New product: Breakout Board for microSD Card with 3.3V Regulator and Level Shifters

Posted by Brandon on 29 May 2015
Tags: new products

In September of last year, we started carrying our Breakout Board for microSD Card, which was the first board that I ever designed and routed here at Pololu. It is a simple breakout board that gives direct access to each contact available on a microSD card socket. However, since microSD cards operate at 3.3 V, it can be tricky interfacing them with a 5 V system. To address this, we made a new version with an integrated 3.3 V regulator and level shifters. Even with the extra components (and mounting holes, which the mechanical engineers at here Pololu are always pushing for), the board is still compact, measuring only 0.94″ × 0.9″, and it breaks out all of the contacts from a microSD card socket necessary to interface with the card through its SPI bus mode interface to a single 1×9 row of 0.1″-spaced pins. This allows easy use with breadboards, perfboards, or 0.1″ connectors.

You might recognize the circuit from our A-Star 32U4 Prime controllers, which use essentially the same level shifters to interface a microSD card with an Arduino-compatible ATmeg32U4 microcontroller running at 5 V.

For more information about this breakout board, see its product page.


Hi. Is this level shifting compatible with higher clock speeds? Can't tell from the photographs if its using integrated level shifters, or resistor networks.

High-speed buffer ICs are used for the level shifting, so the board should handle high-speed SPI signals without issue. You can see the level shifting circuit in the schematic of the SD breakout board at the bottom of its product page.


If I power it with 3v3 instead of 5v will it work with 3v3 logic MCU?
Hello, Adam.

It should work fine with 3.3V logic, but you might consider powering the board with a 3.3V source through the "3V3 (OUT)" pin and leaving the VDD pin disconnected to bypass the onboard regulator. Alternatively, you might consider using the simple breakout board for microSD cards since you do not need the additional level shifters.


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