TXB0108: Using the TXB0108 in an SD card design

Dante Fasano

Part Number: TXB0108
Other Parts Discussed in Thread: TXS0108E, TXS0206

I have a design for an interface to a SD card bus using a TXB0108. I'd like someone to review it and tell me if there is anything incorrect.

The circuits of interest are in the lower left corner.

Thank you

Dan

over 2 years ago

0 Jack Guan over 2 years ago

TI__Mastermind 41076 points

Hey Dan,

I would recommend the TXS0108E/TXS0206 instead of the TXB0108 for SD interfaces. The TXS family devices differ from TXB as the device has internal pull up resistors that are suitable for I2C/open drain applications. Ensure that the PCB traces/loading conditions to a minimum to meet the required data rate of your application (section 11-12 of the datasheet).

Also see page 6 of this reference doc for more information in regards to SD interfaces.

Regards,

Jack

0 Dante Fasano over 2 years ago in reply to Jack Guan

Intellectual 300 points

Hi Jack,

Thanks for the response. Can you say why you recommend the TXS type of part? TI was recommending the TXB.

Also, in this design, it is a SD card. So, the clock must be an input to the design. That is why a part like the TXS0108E might be

ok because it does not have a dedicated clock pin.

0 Jack Guan over 2 years ago in reply to Dante Fasano

TI__Mastermind 41076 points

Hey Dante,

The TXS device is recommended for SD cards because SD card interfaces are initially open drain mode- which the TXB family cannot support.

Regards,

Jack

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TXB0108: Using the TXB0108 in an SD card design