This section provides an overview for memory ics as well as their applications and principles. Also, please take a look at the list of 4 memory ic manufacturers and their company rankings.
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A memory IC is a type of semiconductor device mainly used to store data in various types of computers, such as microcontrollers, SOCs, PCs, and servers.
A memory IC is broadly classified into ROM and RAM.
ROM (read-only memory) is basically read-only memory, but it can also be written to under certain conditions. It also retains stored data even when the power is turned off.
ROM is divided into PROM (programmable ROM) and mask ROM. On the other hand, a mask ROM is used only as a read-only ROM, which cannot be rewritten after the program is burned and stored in the semiconductor manufacturing process.
RAM is a device that can be read/written any number of times, but the stored data is lost when the power is turned off.
All types of memory ICs, ROM and RAM, are used as devices for storing programs and data to control the CPUs installed in various devices.
ROM is used to store control programs for microcontrollers and operating systems for personal computers because the internal data is retained even when the power is turned off. Basically, it is a read-only memory, but there are also types of ROMs that can be rewritten by applying a special voltage. These include OTPROM, EEPROM, and flash memory, which will be discussed later.
Compared to ROM, RAM is more complex to control and requires a procedure called refresh within a certain period to retain data. RAM is mainly used as a temporary storage area for data to perform calculations or when processing large amounts of data, since the stored data is lost when the power is turned off.
ROM is divided into PROM and mask ROM. Furthermore, several types of PROMs are available for different applications.
As the name suggests, OTPROM is a type of PROM that can be written only once, while EPROM is a PROM that can be written multiple times.
EPROMs include UV-EPROMs, which can be erased by ultraviolet light, and EEPROMs and flash memories, which can be erased electrically.
RAM, on the other hand, is divided into SRAM and DRAM, and DRAM is further divided into several types: SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, and DDR4 SDRAM.
As mentioned above, RAM requires a control called refresh to retain data. SDRAM (Single data rate RAM) is RAM that can transfer one word of data (read/write) per clock cycle.
DDR SDRAM (Double data rate RAM), on the other hand, has a structure of two words of data transfer per clock cycle, which means it is twice as fast as SDRAM.
DDR2 SDRAM has twice the processing speed of DDR SDRAM, DDR3 SDRAM has twice the processing speed of DDR2 SDRAM, and DDR4 SDRAM has twice the processing speed of DDR3 SDRAM.
*Including some distributors, etc.
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Infineon Technologies AG (Infineon) is headquartered in Neubiberg, Germany. Infineon designs, develops, manufactures, and markets semiconductors and related system solutions worldwide. Infineon’s automotive segment produces microcontrollers, discrete power semiconductors, IGBT modules, industrial microcontrollers, power and radar sensor ICs, SiC diodes, MOSFETs voltage regulators, comfort electronics, infotainment, powertrain, and security products. Industrial Power Control segment provides bare dies, discrete IGBTs, and driver ICs among other components. Power & Sensor Systems segment offers gas and pressure sensors, MEMS microphone chips, control ICs, and GaN power switches among others.
ROHM Semiconductor was incorporated in 1940 and is headquartered in Kyoto, Japan. ROHM manufactures and sells electronic components worldwide. ROHM operates through the segments ICs, discrete semiconductor devices, and modules. ROHM provides ICs comprising memory, amplifiers and linear, power management, clocks and timers, switches and multiplexers, logic, data converters, sensors and MEMS, display drivers, motor/actuator drivers, interfaces, communication and speech synthesis LSI, audio and video, and microcontrollers. ROHM also offers discrete semiconductor products include MOSFETs, bipolar transistors, and diodes; power devices, including power transistors and diodes, SiC power devices, IGBT, and IPM; passive devices, such as resistors, and conductive polymer and tantalum capacitors; and various modules among others.
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