guru* 97266 points

Hello,

There are multiple versions of the SD protocol. What kind of solution you use will depend on the directionality of signals and number of lines used, in addition to the usual supply voltage and data rate concerns.

Can you give us more details on your application?

0 Koustubh Joshi over 4 years ago in reply to Emrys Maier

Prodigy 240 points

Hello Emrys,

Thanks for replay. I am using 4bit SDIO Mode.(Data0 to Data3, CMD, Clk). SDIO CLK up to 48MHz

Supply voltage is 3.3V.

0 Emrys Maier over 4 years ago in reply to Koustubh Joshi

TI__Guru* 97266 points

In that case, we don't have any buffer that can support the application.

The data lines (D0 to D3) are bi-directional, and thus a buffer cannot predict the direction and redrive the signals. Any "auto-bidirectional" buffer (like the TXB0108E) will have reduced drive strength to allow for switching directions, which negates the purpose of adding a buffer.

If you can find some way to determine when each line is transmitting or receiving, a transceiver like SN74HCS245-Q1 could be used.

For the clock and cmd lines, you could use a buffer like SN74LVC2G34.

0 Koustubh Joshi over 4 years ago in reply to Emrys Maier

Prodigy 240 points

Thanks for your replay. Actually i want the buffer like IC which can give me the output BUS control i.e Tri-state Mode and Normal mode in which MCU access the SD card for read write operations.

0 Emrys Maier over 4 years ago in reply to Koustubh Joshi

TI__Guru* 97266 points

There are many 3-state buffers available. You could build your own transceiver from separate devices instead of using the '245 function for finer control. For example, an SN74HCS125 + SN74HCS126 would work for having 4 independent bidirectional channels (the OE and OE\ signals can come from the same source for a direction control signal).

This table is already sorted for 3-state output buffer devices:

https://www.ti.com/logic-voltage-translation/buffers-drivers-transceivers/noninverting/products.html#p116=3-State

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Need a Buffer IC which work with SDIO Mode SD card.