Everything You Need To Know About DRAM IC

DRAM IC image source Freepik

Dynamic random-access memory, which is also known as Dynamic-RAM, or DRAM is a type of  RAM semiconductor memory.

DRAM  is made of capacitors and transistors that are designed to store each bit of data in the memory cell. Keep in mind that when used for data storage applications, both the transistor and capacitors tend to rely on the metal-oxide-semiconductor (MOS) technology.

DRAM is widely used in the modern digital technology. In case you are building an electronic device that is expected to have an impact in the data-driven world, then it is important to have adequate information about DRAM.

In this article, we will discuss all that you should know about DRA ICs. You will also learn about things you should look out for when buying DRAM ICs.

How DRAM works-complete guide

To understand how DRAM IC works, you should first know that data in computers is stored in binary form. It can be either 0 or 1.

These two forms represent the states of electric circuits. This is where the importance of integrated circuits come in.

Transistors preserve or record the states of the circuits that are responsible for data storage. These two important electronic components work together to achieve this goal of data storage and management.

One of the key functions of a transistor is to serve as a switch.

 Transistors in DRAM are designed to change the state of the capacitors. They utilize their fast-switching property to do so.

Capacitors in electric circuits tend to lose their charges over extended periods. To mitigate this, the charges that are used for the data storage must be refreshed continuously. Probably after every few milliseconds.

Transistors, again, play an important role in refreshing the charging rate, a key element in the overall operation of the transistors.

Operation of DRAM

 At the heart of a dynamic RAM is the MOS technology. It is responsible for the operation of the DRAM. The memory cells of the DRAM store every bit of the data and also facilitate the movement of data. On the other hand, the MOS technology serves as a switching device in the whole setup.

The level of charge in the capacitor will determine the state of the DRAM. The charge can either be high or low, denoted by “1” or “0” respectively.

 Thousands of memory cells are combined to form a complete DRAM IC setup. These cells also make up the memory capacity of the RAM.

 The memory cells are arranged and organized in a rectangular configuration.  These cells are split to form sub-arrays within the IC chip.

The arrangement and organization of the cells help to reduce the time that is taken to access the individual cells within the system.

Read/write operations in DRAM

Read and write are among the important operations that are executed by DRAM.

The presence of a capacitor is to minimize the possibility of noise due to the changes in states.

 Several lines are used for the execution of the read and write operations in dynamic RAM.

· Colum Address Strobe:  The main function of this line is to select the exact column that is to be addressed during the read and write operations. The line makes it possible for any particular column to be addressed.

· Output enable:  This line is used for controlling multiple memory chips that are parallel to each other. It determines the output that is fed to the data pins. In most DRAM applications, OE is permanently low.

· Row Address Strobe (RAS): This line points out the exact to that is to be addressed. The designated address inputs are captured on the falling edges of the RAS line.

· Write Enable: This signal line of a dynamic RAM determines whether any falling edge is a read or write signal. The low state will trigger the write action while the high state will trigger the read action.

Refresh operation of DRAM

Still, on the DRAM working mechanism, let’s look at the refresh operation of the dynamic RAM.

A major limitation that hinders DRAMs from delivering optimum performance is current leakage by the capacitors.

 In other words, the capacitors don’t hold their charges forever.

Leakage of current translates to the loss of memory or data.

 The good news is DRAMs are designed to mitigate such losses. The most effective method is to refresh data periodically.

Data in the DRAM is reinstated to its initial form. In doing so, it is not lost from the memory module.

 The refresh mechanism of the DRAM is enabled during the manufacturing process.

 Usually, most DRAM manufacturers specify that each row of memory cells should be refreshed after every 64 milliseconds.

This time interval falls within the JDEC standards for the DRAM refresh periods.

 There are various ways in which the refresh process in DRAM is achieved.

 In most DRAM chips, all the rows are refreshed together after 64ms. In other processors, each row is refreshed one at a time.

Some DRAM  ICs are designed in a way that a section of the memory system is refreshed at a time. This means that several rows are refreshed first before another row is refreshed. This mechanism is usually used in high-performance applications where speed is of the essence.

Regardless of the technique used for refreshing DRAM, a counter must be used to track the next row of memory cells that are supposed to be refreshed. This explains why most DRAM ICs are embedded with counters to do this job.

DRAM IC size

Size is one of the most important features of DRAM IC. It is one of the things that you should look out for when buying dynamic RAM ICs.

Usually, as the memory size of a device increases, it tends to affect various areas of its performance. This is because it causes a strain on the data capacity of the DRAM

One of the impacts is on the data integrity of the device.

The size can affect the signal-to-noise ratio on the DRAM. This will eventually compromise the quality of the data.

It can lead to cases of data corruption.

The ratio of signal to noise will always depend on the capacitance of the DRAM IC.  How much charge can the capacitor hold?

An increase in the capacitance of the DRAM IC will cause a reduction in the signal-to-noise ratio. This in turn guarantees the quality and integrity of data that is stored in DRAM.

For this reason, it is important to choose DRAM chips that have high capacitance.

Even as we focus on the size, we have to keep in mind that other factors affect the quality and integrity of the data that is stored in these memory chips.

Chip design is just one of these factors. It specifies the arrangement and configuration of memory cells on the DRAM IC.

Error detection and correction in DRAM IC

Given the operational environment of DRAM ICs, it is a fact that electrical and magnetic interferences are a constant factor.

Any form of interference can compromise the performance and integrity of these DRAM ICs, especially when we consider that data is in the form of electric charges.

Electric and magnetic forces can easily flip the state of charges from low to high and vice-versa.

Since these changes in memory states are unintentional, data integrity will be compromised.

 The background is blamed for the majority of the errors on the DRAM chips. Neurons from external sources can change the contents of the DRAM cells.

Different techniques have been designed to mitigate such interference. One method entails the use of redundant memory bits on the memory cells.

Types  of DRAM ICs

Dynamic RAM chips come in different types and configurations.  Each type is designed to be used in its respective application area.

Common types of DRAM ICs include the following:

· SDRAM (Synchronous DRAM) IC: It derives its name from the fact that it is synchronized with the existing system bus. It relies on the clock signals to control the data transfer process.

· DDR SRAM (Double Data Rate Synchronous DRAM: This type of DRAM is designed to double the data transfer rate. It does so by transferring data both on the rising and falling edges of the clock signal.

· LPDDR SDRAM (Low Power Double Data Rate SDRAM): This is a low-power option of  SDRAM. It is mostly used on small and compact devices such as mobile devices. The DRAM is optimized for performance and efficiency.

· DDR5 SDRAM: This is the latest generation of DRAM that is used on most modern computers. It is mainly known for delivering exceptional performance. 

Benefits of DRAM

Some of the top benefits of using DRAM IC include:

·  Fast read and write capability

· Cost-effective, is cheaper than SRAM

· Power-efficient as does not rely on constant power to retain data.

· Compact design means that it makes proper use of the existing space. This makes it ideal even for small devices. 

FAQs about DRAM IC

What is the difference between DRAM and SRAM?

Both Dynamic RAM and Static RAM are memory types that are found in computers.  The main difference between the two is in terms of their refresh rate. Data in the DRAM is stored in a capacitor-transistor pair, which is originally designed to have refresh pulses after every few seconds. This is mainly because of the capacitor leakage.

On the other hand, SRAM relies on transistors only to store data. This means that refresh pulses are not required here.

The difference is also in terms of their speed. SRAM is faster than DRAM. This, conventionally makes SRAM more expensive than DRAM.

How long can DRAM IC last?

The lifespan of DRAM chips is measured in hours and is calibrated in terms of Mean Time Between Failures (MTBF).

A year has approximately 8500 hours.

 Most DRAM chips are rated to have 50,000 hours MTBF.

However, the lifespan will depend on other factors, among them the application area. If you are using a device that runs constantly, then the lifespan will be short.

Of course, the quality of the DRAM IC will also matter. Ensure that you buy premium-grade DRAM chips from reputable brands if you want them to serve for long periods.

How does DRAM IC retain data?

Data storage in DRAM IC is executed by the presence and absence of electric charge.  

Electric charges are translated as data. The presence of charges is an indication of data availability. Over time, the charges tend to leak from the capacitor and we can translate this to memory loss from the DRAM chip. If the DRAM is not refreshed constantly, the memory will be lost permanently.

Can data be stored permanently in a DRAM cell?

No, DRAM retains data only as long as the device remains in an ON state. Once the device is powered off, the memory will be lost.

Additionally, DRAM needs to be refreshed constantly to retain its memory for an extended period. This is done to prevent leakage of charges.

Conclusion

After having all the important information about DRAM ICs, the next step is making the right purchase of this product.

Now you appreciate the roles that these chips play in modern electronics and how you can use them in your products.

The most important step you should take when buying DRAM  ICs is knowing the key features and specifications of the chip.

From there, you can start looking for where to buy the chips.

 Choosing a reputable DRAM IC supplier in China has always proven to be the best move. It will ensure that you get a high-quality IC chip for your product.

Rantle East Electronic is one such distributor. We are a global DRAM IC distributor that is always committed to meeting the needs of our clients.

Regardless of the type and specifications of DRAM ICs that you are looking for, be sure to find them in our store.

With over 20 years of experience in the industry, we are one of the leading electronic component distributors in China. All you need is to contact us and we will be glad to deliver.