I need to work on a design for an SD card connector. I'm having some trouble understanding the 'SD card detect' Switch and 'Write Protect' switch operation. Unfortunately, I don't have a physical model to confirm the working.

It's a Yamaichi FPS-00902960 SD card slot.

I've attached a picture of the switch circuit as given in the datasheet.

enter image description here

If card is inserted does 'card detect switch' connect to common terminal(ground)?

Would appreciate the help,



1 Answer 1


Yes. When the card is inserted, then the switch will be closed from detect to common. When the write protect is off, then that switch will be closed, and connected to common.

When the common is connected to ground and the switches are used with pull-up resistors it gives the cpu a digital signal for those two states.


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