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Serial SRAM and Serial NVSRAM

Serial SRAM

Serial SRAM is a standalone volatile memory that offers designers an easy and inexpensive way to add more RAM to their application. These 8-pin low-power, high-performance SRAM devices have 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 functions. These devices are available from 64 Kbit up to 1 Mbit in density and support SPI, SDI and SQI™ bus modes.

Serial NVSRAM

Serial NVSRAM 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. This 8-pin, SPI device supports unlimited instantaneous writes to the memory array, making it ideal in applications such as meters, data loggers, data recorders or black boxes. These devices are available in 512 Kbits and 1 Mbit densities.

Serial SRAM Videos

RAM Expansion Options

There have traditionally been two ways to increase an application’s RAM:

  1. Use a larger microcontroller. This option is less attractive if you must buy a larger, more expensive micro just to get more RAM.
  2. Use external parallel RAM. But, parallel RAM uses large packages and typically requires at least 16-20 I/Os.
SERIALRAMARROW
Serial SRAM now offers the flexibility to add RAM to a design without the disadvantages of a large microcontroller or parallel RAM and uses the simple 4-pin SPI interface. These devices also offer improved performance with the SDI and SQI interface that offers up to a 4x improvement in data rates.

Memory Product Comparison

 Serial
EEPROM
Parallel
EEPROM
OTP
EPROM
Serial
Flash
Parallel
Flash
Serial
SRAM
Serial
NVSRAM
Serial
EERAM
Density128 bit - 4 Mb64 Kb - 1 Mb256 Kb - 8 Mb512 Kb - 64 Mb1 - 64 Mb64 Kb - 1 Mb512 Kb - 1 Mb4 Kb - 1 Mb
Clock Frequency0.4 - 20 MHz70 ns45 ns20 - 104 MHz55-70 ns16 - 20 MHz16 - 20 MHz1 - 66 MHz
Cost/BitHighHighHighLowLowMediumMediumMedium
Read TimesMediumFastFastMediumFastMediumMediumMedium
Write TimesMediumFastN/AMediumFastInstantaneousInstantaneousInstantaneous
Pin Count2 to 8 pins28 and 32 pins28 to 44 pins8 pins32 and 48 pins8 pins8 pins8 pins
Data Retention200+ Years10 Years10 Years100+ Years100+ YearsVolatile20+ Years
(with battery)
100+ Years
Typ. Standby Current1 µA200 µA100 µA~15 µA~30 µA~4 µA~4 µA~40 µA
Voltage1.7 V - 5.5V2.7V,
5V
2.7V,
5V
1.65V - 1.95V,
2.7V - 3.6V,
2.3V - 3.6V
1.65V - 1.95V,
2.7V - 3.6V,
4.5V - 5.5V
1.65V - 1.95V,
2.5V - 5.5V
2.5V - 5.5V2.7V - 3.6V,
4.5V - 5.5V
Temperature-55°C to +150°C 1-55°C to +125°C-40°C to +85°C-40°C to +125°C 1-40°C to +85°C-40°C to +125°C-40°C to +85°C-40°C to +125°C 1
1. Selected densities