What is CellularRAM^® Memory?

Our CellularRAM memory is pseudo-static DRAM with an asynchronous/page and burst interface, hidden refresh operation, and SRAM pin compatibility, which makes it a convenient and effective solution, designed specifically for mobile applications.

DRAM is a specific kind of random access memory that is  structurally simple—typically with one or two transistors and capacitors per bit—and it refreshes a memory cell's charge at regular intervals. Like DRAM, CellularRAM memory stores one bit of information in each of its millions of memory cells and refreshes these memory cells at regular intervals. But like SRAM, CellularRAM devices don't require external refresh support and use less power than standard DRAM.

If you want specific information about moving from SRAM to CellularRAM memory, including a discussion of power supply considerations, ball assignments, controller interface, and configurations, read our tech note,
TN-45-17: CellularRAM® Devices Replacing Single- and Dual-CE# SRAM.

Burst A/D MUX CellularRAM^® for Cost-Sensitive Mobile Markets

Our burst A/D MUX CellularRAM pseudo-static DRAM leverages all of the key performance advantages of our CellularRAM memory, but with a 30% reduction in controller pin count, simplifying controller designs, lowering system design costs, and shortening design-cycle times. Burst A/D MUX products are the perfect memory solution for handsets targeted at emerging markets and other battery-powered applications where low power consumption is an important consideration. We offer our burst A/D MUX products in die form because they make excellent companion devices for NOR Flash and are ideal for MCPs.

We've also prepared several technical notes to help you make a good decision about integrating a burst A/D MUX device into your next design.

• TN-45-04: CellularRAM Multiplexed Async/Burst Operation Discusses multiplexing a non-multiplexed CellularRAM device at the substrate level.
• TN-45-06: Density Migration for x16 Multiplexed PSRAM Introduction Explains what you will need to account for when you migrate a burst multiplexed device from 16Mb through 64Mb.
• TN-45-10: Designing Applications with the x16 Burst A/D Multiplexed Interface Describes differences between a burst non-A/D MUX and burst A/D MUX device.

What are the benefits of CellularRAM technology?

CellularRAM technology's multiple benefits include:

• backward compatibility with standard asynchronous SRAM devices
• DRAM technology with an SRAM interface
• higher densities and performance
• lower cost per bit than current SRAM devices

What are the specific features that distinguish the CellularRAM family from existing SRAM architectures?

6T-SRAM is most commonly used in densities of 2/4/8Mb in cell phone designs. It features 70ns/85ns random cycle times with a bandwidth of ~30 MB/s in a x16 configuration. Active power consumption at 1.8V is 25mA. CellularRAM devices significantly exceed today’s low-power 6T-SRAM in density and bandwidth, while keeping active power consumption at equally low levels. CellularRAM products feature a random cycle time of 70ns at 1.8V, and allow a peak bandwidth of 208 MB/s in burst mode.

What are the target markets and applications for CellularRAM devices?

CellularRAM products target handsets, but can be used anywhere cache or buffered memory is required.

What densities and configurations of CellularRAM does Micron offer?

Micron offers 16Mb, 32Mb, 64Mb and 128Mb densities in the Async/Page and Async/Page/Burst configurations. Micron offers all densities of CellularRAM in wafer form as KGD (Known Good Die). In wafer form, Micron also offers the Burst A/D multiplexed configuration.

What is CellularRAM memory?

CellularRAM memory is a family of pseudo-SRAM (PSRAM) products that are backward compatible with 6T (six-transistor) SRAM and early generation Async or Page PSRAM. CellularRAM offers a complete new set of devices with innovative functionality burst, providing an evolutionary path to pseudo SRAM.