Today's technological innovation demands high performance coupled with low environmental impact. These dual requirements are driving components of the semiconductor industry which informs many global businesses and consumer lives.
When considering system designs using semiconductor memory technologies, engineers have options including, but not limited to: battery backed static random access memory (BBSRAM); nonvolatile SRAM; ferroelectric random access memory (F-RAM); as well as other noVRAM technologies. It is the specific design considerations in each application - from factory automation and telecom to metering and medical technology - that determine the most appropriate memory choice.
Today's technological innovation demands high performance coupled with low environmental impact. These dual requirements are driving components of the semiconductor industry which informs many global businesses and consumer lives. When considering system designs using semiconductor memory technologies, engineers have options including, but not limited to: battery backed static random access memory (BBSRAM); nonvolatile SRAM; ferroelectric random access memory (F-RAM); as well as other noVRAM technologies. It is the specific design considerations in each application - from factory automation and telecom to metering and medical technology - that determine the most appropriate memory choice. This white paper addresses the functional and design differences between F-RAM and BBSRAM memories. Most specifically, the paper underscores how F-RAM offers a more future-forward environmental option with cost benefits, as well as less system complexity and maintenance. BBSRAM memory functions as a workhorse chip in many data logging applications. BBSRAM is easy to use, features high endurance, and fast writes. The biggest drawback is the fact that BBSRAM requires a battery. The battery poses environmental hazards, as well as design and system obstacles. As a mature semiconductor technology, F-RAM offers remarkably fast writes, high endurance and ultra-low power consumption. With native nonvolatility, F-RAM performs like an SRAM, but requires no battery. The absence of a battery offers engineers significant design and functional advantages. The lack of a battery also helps engineers save space in system designs. F-RAM saves costs by reducing the need to handle batteries separately to protect them against common soldering processes. In today's environmentally-conscious culture, F-RAM removes the requirement for battery replacement and disposal, contributing to a more eco-friendly solution with less pollution from battery by-products. The following comparative examination of F-RAM and BBSRAM highlights the functional and design differences between the two memory options, as well as their relative ecological, financial and performance influences.
BBSRAM requires a battery, typically a lithium energy source for power when external power fails or is turned off. Reflow solder is also not possible because batteries may leak or even explode. BBSRAM is also subject to Restriction of Hazardous Substances Directive (RoHS) compliance issues that can pose significant difficulties for design engineers. The RoHS initiative, adopted in February 2003, is a policy instituted by the EU that restricts the use of six hazardous materials in the manufacturing of certain electronic and electrical equipment. While the above noted challenges exist, BBSRAM is an optimal choice when there is a system requirement that demands accessing the memory at a rate of thousands of times per second. The static RAM in BBSRAM offers infinite endurance and is highly suited for applications that require continual read/write memory access. A typical BBSRAM board consists of the following components: 1. A low power SRAM 2. Voltage sensing circuit 3. Battery switchover circuit 4. A 3V lithium coin cell battery or 3.6V lithium thionyl chloride (Li-SOCI2) (depending on SRAM density and battery life time) 5. Optional RTC IC
With these component parts, a typical BBSRAM module production flow follows an approximate five-step process:
A summary of BBSRAM modules demonstrates:
BBSRAM modules in DIP from all vendors are pin compatible.
All BBSRAM modules guarantee 10-year battery life.
ECOPACK or PowerCap packages are offered to provide smaller form factor.
STMicroelectronics offers three BBSRAM modules in ECOPACK package for 64Kbit and 256Kbit
Maxim offers six BBSRAM modules in PCAP34 packages for 256Kbit, 1Mbit and 4Mbit.
ST, Maxim and TI all support 3.3V and 5V BBSRAM Modules, with speeds from 70ns to 200ns
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