PSRAM,as its name implies,is a kind of memory disguised as SRAM.Essentially,it combines the memory core of DRAM(high density and low cost)with a self-refresh circuit and an SRAM-compatible interface.From the perspective of external devices(such as CPU or MCU),it is like a standard SRAM chip-it can read and write data without complicated refresh management,giving addresses and commands.But inside the psram chip,data is stored in a single transistor cell similar to DRAM in the form of capacitive charge.
 

Yingshang PSRAM chip adopts the same high-density memory core(1T1C)as DRAM,so that the storage capacity far exceeds that of SRAM at the same cost.At the same time,the chip integrates the necessary refresh logic to"encapsulate"the tedious refresh task.Externally,it presents a standard SRAM interface protocol.This means that the system designer can use it like SRAM,without adding additional memory controller to deal with refresh,which greatly simplifies the hardware design and software driver development.The SPI interface PSRAM chip introduced by Yingshang can be connected with only a few signal lines,and the number of pins is only one third of that of traditional parallel DRAM,which greatly saves PCB space and simplifies wiring.
 

Taking a typical SPI interface PSRAM chip as an example,its workflow is as follows:When the CPU of system on a chip(SoC)needs to access an address mapped to the PSRAM area,the address signal is not directly sent to the PSRAM particles.The CPU will first visit its internal memory management unit,recognize that the address belongs to the external PSRAM space,and then forward the request to the integrated or external PSRAM controller.According to SPI protocol,the controller will send the access request(address and read-write command)to the PSRAM chip through the serial bus.After reading or writing data internally,the PSRAM chip returns the data to the controller through SPI bus and finally to the CPU.For CPU,the whole interaction process is no different from accessing the traditional parallel SRAM,which realizes seamless and transparent access.
 

Based on this unique structure,Yingshang PSRAM chip shows many advantages in application:

①Compared with SRAM,PSRAM can provide more storage space at significantly lower cost.

②The refresh mechanism integrated in②psram chip is more efficient than that of traditional DRAM relying on external controller.At the same time,PSRAM supports power saving modes such as deep sleep,and standby power consumption is extremely low.

③PSRAM gets rid of the dependence on complex DRAM controller,and any processor with basic parallel or serial interface can be easily connected.

④Yingshang's QSPI/OSPI interface PSRAM products support four or even eight times data rate transmission.In serial interface mode,its transmission speed can easily exceed 3Gbps,which is enough to meet the bandwidth requirements of graphics buffering,audio processing and other applications.


Keywords:psram