Shared between specified functions or applicationsstorage。If one or two applications occupy all the memory space, you cannot allocate memory space for other applications at this time.For example, calendars, SMS messages, and phone books (or contacts) may share dynamic memory in mobile devices.Common computer systemRandom access memory(RAM) separableDynamic random access memory(DRAM）And static random access memory（SRAM）The difference between the two is that DRAM needs to refresh the memory by the memory control circuit according to a certain period to maintain data storage, while SRAM data does not need to be refreshed, and data will not be lost during power on.
Chinese name
Dynamic memory
Foreign name
Dynamic Memory
Alias
DRAM
Properties
storage
Related products
DDR2
Use Scenarios
All types of computer systems, mobile devices such as mobile phones, data recording equipment, printers, control systems, etc
The working principle of dynamic RAM is the same as that of static RAM. Dynamic RAM is also composed of many basic storage elements in rows and columns.The basic memory circuit of 3-tube dynamic RAM is shown in Figure 1.In this circuit, the read select line and the write select line are separate, and the read select line and the write select line are also separate.
When writing
The write selection line is "1", so Q1 is on, and the data to be written is sent to Q2 through Q1gridAnd keep the information for a certain time through the grid capacitor.Let's take a look at the dynamic effects.
During read operation
First, read the data on the data line through the common precharge tube Q4distributed capacitance CD is charged. When the read select line is active at high level, Q3 is in a conductive state.If there is "1" in the original memory, Q2 is on, and the distributed capacitance CD of the read data line is discharged through Q3 and Q2. At this time, the information read is "0", which is just the opposite of the original memory information;If the original information is "0", then although Q3 has the conduction condition, Q2 is off, so the voltage on the CD remains unchanged, so the information read is "1".It can be seen that for such a storage circuit, the information read is exactly the opposite of the information originally stored, so it is necessary to reverse the phase and send it to the data bus through the readout amplifier.
Double data rate 2 memory（DDR2）Always in spherical grid array（BGA）Packaging mode supply.They have a low cycle time of 3 nanoseconds, or even 2.5 nanoseconds, so they can reach a data rate of 800 MHz.Conversely, compared with the original double data rate memory, they have a longer latency.However, double data rate 2 memory (DDR2) is significantly faster than double data rate 1 memory.In the case of 4/8 and 16 bit bus bandwidth, their storage capacity ranges from 256 megabits (Mbit) to 2 gigabits (Gbit).
The first generation double data rate memory adopts thin and small size package（TSOP）Or spherical grid array (BGA) packaging.Double data rate 1 memory (DDR1) provides a transmission rate of up to 400 MHz, with storage capacity ranging from 256 megabits to 1 gigabit.Double data rate 1 memory (DDR1) memory requires 2.5V voltage and 4,8,16 or 32 bit bus bandwidth.The biggest difference from double data rate 2 memory (DDR2): double data rate 1storage(DDR1) access and wait time is short.
Synchronous dynamic memory (SDRAM for short)clock frequencySynchronous operation with bus frequency.Their storage capacity ranges from 16 megabits to 512 megabits (16M – 512Mbit) and is available under the bus bandwidth of 4/8/16/32 bits.Typical operating voltage: 3.3 V.Package: BGA (spherical grid array) or TSOP (thin small size package).
Mobile Double Data Rate (Mobile DDR)storageIts storage capacity ranges from 64 megabits to 1 gigabit.Bus bandwidth: x16/x32 bits under 1.8V working voltage.Application field: all mobile devices, such as scanners,Personal digital assistant(PDA), mobile digital assistant (MDA), portable media player (PMP), mobile TV, digital camera, MP3 player
The running and standby current of the storage component is very low, but the capacity is very large,.Mobile SDRAM can be compared with traditional synchronous dynamic memory（SDRAM）Compatible, very suitable for mobile communication devices.Working voltage: 3.3V, 2.5V or even as low as double the moving voltageData rate(mobile DDR) The same 1.8V synchronous dynamic memory uses a space saving spherical grid array（BGA）Encapsulate with the contact area below.
Related products:
Amic:
Mobile SDRAM 16 Mbit – 128 Mbit, x16 bit, thin and small size package（TSOP）/BGA, 1.8V
Extended data output dynamic memory (EDO) and fast page mode dynamic memory (FPM) are not different in value, but it is not about technology.Their storage capacity also ranges from 1 megabit to 64 megabit, and the bus bandwidth is x4/x8/x16 bits (bit).We can provide 3.3V and 5V TSOP (thin small package) and SOJ (small packageJ-lead ）Encapsulation.Asynchronous dynamic memory no longerMass productionTherefore, the price is higher than other dynamic memories.
Related products
Amic, ESMT, ISSI:
Extended data output dynamic memory 4 megabits – 16 megabits, x16 bits (bit), small external lineJ-lead (SOJ)/Thin small size package（TSOP)， 3.3V。
Advantages and disadvantages
Announce
edit
It is verified that the dynamic memory is a storage technology with super large capacity, but its storage components require a refresh cycle controlled by the processor.Compared with other storage technologies such as static memory, it consumes relatively high power.Advantages: Compared with other types ofstorageIn comparison, the price per megabit is the lowest.
application area
Announce
edit
All types of computer systems, mobile devices such as mobile phones, data recording equipment, printers, control systems, etc.
