SD Standard Overview

An Introduction to SD Standards

SD standards enable manufacturers to deliver high-performance products that enhance the experience of millions of people every day who listen to music, record videos, take photos, save data and use a mobile phone.

As the industry standard, the SD standard is utilized across multiple market segments of the portable storage industry, including mobile phones, digital cameras, MP3 players, personal computers, tablets, printers, car navigation systems, electronic books, and many other consumer electronic devices.

"Universal, portable and convenient SD standards lead the market today and will continue to evolve with the future of the digital world."

NAND technology showed amazing progress that provided exponential memory capacity increase. Much faster bus interface speed is required in accordance with increase of memory capacity to shorten access time to such capacity card.


UHS-II and UHS-III can provide much higher bus speed than UHS-I using Low Voltage Differential Signal (LVDS) on the 2nd row pins. The 1st row pins on UHS-II and UHS-III cards are used for the conventional normal speed, high speed and UHS-I bus interface signals to provide interoperability with those conventional interface host devices.

 

Form Factor SD microSD
Dimension SD Card SD Card
Card Capacity Type SD, SDHC, SDXC SD, SDHC, SDXC
Physical Number
of pins
9 pins(non UHS-II card)
+8 pins(UHS-II and UHS-III card)
8 pins(non UHS-II card)
+9 pins(UHS-II and UHS-III card)
Operating Voltage 2.7V - 3.6V(non UHS-II card)
VDD1:2.7v-3.6v/VDD2:1.70V-1.95V(UHS-II and UHS-III card)
Write-protect Switch YES NO

 

A new pin layout introduced to support the UHS-II bus interface also supporting UHS-III. The second-row pins on the full-size SD memory card and microSD memory card are used for the UHS-II and UHS-III bus interface signals. The first-row pins are used for the conventional normal speed, high speed and UHS-I bus interface signals to provide interoperability with those conventional interface host devices.

 

UHS-II and UHS-III Pin Layout

SD Standard Memory Cards

Simplified Specification Downloads

Simplified versions of selected SD memory card specifications are available for download by developers. To get access to the full specifications, simply join the SD Association.

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