Ultra-low voltage for SDRAMs

Available now from Sunrise Electronics, the Elpida 128Mbit Mobile RAM achieves super-low power operation at 1.8V, making it well suited for mobile applications such as cellular phones and PDAs.

Available now from Sunrise Electronics, the Elpida 128Mbit Mobile RAM achieves super-low power operation at 1.8V, making it well suited for mobile applications such as cellular phones and PDAs.

2.5V and 64Mbit versions are also available.

According to Akira Yabu, technical marketing and engineering manager for Elpida Memory (USA): "Mobile applications such as cellular phones and PDAs are beginning to process larger amounts of data and sound, including streaming video, due to the explosive growth of the Internet and the performance increases of wireless communications.

Such circumstances increase the need for fast, high-capacity RAM that consumes less power, and are the driving factors behind Elpida's application-specific Mobile RAM".

Elpida is the first manufacturer to roll out an SDRAM device featuring 1.8V supply voltage both for the memory core and the I/O circuits says Juergen Fuchs, Senior Manager Marketing at Elpida Memory (Europe).

The single voltage supply substantially simplifies the power management of latest mobile multimedia applications allowing longer operating time at smaller batteries.

Elpida has been actively involved in defining the Jedec standard specifications for low power SDRAMs since its inception, and Elpida's Mobile RAM Series is fully compliant with the new Jedec standard.

Elpida's Mobile RAM currently achieves a very low supply voltage (Vdd) operation of 1.8V +/-0.15V, reducing power consumption and extending battery life for mobile applications.

The operating currents for Elpida's 128 and 64Mbit Mobile RAM devices are 80 and 40mA, respectively, while the self-refresh current is an incredibly low 350uA for the 128Mbit device, and 250uA for the 64Mbit device.

This value offers substantial power savings (280 to 400%) compared with standard synchronous DRAMs that have a typical self-refresh current in the range of 1mA.

Elpida's Mobile RAM series also features a deep power down (DPD) mode to save power when the applications are not in use, and they have a partial array self refresh (PASR) that offers further power savings by managing the memory area to be refreshed within the device.

Because many mobile applications may become subject to extreme temperatures, Elpida designed the Mobile RAM to withstand a temperature range from -25 to +85C.

With this in mind, the devices also feature temperature compensated self-refresh (TCSR) that enables the Mobile RAM to adjust its refresh rate and power consumption at extreme temperatures to ensure device reliability.

The 128 and 64Mbit devices are manufactured using Elpida's proven 0.15um CMOS DRAM process technology.

They employ a synchronous interface and operate at 100MHz with CAS latency of 3.

The 2.5V versions are available at both 128 and 64Mbit densities, and they operate at a faster 133MHz, also with CAS latency of 3.

The I/O supply voltage is 1.8V +/-0.15V for both the 100 and 133MHz versions.

The 128Mbit devices have an internal organisation of four banks of 2M x 16bit, while the 64Mbit versions are organised as four banks of 1M x 16bit.

Both the 128 and 64Mbit versions come in tiny (8 x 8 x 1mm) 54-ball FBGA packages, enabling high-density component mounting for small mobile designs.

Denali Software has developed a library of simulation models for Elpida's Mobile RAM Series.

The models use Denali's Specification of Memory Architecture (SOMA) that enables designers to quickly integrate and verify the optimum usage of Elpida's Mobile RAM components within their new designs.

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