How to distinguish SDRAM(SDR)/DDR1/DDR2/DDR3

2021-01-07 11:04:57 fandoukeji

How to distinguish SDRAM(SDR)/DDR1/DDR2/DDR3

Power supply voltage distinction: SDR-3.3V, DDR-2.5V, DDR2-1.8V, DDR3-1.5V

The voltage is not a reliable way to judge, because the low-power LPDDR voltage is 1.8V and the same as the DDR2 voltage, and the low-power LPDDR2 voltage is the same as the DDR3 voltage, so it is easier to confuse.

Different memory types can be reliably distinguished by the difference of memory particle signal lines:

1) No DQS must be SDR

2) With DQS without ODT, it must be DDR1

3) With DQS, ODT without Reset signal, it must be DDR2

4) At present, there is a Reset signal, it must be DDR3 memory, and DDR3 also has an extra ZQ pin (240 resistance to ground).

5) These types of memory all work in a synchronous state, that is, they have Clock input, and they all belong to the SDRAM (random dynamic memory) type. Some storage devices have DQ pins and no Clock. Generally, storage devices such as SRAM and Flash work in an asynchronous state and generally have low speeds.