Abstract: This article introduced one kind of use serial
clock chip DS1302 design monolithic integrated circuit application
system and its the software and hardware realization plan.
Key word: Timer; Monolithic integrated circuit;
DS1302
Intelligent water meter synopsis
--- The traditional intelligent water meter when
controls the water valve opens and shuts off, generally uses the
method is the internal installation lithium battery. The lithium
battery merit is the weight light, the energy big, 自放?rate is
low and so on. For all that, because the intelligent water meter
has not all designed the overcharging electric circuit, after the
lithium battery uses the certain time, will be unable for the control
circuit to provide the energy, will be able not but to replace the
battery. Visits for the user replacement battery or the water
meter, this produces the factory and the running water company
regarding the water meter said all is a tedious matter. More
dangerous is, the battery capacity is insufficient the situation
appears is stochastic, if not precise and prompt monitor battery
capacity, will be unable reliably to shut off the water valve, will
create is unable to cost, to run away situation appearance and so on
water phenomenon. This was the interior has installed the
lithium battery intelligent water meter fatal shortcoming, directly
affected its promotion and the use. In view of this question,
the water meter produced the factory to design very many plans, for
example: Reduces the power loss as far as possible, when static
state controls leaks the electric current in 10 mu A, guaranteed the
battery was allowed above the long-term usage 5 years, this proposed
to the electric circuit design and the primary device shaping a higher
request, increased the design difficulty and the end product
examination working procedure, if added on the reliable battery
capacity monitor electric circuit, also could cause the cost increase. New solution
--- In order to solve the bottleneck problem which this
restriction intelligence water meter develops, had many factories to
attempt one kind of brand-new plan, that is (Super-Capacitor) replaces
the lithium battery with the super electric capacity to apply to the
intelligent water meter. The super electric capacity is only
then the volume production one kind of passive component, the
performance is situated between between in recent years the battery
and the ordinary electric capacity, has the electric capacity the big
electric current fast sufficient flashover characteristic,
simultaneously also has the battery the stored energy characteristic,
and the repetition service life is long, when electric discharge uses
the electron between the motion conductor (but not to depend upon
chemical reaction) the releasing current, thus provides the power
source for the equipment, see Figure 1
Super electric capacity characteristic
--- Take American Cooper (Cooper) the super electric
capacity as the example, carries on the comparison with the battery,
has the following some obvious characteristics:
* The ultra low series equivalent resistance (ESR), the power
density (Power Density) is above lithium ion battery dozens of times,
suits the big electric current electric discharge, (a 4.7F electric
capacity could release above instantaneous electric current 18A) is
the water meter control electrical machinery valve or the solenoid
valve reliably opens has provided the safeguard.
* The ultra long life, the sufficient electric discharge is
bigger than 500,000 times, is lithium ion battery 500 times, is the
nickel hydrogen and nickel cadmium cell 1,000 times, if sufficiently
discharges 20 times every day to the super electric capacity, the
long-term usage may amount to for 68 years.
* May the big electric current charge, the sufficient discharge
time short, is simple to the charging circuit request, non- memory
effect.
* Exempts the maintenance, may seal.
* The temperature range width -40 ~ +70 ? the ordinary
battery is -20 ~ 60 ? Plan description
--- Compares with the internal installation lithium
battery intelligent water meter, this kind of plan is with the super
electric capacity replace lithium battery seal in the water meter,
simultaneously outside meets the dry cell battery power supply.
Usually the dry cell battery provides the water meter electric
circuit to need the energy and to the super electric capacity charge,
when needs to open the water valve, meets the dry cell battery by
outside to provide the energy to open the water valve; When
needs to shut off the water valve, if outside meets the battery not to
be able to provide the energy to shut off the water valve, then the
super electric capacity in this moment will provide the energy to shut
off the water valve. If the identical water tank, usually saves
the water, when cutting off the water supply only then plays the role.
--- Chart 2 is the application schematic drawing. In the
normal condition, the battery through resistance R, two levels manages
D1 to the load and the super electric capacity charge. The
resistance R function is limits the electric current oversized,
because the super electric capacity 内阻 is very small, when charge
the electric current comparatively greatly possibly creates the
battery damage. Two levels manage D1 to prevent the reverse
electrical current. When the battery voltage excessively is low,
or when sudden power failure (for example takes down battery),
continues by the super electric capacity for the electric circuit to
provide the power source, simultaneously, the super electric capacity
saves the energy sufficiently shuts off the valve.
Plan merit
--- This kind of plan obviously surpassed before design,
merit as follows:
* Separates the battery from the water meter, thus may not
consider the battery life to the water meter the influence, greatly
lengthened the water meter period of revolution.
* On the other hand, the super electric capacity big electric
current flashover characteristic has safeguarded the reliability which
the water valve shuts off, meets the dry cell battery electric
quantity insufficiency when outside, still could use saves the energy
shuts off on the super electric capacity the water valve.
* Before pursues constantly leaks the electric current target,
mainly is for safeguard the battery the service life, after changes to
the super electric capacity, leaks the electric current target to
change no longer importantly. If the battery capacity is
insufficient, the user may replace as necessary. Thus, not only
causes the circuit design to simplify, reduces the product to leave
the plant the examination working procedure, but also causes the
product cost reduction.
Conclusion
--- This kind of plan has overcome the present stage
intelligence water meter shortcoming, had found a new way for the
intelligent water meter development. At present domestic had
many water meters production factory to apply this plan, the practice
proved that, it is practical feasible. |
