SD Card Pull-up resistor selection

[prabhu.er]

pull up resistor

Dear All,

I have doubt about pull-up resistor selection in SD Memory Card Interface with System (Normally processor). In SD Card Product manual (Sandisk) they given pull-up resistor range is 10K - 100K. How I can identify exact the pull-up resistor value for my requirement.

Just I select the 50K ohm for CMD, D0-3. It is correct or otherwise I need to take any precaution when selecting pull-up resistor.

One more doubt also, the SD Memory Card have any internal pull-up resistor within that

 

[kender]

sd card pull up

Here's a data point. I have an SD card, which I use in SPI mode. My pull-ups are 10k. Power supply voltage +3.3V.

 

[wizpic]

sd card pull up resistor

This is what I used and it works great have a look from here

 

[bednyk]

sd card need resistor?

Were you using SD card with PIC microcontroller or AVR? Just wanna know what was the supply of uC, was it 3.3 or 5V?

Btw. have you got Fat system os SD or just a basic version of program.

BR,
Mike

 

[kender]

sd card interface pull-up

Were you using SD card with PIC microcontroller or AVR? Just wanna know what was the supply of uC, was it 3.3 or 5V?

Mike,

It was a PIC with +5V supply. 74VHC1GT12 buffers were used as level shifters for MOSI, SCLK and C#. 74LVC1G07 buffer was used for MISO. All buffers were powered with +3.3V.

- Nick

 

[doraemon]

sd card interface pullup

Hello!

Pullup value doesn't matter very much.
You can also use 1K, it will work. You can use 200K, 500K, and it still works
(I tried).
What you have to think about is consumption. If you design a low power
battery application, then it is better to put a high value in order to limit the
current at access time. If the value is too large (I don't know what is "too large",
I guess something over 1M), then you may have noise on the signal lines.
So the safe range is indeed 10 ~ 100 K. I use 51K in most of the applications
(usually in 3.3V) and the result is 60µA per signal line, while the processor
usually takes a few mA.

Dora.

Dear All,

I have doubt about pull-up resistor selection in SD Memory Card Interface with System (Normally processor). In SD Card Product manual (Sandisk) they given pull-up resistor range is 10K - 100K. How I can identify exact the pull-up resistor value for my requirement.

Just I select the 50K ohm for CMD, D0-3. It is correct or otherwise I need to take any precaution when selecting pull-up resistor.

One more doubt also, the SD Memory Card have any internal pull-up resistor within that