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Wireless Battery Charger Chip for Smart-Card Applications
Presented By:
Franz-Xaver Arbinger, Peter Spies, Günter Rohmer,
Fraunhofer IIS, Am Wolfsmantel 33, 91058 Erlangen, Germany
Abstract “
A chip for inductive battery charging is presented, which needs no external components except an antenna to capture the energy from an electromagnetic field. The integrated system blocks are a front-end to limit and rectify the induced alternating voltage and a charge regulator with three control loops for the current, the voltage and the temperature. The external antenna forms a resonance circuit with the on-chip capacitor. The resonance frequency of the front end is 13.56 MHz, so it is compatible to the well known smart-card standard. In the electromagnetic field of commercial reader systems the chip produces an output current to charge a lithium battery with the mandatory constant-current-constantvoltage (cccv) charge profile. This architecture is implemented to charge lithium cells at a current of 4 mA up to a cell voltage of 4.2 volts. The target application are high-end smart-cards with secondary batteries. The chip, fabricated in a 0.8 µm BICMOS-technology, includes two contacts for the antenna and two for the battery. The chip size is 1.5 mm x 2.5 mm. Also present are additional pads for testing the chip and for using a dcvoltage source for charging. The measurements of the chip show good results and the whole function has been evaluated by charging the lithium accumulators. The operating current of the IC is approximately 1 mA.
Read full report
http://iis.fraunhofer.de/Images/paper_wi...-73299.pdf
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please send me the complete report of smart note taker.
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09-10-2010, 11:22 AM
[attachment=5468]
ABSTRACT
This report covers the basis and design of the wireless battery charger. The wireless charger will convert the RF/ microwave signal at 900 MHz frequency into a DC signal, and then store the power into an AAA battery. The project is divided into 3 parts: transmitter, antenna, and charging circuit. A complete discussion of the specifications of the battery charger is provided after data measurements. This report also includes component list, financial, data results, and other key information.
INTRODUCTION
Portable electronic devices are very popular nowadays. As the usage of these portable electronic devices is increasing, the demands for longer battery life are also increasing. These batteries need to be recharged or replaced periodically. It is a hassle to charge or change the battery after a while, especially when there is no power outlet around. Therefore, our team is inspired to design a wireless battery charger. This wireless battery charger is expected to eliminate all the hassles with today’s battery technology. As for now, there are no known companies that are developing the wireless battery charger. This means that there might be a good opportunity in the market for this type of product. Moreover, people tend to spend more money for convenience that meets the price. The outlook of this device is supported by the above predictions. It would be convenient not having to worry about charging or changing the batteries and still have a working device. The advantage of this device is that it can wirelessly charge up the batteries which can save time and money in a long run for the general public. Base on this concept, the design team has come up with a new way to charge the batteries wirelessly. The project is to make a prototype device that converts microwave signals to DC power. Once the prototype has been proved to be working, it is possible to implement this prototype into other applications such as in television remote control, fire alarm, clock, and places that are far to reach to change battery.
DESIGN OVERVIEW
This wireless battery charger is designed to operate at 900 MHz. In this project, a power transmitter acts as the power source. It will transmit power to the receiver side. And then, the rectifier circuit in the receiver will convert the RF/ microwave signal into DC signal. After the DC signal is produced, the charging circuit will store the power into the battery. Here is the block diagram of the overall design.
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LEAD-ACID BATTERY CHARGER WITH
VOLTAGE ANALYSER
INTRODUCTION
Nowadays maintenance-free lead-acid batteries are common in vehicles, inverters, and UPS systems. If the battery is left in a poor state of charge, its useful life is shortened. It also reduces the capacity and rechargeability of the battery. For older types of batteries, a hygrometer can be used to check the specific gravity of the acid, which, in turn, indicates the charge condition of the battery. However, you cannot use a hygrometer for sealedtype maintenance-free batteries. The only way to know their charge level is by checking their terminal voltage. The circuit presented here can replenish the charge in a battery within 6-8 hours. It also has a voltage analysing circuit for quick checking of voltage before start of charging, since overcharging may damage the battery. The voltage analyser gives an audio-visual indication of the battery voltage level and also warns about the critical voltage level at which the battery requires immediate charging. The charger circuit consists of a standard step-down 12V AC (2-amp) transformer and a bridge rectifier comprising diodes D1 through D4. Capacitor C1 smoothes the AC ripples to provide a clean DC for charging the battery. The battery voltage analyser circuit is built around the popular quad op-amp LM324 that has four separate op-amps (A through D) with differential inputs. Opamps have been used here as comparators. Switch S2 is a pushswitch, which is pressed momentarily to check the battery voltage level before charging the battery. The non-inverting terminals of op-amps A through D are connected to the positive supply rail via a potential divider chain comprising resistors R1 through R5. Thus the voltage applied to any non-inverting input is the ratio of the resistance between that non-inverting terminal and ground to the total resistance (R1+R2+R3+R4+R5). The resistor chain provides a positive voltage of above 5V to the non-inverting inputs of all op-amps when battery voltage is 12.5V or more. A reference voltage of 5V is applied to the inverting inputs of op-amps via 5V zener diode ZD1. When the circuit is connected to the battery and pushswitch S2 is pressed (with S1 open), the battery voltage is sampled by the analyser circuit. If the supply voltage sample applied to the non-inverting input of an op-amp exceeds the reference voltage applied to the inverting inputs, the output of the op-amp goes high and the LED connected at its output lights up.
For more information about this article,please follow the link:
http://asahadownload/UOTg5OTg-
http://asahaebook/UOTg5OTg-/LEAD-ACID-BATTERY-CHARGER-WITH-VOLTAGE-ANALYSER.pdf#PDF Ebook
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Smart Cards: Technology for Secure Management of Information
Rajat Moona
Computer Science and Engineering
IIT Kanpur
Plastic Cards
Visual identity application
Plain plastic card is enough
Magnetic strip (e.g. credit cards)
Visual data also available in machine readable form
No security of data
Electronic memory cards
Machine readable data
Some security (vendor specific)
for more::->
http://authorstreamPresentation/latha-124511-smart-cards-smartcards-entertainment-ppt-powerpoint/
http://gpcetmcaemeraldsppt/Smart%20Cards.ppt
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