The folks at Microchip Technology (a well-known provider of microcontroller and analog semiconductors) have announced a family of 8- and 32-Kbyte stand-alone serial SRAM devices, which increase a system's available RAM memory by adding small, inexpensive external devices.
The 23A640, 23K640 (23X640), 23A256, and 23K256 (23X256) devices feature a familiar, industry-standard SPI interface and enable increased design flexibility, while reducing design and production costs, and time to market.
Many embedded applications require volatile RAM for temporary data storage, or for use as a scratchpad, for bulk processing and for math algorithms. In many cases, this RAM is embedded within the microcontroller (MCU). In the past, the most viable way to add more RAM was to buy a larger MCU, which could add unnecessary feature overhead and increase design costs. The only alternative was to add large, parallel-access RAM devices that use up large numbers of I/O pins.
Microchip's serial SRAM devices provide a simple, inexpensive way for designers to add more RAM to their application while keeping the same MCU, or even using a smaller one if replacing parallel external RAM with serial RAM. Additionally, the devices feature a bus speed of 20 MHz for fast access, and low operating and standby currents to help extend battery life. They are available in 8-pin packages but only use four MCU pins, compared with 16 to 24 pins for parallel RAM.
The 23A640 and 23A256 devices have an operating voltage range of 1.7 to 1.95V. The 23K640 and 23K256 devices have an operating voltage range of 2.7 to 3.6V. All of the devices are well suited for applications involving bulk data transfers; DSP and other math algorithms (e.g. FFT and DFT); audio/video, speech encoding, VoIP and Internet applications. Specific examples include applications in the consumer (Internet appliances, Internet radios and printers); industrial (utility meters, vending machines); and medical markets (portable patient-monitoring devices), among others.
Part numbers, pricing, and availability
Microchip's serial SRAM devices are all available in 8-pin SOIC, PDIP and TSSOP packages. In 10,000-unit quantities, the 23X640 devices are priced at $0.48 each for the SOIC package; $0.50 each for the PDIP package, and $0.51 each for the TSSOP package. The 23X256 devices are priced in 10,000-unit quantities at $0.90 each for the SOIC package; $0.91 each for the PDIP package, and $0.93 each for the TSSOP package.
Samples are available today at http://sample.microchip.com and volume-production quantities can be ordered today at www.microchipdirect.com. For further information, contact any Microchip sales representative or authorized worldwide distributor, or visit Microchip's Web site at www.microchip.com/SRAM.