SRAM IC Distributor in China
- Features an 8-pin low power, high performance device.
- Fast data access but holds less data per unit volume.
- Supports unlimited instantaneous writes to the memory array.
- Available in 512 Kbits and 1 Mbit densities and 64 Kbit up to 1Mbit.
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Reliable SRAM IC Supplier - Rantle East Electronic
RANTLE SRAM IC is a standalone volatile memory that offers designers an easy and inexpensive way to add more RAM to their application. RANTLE SRAM IC features an 8-pin low power, high performance device has unlimited endurance and zero write times, making them ideal for applications involving continuous data transfer, buffering, data logging, audio, video, internet, graphics, and other math and data-intensive function.
RANTLE SRAM IC contains 6 transistors (four transistors configured as two-cross coupled inverters and additional two transistors to control the access to the memory cell. This provides fast data access but holds less data per unit volume. RANTLE SRAM IC offers non-volatile RAM storage and is ideal for applications that need to write very often to the memory. This device is significantly lower cost than other non-volatile RAM devices and the data is backed using an external battery.
RANTLE SRAM IC also allow designers to use a smaller microcontroller rather than moving to a larger device just to get more on-board RAM. RANTLE SRAM IC is used in cached memory and video card memory. It features low-power CMOS technology, standard 4-pin SPI interface, unlimited writes to memory, battery backup, 32- byte page, high speed SDI and SQI, industrial temperature range and small, 8-lead SOIC, TSSOP, and PDIP packages.
RANTLE SRAM IC supports unlimited instantaneous writes to the memory array. RANTLE SRAM ICs are available in 512 Kbits and 1 Mbit densities and 64 Kbit up to 1Mbit.
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SRAM IC: The Ultimate FAQ Guide
In case you have questions about SRAM IC, your answers are all here.
Whether you have questions about the working principle, features, uses, components or how to read data in SRAM IC, the answers are all here.
Basically, this guide will make you an expert in SRAM ICs.
Take a look:
- What is SRAM IC?
- Is an SRAM IC Non-Volatile?
- What are the types of SRAM IC?
- What is SRAM IC used for?
- What is the difference between SRAM IC and DRAM IC?
- Does SRAM IC require Refreshing?
- What is an SRAM IC Cell composed of?
- How does an SRAM IC Work?
- What is Synchronous and Asynchronous SRAM IC?
- What are the Benefits of using SRAM IC?
- What are the Limitations of the SRAM IC?
- How do you Read an SRAM IC?
- How is an SRAM IC Written?
- Why is SRAM IC Expensive?
- What are the Specifications of an SRAM IC?
- What is the Speed of an SRAM IC?
- How is SRAM ICs Packaged?
- What is Static Noise Margin in SRAM IC?
- What Features are Provided for an SRAM IC?
- Are there Quality Standards for SRAM IC?
- How much does SRAM IC Cost?
- How do you Test SRAM?
- Which Material is SRAM IC made of?
What is SRAM IC?
SRAM refers to Static Random Access Memory.
An SRAM IC is a memory chip capable of holding onto its memory data with a continuous supply of power.
This way, it does not need to be refreshed like in a DRAM IC.
An SRAM IC is desired for its faster access and cycle times and low power usage, over the DRAM IC.
It is, however, costlier than a DRAM chip as it costs more to produce.
Is an SRAM IC Non-Volatile?
A non-volatile memory type preserves its stored information when the power supply is interrupted. A typical SRAM IC’s memory type is volatile.
This means that without power, and SRAM IC will lose the data it has stored in its cells.
However, an SRAM chip can be made non-volatile by introducing a chargeable battery to provide a continuous supply of power.
This novel chip is referred to as a Non-Volatile SRAM (nvSRAM) IC.
Here, power interruption to the SRAM IC is preceded by a supply from the packed battery.
The continuous supply of power ensures stored data is preserved by the chip.
What are the types of SRAM IC?
You will find various classifications of the SRAM IC. These groupings come about as a result of the different basis of classification.
Classification could be based on the following parameters.
- The type of transistors used.
- How the SRAM chip functions.
- The salient features of the SRAM chip.
- By the flip-flop cell configuration.
Generally, though, the SRAM IC is classified according to its functionality.
This way, you find the SRAM categorized into the asynchronous and synchronous SRAM IC.
The asynchronous and synchronous SRAM ICs are further divided based on their applications.
For asynchronous SRAM ICs, you will find such SRAM chips designed for low speed, medium speed and high-speed applications.
For the synchronous SRAM IC, you will find the following design distinct types.
- The Flow-through SRAM IC
- The Pipelined SRAM IC
- The Interleaved SRAM IC
- The Linear Burst SRAM IC
- The Late Write SRAM IC
- The Zero Bus Turnaround (ZBT) SRAM IC
- The Double Data Rate (DDR) SRAM IC
You will appreciate a special mention of the non-volatile SRAM (nvSRAM) IC.
This is basically an SRAM chip combined with a battery capable of storing charge. The battery ensures continuity in the power supply.
This way memory is made non-volatile.
This SRAM works effectively over time, with one major drawback.
As batteries always do, the nvSRAM IC battery will lose its charge after a while.
As a result, there will be no continuous supply of power to the chip leading to a loss of data.
What is SRAM IC used for?
You find that the static RAM IC is intended to complement the DRAM IC in the following ways.
It is used to replace the DRAM IC in applications needing quick execution by the processor.
Additionally, it is also used as an alternative for the DRAM IC in situations that need low power usage.
Some applications for the SRAM IC falling under these parameters include:
- An SRAM IC is employed as a cache memory for computers.
- High speed registers also employ SRAM ICs in their architecture.
- On video cards, SRAM ICs are used as part of the RAM digital-to-analog converter.
- Modern appliances and automotive electronics utilize SRAM ICs for memory storage.
What is the difference between SRAM IC and DRAM IC?
You find that both the dynamic and static RAM ICs have volatile memory.
However, there are a number of differences between a dynamic (DRAM) and static (SRAM) RAM IC.
- An SRAM IC is able to hold on to its memory data without the interruption of the power supply. However, a DRAM IC needs to be constantly refreshed in order to retain its memory data.
- SRAM ICs are utilized as cache memory in computers. DRAM ICs are utilized mostly as main computer memory.
- To store a single bit of memory, an SRAM IC requires six transistors. A DRAM IC requires one transistor and capacitor combination.
This leads to a high cost per bit for an SRAM IC.
- The DRAM IC has a larger density allowing it to have larger storage capacities than the SRAM IC.
This is due to their smaller cell structure compared to an SRAM chip.
- The structural composition of an SRAM chip lacks the presence of capacitors utilizing only transistors.
A DRAM IC’s memory cell architecture consists of a transistor and a capacitor.
- SRAM ICs are on-chip memories and characterized by short access time. DRAM ICs being off-chip memory chips are characterized by longer access time.
- Charge leakage in the DRAM IC capacitors causes it to have more power consumption needs than SRAM ICs.
- In cost comparison, SRAM ICs are costlier than DRAM ICs. This is due to the high cost per bit attached to an SRAM IC.
Does SRAM IC require Refreshing?
No, it does not.
A DRAM IC needs to be refreshed periodically to preserve the data stored in the memory cells. This is because a DRAM ICs memory cell’s transistor is prone to leakage, causing the discharge of the capacitor.
Data is lost with the discharging of a capacitor. To prevent loss of this information, a DRAM IC needs to restore the data in a refresh process.
This process is fast and continuous, taking a fraction of a second. Refreshing occurs when a new electronic charge is transmitted to the capacitor.
Contrarily, this refresh process is absent in an SRAM IC.
This is because an SRAM IC‘s memory matrix lacks a capacitor consisting of typically six transistors.
The absence of a capacitor means there is no discharge and thus no need for a refresh process.
What is an SRAM IC Cell composed of?
Layout SRAM Cell
You will find three different types of SRAM IC cells.
The differentiation is brought about by the load type employed by the cross-coupled inverters.
Thus we have the 4T cell, the 6T cell and the TFT cell.
· The 4T Cell
The 4T cell type consists of four n-type metal-oxide-semiconductor transistors and a pair of poly load resistors.
Two of the NMOS transistors are connected to the word line via their gates, creating a link with the columns.
They are referred to as the pass transistors.
The poly-load resistors create the cross-coupled inverters.
The other NMOS pair of transistors controls these cross-coupled inverters.
The 4T cell is smaller than a 6T cell.
This is because, in its design, the 4T cell packs the poly-load resistors over the transistors. However, it is larger than a DRAM IC’s cell four times over.
Additionally, you find that SRAM ICs with 4T cells lack the high-speed performance of DRAM ICs with the 6T cell.
Besides, the chip has high resistance as every cell has current flowing through a resistor.
This increases the chip’s sensitivity to static noise and soft error.
· The 6T Cell
The 6T cell is composed of six transistors.
Four transistors are n-type MOS while the other two transistors are p-type MOS transistors.
Rather than use poly-load resistors for load, the 6T cell employs a p-type MOS transistor.
A pair of NMOS transistors is linked to the bit line.
An SRAM IC with a 6T cell structure offers better performance speeds than that with a 4T cell design.
Moreover, it has a lower sensitivity to static noise and power consumption due to its superior electrical performance.
This cell structure has one major drawback. Packing six transistors into one cell causes it to be overly large.
Since a single bit is stored in a single cell, this causes the cost per bit to be high.
· Thin Film Transistor (TFT) Cell
This cell design incorporates four n-type metal-oxide-semiconductor transistors, and a load pair referred to as TFTs.
The TFTs are p-type MOS.
This cell design is intended to suppress the limitation of high electrical resistance in a 4T cell.
Also, the thin-film transistors are made of polysilicon strata coated over a silicon surface, with source and drain.
The gate to a single thin film transistor is connected to the reverse inverter’s gate.
There is a thin insulating oxide layer between the gates.
You find that TFT technology is sophisticated and has not caught up with the market.
Besides, its electrical performance is inferior to the 6T cell.
How does an SRAM IC Work?
You find that the SRAM IC with a 6T cell structure is most favored.
Thus, its working methodology is described as follows.
To program an SRAM IC cell, the memory location of the data value to be stored is selected. The cross-coupled latches store the data bit.
With the chip memory organized in rows and columns an SRAM IC can diffuse a whole row.
The access transistors are enabled by the column line which allows cell access in the SRAM IC. The row lines provide a highway for data movement when an SRAM IC is to be read or programmed.
What is Synchronous and Asynchronous SRAM IC?
The asynchronous and synchronous SRAM ICs are the two types of memory chip you can find based on operational methodology.
SRAM Memory Interface
· Asynchronous SRAM IC
With an asynchronous SRAM IC, you find three control signals that direct processes.
These clock signals are generated by the asynchronous SRAM IC in response to changes at the host device’s address pins.
The three control signals are the Chip Select (CS), the Read Enable (RE) and the Write Enable (WE).
The Chip Select (CS) basically carries out chip selection before a read/write.
The Read Enable (RE) controls the reading process, whereas the Write Enable (WE) directs the writing process.
De-selection of a chip refers to an inactive mode where the device consumes little to no current. It also keeps the address pins at high impedance.
Compared to the synchronous SRAM chip, the asynchronous SRAM IC has a lower performance rating.
· Synchronous SRAM IC
With the synchronous SRAM IC, an external clock is utilized to time the read and write cycles of the chip.
Many times, this external clock is the processor clock.
By using the processor clock, the access and cycle times are greatly reduced improving operation speeds.
What are the Benefits of using SRAM IC?
You find the following benefits of an SRAM IC:
- Unlike DRAM ICs, SRAM ICs do not require to be refreshed in order to hold onto memory data.
- With regard to speed, SRAM ICs provide better performance than DRAM ICs.
- SRAM ICs are implemented in the creation of caches that are sensitive to speed.
- The power needs of an SRAM IC are lower than that of a DRAM IC.
- An SRAM IC has long write endurance.
- SRAM chips have large densities.
What are the Limitations of the SRAM IC?
An SRAM IC exhibits the following shortcomings.
- SRAM ICs are costlier in comparison to DRAM ICs.
- When power is cut, data is lost in an SRAM IC.
- SRAM ICs are unable to refresh programs.
- SRAM ICs have a low capacity for storage.
- The design for an SRAM IC is complex.
How do you Read an SRAM IC?
You find that the memory cells in an SRAM IC are organized in rows and columns. The rows are referred to as word lines with the rows as bit lines. Every memory cell, therefore, has a distinctive location that is identified by a row and column.
You can carry out a read process on an SRAM IC as follows.
A cell is selected when the pair of access transistors are on.
The access transistors are connected to the word line.
Besides, this ensures the cross-coupled inverters are connected to the SRAM IC chips electrical connection.
The supply voltage is administered to the selected row.
Thereafter, the cross-coupled inverters are connected to the bit lines.
There is a sense amplifier that is connected to the bit lines.
The sense amplifier identifies the binary logic value stored in a cell by virtue of its charge.
It then transmits this value to the buffer for output.
The buffer is linked to the output pin, which is equal in number to the sense amplifiers, where it is read.
How is an SRAM IC Written?
You find the writing procedure begins with the selection of the address of the memory cell in which the data is to be stored.
This is done by providing the row and column address. The data to be stored is fed at the input pad.
The Chip Select and the input signal are all set to low.
This allows for the feeding of the data to be stored at the input pad.
As the clock transitions to high, the location and data write are latched to initiate the write-process.
This way, the data is transferred for storage in the designated cell.
Why is SRAM IC Expensive?
You find an SRAM IC is expensive due to its high production cost.
An SRAM IC cell is a sextuplet array of MOS transistors. A DRAM IC is a dual composition of a transistor and capacitor.
This memory structure composition attributes to its high production cost and eventually high market price.
Additionally, an SRAM IC has superior qualities in a manner of speed and power consumption.
What are the Specifications of an SRAM IC?
You find the following specifications attached to an SRAM IC.
- The SRAM chip’s access time, which is provided in nanoseconds.
- The data transfer rate for the SRAM IC. This is measured in megahertz (MHz)
- The SRAM IC’s capacity.
- The operating voltage in volts for the SRAM IC.
- The SRAM IC’s memory density given in kilobits.
- The package in which the chip is housed.
- The number of pins on the package.
What is the Speed of an SRAM IC?
You find the SRAM IC has a speed advantage over the dynamic RAM chip.
Presently, you will find SRAM ICs operating at very high processor speeds.
This is besides having impressively fast access time and cycle time that could reach as low as ten nanoseconds.
How is SRAM ICs Packaged?
There a variety of package types that you will find for an SRAM IC.
The package type depends on the application and type of the SRAM chip.
Besides, you will find the packages with different pin counts to fit certain defined design elements.
Some package types employed include.
The fine pitch ball grid array package is typically a ball grid array.
The difference between the fine BGA and the regular BGA is the number and size of solder balls.
The small outline integrated circuit package is a small package that mimics the DIP package in design. It is mounted on the surface of the circuit board.
The thin small outline package has very little space between its leads and a reduced profile.
This allows them to occupy less space. They are also surface mounted.
The ball grid array utilizes solder balls for electrical connection. It provides a higher number of connection points this way.
A dual flat no-leads package lacks leads. It is four-sided and mounted on the circuit board surface.
The shrink small outline package corresponds to the small outline integrated circuit package, only smaller.
What is Static Noise Margin in SRAM IC?
The Static Noise Margin of an SRAM IC is obtained from the voltage transfer curve graph of a chip’s paired inverters.
You internally square the two voltage transfer curves and select the largest square.
You then identify the length of the square along the x-axis to provide the Static Noise Margin in volts.
A DC noise can change an SRAM IC’s state of the memory cell when it exceeds the Static Noise Margin.
This change of state usually results in a loss of data.
You find that the supply voltage and the cell and pull-up ratio affect an SRAM chip’s Static Noise Margin.
The driver and load transistors’ size while in the read-process provide the cell ratio.
The pull up ratio is provided by the load and access transistors during a write process.
You will find different values for the Static Noise Margin depending on the cell state.
An SRAM IC with no operation will have an SNM value different from that during a read process.
A read process will have an SNM value different from that of a write process.
Basic SRAM Architecture
What Features are Provided for an SRAM IC?
When identifying SRAM IC chips, you find the following features useful.
- An option of differing densities for every SRAM chip.
- An option for the Real-Time Clock (RTC).
- Options for the serial interface.
- A variety of configuration for the chip’s bus-width.
- High assigned reliability.
- Capability to perform unlimited write cycles.
- Temperature grading that is suitable for both industrial and automotive applications.
Are there Quality Standards for SRAM IC?
There are a variety of standards that you would find for the SRAM IC.
The standards are in reference to the different applications, composition and feature aspects. Some notable standards include the following.
- MIL-M-38510/613: A standard for a CMOS SRAM IC whose mode is selectable.
- DESC-DWG-5962-88611: This standard includes a CMOS SRAM IC with Separate Input and Output.
- DESC-DWG-5962-89598: A standard for a CMOS 128K x 8, low powered SRAM IC.
- DESC-DWG-5962-08215: A standard for radiation-hardened 512K x 8-Bit SRAM IC of low voltage.
- DESC-DWG-5962-06261: This standard is specific to SRAM chips with 512K x 32 bits (16MB) and used in embedded systems.
- DESC-DWG-5962-01532: A standard for radiation-hardened monolithic silicon chip with low voltage. This while being a multichip module.
- DESC-DWG-5962-86875: A standard for a Dual Port CMOS SRAM IC.
How much does SRAM IC Cost?
The SRAM IC is costlier than the DRAM IC.
This is due to the high cost of producing a single SRAM chip whose cell structure consists of six transistors.
Remember, this is in comparison to a DRAM IC cell which is composed of a single capacitor and transistor.
Also, this difference in cell structure is important because, for both chips, a single bit of data is stored in a cell.
As such, you find the SRAM IC chip incurs more costs during manufacture to store a single bit of data.
You will find a gigabyte of an SRAM IC used as cache going for thousands of dollars.
A DRAM IC of similar capacity goes for an average price of fifty dollars. This gets cheaper at lower capacities.
How do you Test SRAM?
You find that there are several ways to test an SRAM IC.
However, each test seeks to establish the reliability of a particular aspect of the SRAM IC. Some tests are described below.
· Data Bus Integrity Test
This test seeks to determine whether all the data lines on the data bus are properly connected. To test for the integrity of the data bus, you write a “0” value to a particular memory location. You then read the value back, ensuring it is still a “0” value.
Thereafter, you repeat the process this time using a “1” value. With this test, you can tell if there is a disconnection of your lines.
· Walk-through test for “1s” and “0s”
It could be that the problem is not a disconnection of wires as sought in the data bus integrity test.
Probably several wires could be bridged together, or to the supply voltage pin or the ground wire.
The walk-through test seeks to establish the truthfulness of a single bit of data in a data line. Therefore, for an 8-bit data bus, you will carry out data integrity checks for all the binary combinations for the bits.
This you will do for “0” integral and “1” integral values.
This test needs to be done only once.
Most importantly, the data bus connection should be properly secured.
· Address Line Integrity Test
This test is carried out by randomly writing to a memory location and thereafter reading back from it for verification.
For instance, you select a memory location then write a unique data set to it.
Then, you read from the addressed location to verify the retrieved data.
Retrieval of inconsistent data signifies a fault with your SRAM IC’s address lines.
Which Material is SRAM IC made of?
You find that SRAM chips are made from silicon. Silicon is a hard and brittle material with semiconductive properties.
The transistors in SRAM IC cells are made from metal-oxide semiconductors while the package enclosure is usually plastic or ceramic material.
Besides, the connecting pins on SRAM chip packages are made from gold or tin.
The pins provide an electrical connection to the chip.
As you can see, to get a clear picture of what an SRAM IC is, you must understand everything highlighted in this guide.
I hope you got the answers to your questions.
However, if you have inquiries or questions about something I did not capture here – you can talk to us.