The electric power parameter monitor meter mainly uses in records power consumer each hour when the electricity consumption and the integral point the electric current, the voltage spurt value, these data must save in the nonvolatile storage, when needs time is delivered after the public opinion line to the power supply Control section, carries on processing. The superintendent through these data may prompt, understand accurately in the area of jurisdiction various power consumer detailed uses electricity the situation, with the aim of making a more reasonable decision-making, enables the limited electric power resources to play the major role, simultaneously uses in the electric tube principle method a new stair.
Usually in the situation, the power cut is inevitable, for does not destroy in system’s data, must use the nonvolatile storage, if uses EEPROM or dodges the fast memory (Flash Memory) to take the storage medium is obviously inappropriate, because they write the operation to need dozens of milliseconds, specially must use SRAM which in the timely request high situation the battery supports, it both has the RAM read-write speed, and has the characteristic which the ROM power failure data does not lose. Moreover the use battery supports SRAM, but also some merit is may lay aside some dense symbols in SRAM, plays the hardware encryption the role. But the battery supports SRAM has the data in the actual use process not to be unreliable, easy to lose. Moreover the battery easy to receive the environment factor the influence, for example humidity, vibration. RAMTRON Corporation develops the poss ferroelectric random access memory success volume production has solved the battery problem. It has the following characteristic:
1. non-volatility: After the power failure, the data can preserve for 10 years, all products are the technical grades.
2. scratches writes the number of times to be many: 5V power supply FRAM scratches writes the number of times 1010 times, low voltage FRAM scratches writes the number of times to not to have the time limit.
3. the speed is quick: The serial port main line’s FRAM CLK frequency reaches as high as 20M, and does not have 10MS to write the waiting cycle, and mouth access speed 70NS.
4. the power loss is low: The quiescent current is smaller than 10UA, the read-write electric current is smaller than 150UA.
5.5V power supply FRAM surpasses in the read-write number of times 10,000,000,000 can also from now on with the RAM same work, is only the data cannot preserve.
The memory module constitutes by Fm1808, the concrete electric circuit sees this corporate design guide. Fm1808 selects patches or strips of land as worth saving for seed the pin /CS signal and SRAM has the difference, SRAM is the low level selection slightly, but Fm1808 is the drop along the selection. (saw chart) power failure the data protection electric circuit through to control /CS to guarantee on electricity and power failure period forbade Fm1808 to carry on writes the operation. Fm1808 has the 32K byte space. If must be larger capacity, but outside expands. Will promote the 1Mbit poss ferroelectric random access memory hopefully in next year’s the first half of the year.
RAMTRON has model of multi-purpose chip FM3808 in addition (integrated real-time clock, watch-dog, voltage examination, 32K FRAM), outside needs sets at the battery or the electric capacity, but only supplies the clock power source. It may substitute for SRAM which the battery supports the clock EEPROM plan.
The ferroelectricity technology is one kind of brand-new technology, used big reduced the line board area in this system, reduced electric circuit’s complexity, guaranteed that the data the unreliability, was helpful to supply power the Control section to make a more reasonable decision-making.
