digital batteries

1 Introduction

The technology of RFID (Radio Frequency Identification, RFID) as a rapid, real time, accurate information gathering and processing of high technology and information based on standardization, has been recognized as World’s Top Ten key technologies of this century, one in production, logistics, retail, transportation and other miscellaneous industries prospects have wide application. The radio frequency identification technology has gradually become enterprises to improve management of the logistics supply chain, reduce costs, information Management Company, to participate in international economic circuit, strengthening the competitiveness tools and resources needed. IBM ThinkPad R52 battery IBM ThinkPad T40 battery

Based on RFID technology, the logistics supply chain implementation of the management system, requires a variety of RFID read-write device. Handheld RFID reader because of its easy to carry, easy to use features of applications in logistics are a big market. But now on the market for the majority of handheld devices RFID reader, the high energy consumption to extend their working hours, need for high capacity lithium battery power, how to provide a battery lithium fast charge a certain way, it is this need to explore a problem. In this paper, the design to meet RFID combined power DC-DC converter circuit, and the corresponding lithium battery fast charge circuit.

Two step-up circuits

A single voltage lithium battery supply of 3.7 V, the RFID read-write device operating voltage is 5V, so for RFID handhelds need a boost circuit. Dell Latitude D820 battery  Dell Latitude X1 battery

2.1 The basic principle of step-up circuit

Strengthening the principle of the circuit to stimulate the town as shown in literature. The realization of the circuit step-up process work can be divided into two stages: the process of loading and unloading process. The first step is the charging process: When the transistor Q1 turns on, the inductance load, the equivalent circuit shown in Figure 1 (a) as indicated. Power to the load inductor, a diode to prevent the capacitor discharges to the ground. As the input is DC, so inductor current on a certain ratio of the first linear increase in this ratio and the size of the inductor. As the inductor current increases, a large amount of energy stored in the inductor.

The second step is the discharge process: When the transistor Q1 cut-off, discharge the inductor, the equivalent circuit of Figure 2 (b) below. When the transistor Q1 into cutoff by the tower, because of the inductance to maintain the characteristics of current through the inductor will become equal to 0 in an instant, but slowly by the conclusions of the value of the charge becomes 0. The original routes have been disconnected, so that the F3172A PB995A new discharge circuit inductance, which began charging inductor capacitor voltage across the capacitor increases, this time the capacitor voltage can reach higher than the value of input voltage.

2.2 Boost Circuit

Step-up circuit using RichTek Technology RT9266B high efficiency DC-DC step-up chip RT9266B a low quiescent current, conversion efficiency, the external circuit is simple and so on. Chip with control loop adaptive PWM, the error amplifier, comparator and so on, through the circuit of external feedback, the output voltage can be adjusted all the necessary amplitude, with a precision high voltage. Circuit illustrated in Figure 2.

Figure 2 shows the circuit through the external inductor 10uH boost energy storage, using resistors R1 and R2 feedback control circuit output voltage pulse, using internal self-RT9266B VGP-BPS9A/B VGP-BPS9/S PWM Controller NMOS conduction pipe and closed to control the step-up circuit output current. Because the chip PWM controller adaptive, able to adapt to a greater load range.

With the boost circuit boosting polymer 3.7V 2000mAh Li-ion battery to 5V, the ripple of the output voltage is only 40mV, the maximum output current up to 500mA.

3 circuit load

3.1 Li-ion battery charging circuit of the basic principles of

Charging process of lithium can be divided into three stages: pre-load, load at a constant current and constant voltage. When the voltage of the lithium battery is less than the minimum charge voltage, then the first to enter the pre-charging phase, a small current (typically 10% of the current standard) to load the battery until the battery voltage reaches its minimum load voltage. At this stage of pre-charge to prevent over-lithium discharge directly after high-current damage constant load current. When the battery voltage is above the minimum charge voltage, charge in the phase of constant current load. Constant charging current is usually taken as 0.5C (C for the capacity of lithium batteries). When the voltage of the lithium PA3399U-2BAS PA3399U-2BRS battery is up to the standard voltage in constant voltage charging status, charging current is continuously reduced until the current is reduced to 100mA

Figure 2 shows the circuit through the external inductor 10uH boost energy storage, using resistors R1 and R2 feedback control voltage output circuit to stimulate the use of internal self-RT9266B the PWM controller to NMOS conduction pipe and closed to control the step-up circuit output current. Because the chip PWM controller adaptive, able to adapt to a greater load range.

With the boost circuit boosting polymer 3.7V 2000mAh Li-ion battery to 5V, the ripple of the output voltage is only 40mV, the maximum output current up to 500mA.

3 circuit load

3.1 Li-ion battery charging circuit of the basic principles of

Charging process of lithium can be divided into three stages: pre-load, load at a constant current and constant voltage. When the voltage of the lithium battery is less than the minimum charge voltage, then the first to enter the pre-charging phase, a small current (typically taking 10% of the current standard) to charge the battery up ‘that the battery voltage reaches its minimum load voltage. At this stage of pre-charge to prevent over-lithium discharge directly after high-current damage constant load current. When the battery voltage is above the minimum charge voltage, the charger into the charging phase constant current. Constant charging current is usually taken as 0.5C (C for the capacity of lithium A1060 M8403 batteries). When the voltage of the lithium battery is up to the standard voltage in constant voltage charging status, charging current is continuously reduced until the current is reduced to about 100 mA, load finished.

3.2 Li-ion battery charging circuit

Charging the lithium schematic circuit diagram of Figure 3, using the implementation of IT in the bq2057. bq2057 series is an advanced lithium-ion battery charge management IC for a single festival (4.1V or 4.2V) or dual (8.2V or 8.4V) Li-ion and lithium-polymer battery charging needs. BQ2057 can dynamically compensate for the internal resistance of lithium batteries to reduce the load time with optional battery monitoring, temperature, using temperature sensors to detect the battery in the temperature of the battery when the temperature the battery exceeds the target range BQ2057 to charge the battery, the internal integration of the constant voltage constant current device with a high / low side current sensing and a programmable charge current, the identification of state supported by the output of LED light or with the master interface, with automatic re-charge, the minimum charge current termination, low power consumption in sleep, stress and high precision (better than ± 1%) and other functions. Using the external charger circuit design chip is relatively simple and very suitable for compact portable electronics design needs.

The circuit through the NHS with COMP both ends of the DC-side sensing resistor R5 to set the PWM wave output for controlling the frequency of the transistor Q1 turn-on and cut, which would result in the maximum charge current control.

The tour through the actual testing, 3.7V 2000mAh Lithium-polymer BATCL50L  LCBTP03003 battery, a load current up to 810mA, 3 hours for the battery is full. Charging data in Table 1 below:

As can be seen from the table when the load circuit when the show full battery voltage of 4.12V measured with the standard 4.2V voltage difference between the 0.5V. The error reason is that the charging process, lithium battery life of current fluctuations in an instant when the current is below a certain threshold, bq2057 that charging is complete, turn-off circuit load.

4 Conclusions

This paper has developed a battery of the RFID device fast charge circuit, experimental data show that the use of RT9266B and bq2057 designed lithium battery charging and boost circuit to meet the needs of practical applications, and both chips to teach a small package size, the external circuit is simple and very appropriate for the management of portable power.

Innovations author: This paper has developed a battery of the RFID device fast charge circuit, the circuit can quickly use the handset to charge lithium batteries RFID.

Firstly, brief history of the development of mobile battery technology

With 3G networks in the accelerated process of global business, 3G users also appeared to grow substantially. Technically advanced enterprises 3G has a unique appeal, prompting users more often use a variety of multimedia services. Short period of 10 years, only to have a phone call from cells of all functions to be transformed into a variety of functions in one portable device. At the same time, the battery of mobile phones has grown complex and changes.

Early in the era of analog phones, batteries account for almost half the weight of the cell body also totaled 2 / 3 ratio. This undoubtedly affected the portability of cell phones. At that time, the batteries of mobile phones can be divided into three types: batteries nickel cadmium, nickel metal hydride and lithium-ion batteries, IBM ThinkPad T43 battery  IBM ThinkPad T60 battery.

Nickel-cadmium battery is composed of two plates, one with nickel hardware, and other materials system with cadmium, these two metals in batteries can produce reversible reaction, so that the battery can be recharged. Its greatest feature is firm, and talks long. The first “Big Brother” is the use of nickel-cadmium batteries.

Also known as green nickel-metal hydride batteries, because it contains no metal cadmium, do not pollute the environment. Its power reserve of more than nickel cadmium batteries for more than 30% to 50% of talk time and mobile phone can be extended by 30%.

Lithium-ion battery is a battery of high energy density, which, with the same size nickel-cadmium batteries, the batteries in nickel metal hydride over a larger reserve of power, lighter weight. Lithium-ion battery or a smart battery, it can be a smart charger dedicated to “speak” to achieve the shortest charging times and the highest cycle life and Dell Inspiron 8600 battery  Dell Inspiron 9200 battery capacity.

While mobile phones and small light weight to improve the performance of the development trend of mobile phone battery nickel-cadmium batteries of the transition at the beginning of the main phase of nickel metal hydride-based. With the rapid decline in the cost of lithium batteries, mainstream mobile phones currently on the market have been primarily using lithium-ion battery. Because the lithium Slim secondly, because the lithium batteries have greater capacity, greater density of power output, load faster.

In 2003, the use of lithium up to 90% (about 650 million group of demand) in 2004 increased to 94% (about 758 million group calls). Because there is no strong threat to short-term substitutes, if 2 ~ 3 years, lithium batteries can still maintain its edge in the market for mobile telephony is expected to 2005, the rate of ‘use will increase to 98%.

2, cell phone lithium battery of technological change

Lithium F3172A PB995A batteries for mobile phones mainly in liquid-based lithium-ion batteries, the recent development of lithium-ion cell phone battery should be around two main aspects:

First, the traditional liquid lithium-ion battery materials in positive and negative electrodes, electrolyte improvements. The increasing diversity of functions of mobile phone battery performance right to advance higher standards, has developed a new battery electrode materials will in future lithium-makers ion batteries for some time being competition. Currently, Japan Sanyo, and Sony took advantage of Ni, Co, Mn 3-component materials to produce high-capacity battery 4.4V, while the cathode active material Li (NiCoMn) 1/3O2 Honjo, at Japan, the company was sold, the cost of these materials LiCoO2 is approximately about half, therefore, their application will lithium batteries, especially lithium-Powered Battery to reduce the price of a degree.

Secondly, polymer lithium-ion batteries in cell phones will gradually increase the proportion of applications and will gradually replace the traditional Li-ion batteries, but before the launch of 3G, it is difficult for traditional lithium-ion batteries provide a threat.

Because lithium high energy density-ion battery, the overload condition, the increase in battery temperature, the excess energy, the PA3191U-3BRS PA3285U-2BRS battery internal pressure increases the risk of spontaneous combustion or explosion. Lithium batteries are generally liquid steel or aluminum for packaging, the battery of huge explosions.

In traditional liquid lithium-ion batteries lithium polymer developed from the battery (hereinafter referred to as poly-lithium battery), just be able to catch the performance of non traditional lithium batteries. Firstly, thank you film composite aluminum flexible packaging, as opposed to the hard shell packaging in terms of conventional lithium batteries, is not easy to explode, with more security. Secondly, poly-lithium batteries are lighter, thinner and higher capacity. Thirdly, in principle, poly-lithium battery can be designed in any shape, for cell phones and other mobile devices designed to provide excellent condition. Fourthly, the poly-electrolyte lithium battery using the gel or similar solid material, does not leak, thus reducing pollution.

This polymer lithium-ion battery energy density and load-discharge time, with lithium batteries traditional liquid are basically the same, its benefits are mainly reflected in the size and shape can be arbitrary. Poly-lithium batteries is difficult because of performance and price of ordinary lithium batteries caused by strong shocks, the current poly-lithium batteries accounted for 12% ~ 13% market share. However, as manufacturers continue to join, the price of lithium-polymer continues to decline, polymer lithium-ion battery in the current lithium-ion battery is a matter of time.