Power off Teensy 3.6 SD card?

[akh]

I'm working on a very low power datalogging application using a Teensy 3.6 that writes to a microSD card. To reduce power consumption I want to place a high-side switch (P-channel MOSFET) on the card's Vdd line and power off the card when it's not in use. From the Teensy 3.5/3.6 schematic it appears that the microSD socket's Vdd is tied to the 3.3V rail. My question is this: Is there a way to modify the Teensy 3.6 board so that the microSD Vdd line can be switched on and off?

-Alex

Update: The µSD socket appears to be a Hirose DM3D-SF that has all solder connections exposed. I could desolder the Vdd pin, solder a wire to it, and insulate underneath. This could be prone to damage whilst inserting or removing the card though. Are there any other options available?

 

[CaptainHooyah]

Hi, what did you end up doing?

I would like to use the built-in SD card but it really increases the power consumption.

When I use the snooze library I can Hibernate a 3.6 at 60 uA, but if a card is inserted is hibernates at about 500 uA. I would like to avoid using an external uSD card if possible.

 

[tni]

Get a better SD card. E.g., I have a Transcend 16GB card that uses 85uA sleep current. You have to make sure the card is initialized before hibernating, otherwise it will draw a lot more power.

If you want to switch off SD power, you need to keep in mind that some cards have a huge amount of leakage current through the IO pins when powered off. So you would have to make sure that none of them are high and that pull-ups are disconnected.