I am trying to develop a microSD card module myself. My microSD card module is working at 3.3V and my microcontroller is operating at 1.8V. I have therefore used TXB0104 voltage level shifter to interface.

Attached below is my PCB schematic. The legend is as below: BOOST_OUT= 3.3V BUCK_OUT= 1.8V

I am not quite sure if my circuit is entirely correct. Some specific doubts that I have are:

  1. I am using microSD card in SPI mode. Are my socket pin interpretations correct? I have used Sandisk datasheet as my reference (Page 10 of https://www.alliedelec.com/m/d/04db416b291011446889dbd6129e2644.pdf)

  2. Should I pull up all my DAT0:3 pins to BOOST_OUT (3.3V)? I know that the microSD card datasheet says that this is applicable for SD Mode, but am confused if this is applicable to SPI also.

  3. Should I pull up Chip Select (CS) to Boost_Out. In doing so, what will happen? I want to control the ON and OFF of the SD Card module in my application. I therefore have pulled my OE pin of TXB0104 to micro controller. Do I have to do the same for CS also or is only one of them necessary?enter image description here

Too many doubts, sorry for blasting them! I will be grateful for your help and support :)

  • \$\begingroup\$ Why not run your SD card at 1.8V? You get access to faster speeds then with CMD6. \$\endgroup\$ – Majenko Jun 26 at 10:23
  • \$\begingroup\$ SD Cards or microSD cards dont usually run at 1.8V as per the specs and multiple forums. They run at voltages between 2.7V to 3.6V only. I had to therefore design a voltage level shifter. \$\endgroup\$ – Anmol Jun 27 at 5:47
  • \$\begingroup\$ Please tell me if I am missing something here! \$\endgroup\$ – Anmol Jun 27 at 5:47

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