Renesas Technology has announced the development of the R1WV6416R Series of 64 Mbit Advanced Low-Power SRAM (Advanced LPSRAM) products with high LPSRAM capacity, and the R1LV3216R Series of 32 Mbit Advanced LPSRAM products with compact chip size. Sample shipments of the 32 Mbit products will begin in April 2008, and of the 64 Mbit products in July, in Japan. These two new series use exclusive memory cell technology to achieve smaller chip sizes and soft error free. They will be available in different packages and specifications, such as access time, for a total of twelve 64 Mbit products and eight 32 Mbit products to meet the requirements in fields including industry, office equipment, consumer electronics, automotive systems, and communications equipment.
The main features of the R1WV6416R Series and R1LV3216R Series are: low-power SRAM with large capacity of 64 Mbits- the new 64 Mbit low-power SRAM products each comprise a stack of two compact 32 Mbit Advanced LPSRAM chips in a single package thus providing high capacity. They provide larger-capacity low-power SRAM for high-performance systems and meet reduced space requirements; wide package lineup to meet a range of requirements- to accommodate a variety of applications, these two new series are being offered in several different packages: TSOP I (48-pin), μTSOP (52-pin), and for 64 Mbit products FBGA (48-ball). The TSOP I and μTSOP packages have the same dimensions as those of previous 16 Mbit products, and the ball layout of the FBGA package is signal pin compatible. This enables customers to increase memory capacity while continuing to use their existing layout designs; high reliability with soft error free and latchup free- Advanced LPSRAM uses a stacked capacitor memory cell configuration. It virtually eliminates soft errors caused by alpha radiation or high-energy neutron radiation. In addition, this memory cell configuration avoids the unintended formation of a parasitic thyristor, which can generate spurious current flows and cause latchups. Elimination of soft errors and latchups provide high reliability.
Advanced LPSRAM products that are currently in mass production include 4 Mbit and 16 Mbit products, as well as 32 Mbit products comprising two 16 Mbit chips stacked in a single package. The two new series provide increased capacity with compact single-chip 32 Mbit products and 64 Mbit products comprising two 32 Mbit chips stacked in a single package. The R1WV6416R Series of 64 Mbit Advanced LPSRAM products and the R1LV3216R Series of 32 Mbit Advanced LPSRAM products are available with access times of 55 ns (nanoseconds) or 70 ns, and in TSOP I (48-pin), μTSOP (52-pin), or (for 64 Mbit products) FBGA (48-ball) packages.
The package of the TSOP I (48-pin) products is identical to that of current 16 Mbit products, and the package of the μTSOP (52-pin) is identical to that of current 8 Mbit, 16 Mbit, and 32 Mbit products. FBGA (48-ball) products have a ball layout that is backward compatible with that of current 4 Mbit, 8 Mbit, 16 Mbit, and 32 Mbit products. Advanced LPSRAM eliminates soft errors through the use of stacked capacitors and reduces the surface area of each memory cell by using a vertical configuration in which the stacked capacitors are formed in a layer above the transistors. The SRAM cells use polysilicon TFTs as P-channel load transistors. By forming these in a layer above the other transistors and reducing the number of transistors underneath, the memory cell surface area is reduced. Thus the 32 Mbit R1LV3216R Series has small chip size.
The transistors underneath comprise driver and access transistors with only an N-channel. Elimination of soft errors and latchups provide good reliability. Advanced LPSRAM requires no refreshes and therefore uses less power. This makes it suitable for low-power applications that use batteries for data backup. Typical applications include: consumer products- electronic dictionaries; industrial equipment- vending machines, POS terminals, automated ticket gates; office equipment- multifunction copiers; automotive systems- car navigation systems; and communications systems- switchboards and routers.
