button battery cr2032 Knowledge: button battery cr2032 Technology for Portable Electronic Devices

　　Today's button battery cr2032 technology in portable electronic equipment includes several aspects such as power detection algorithm, button battery cr2032 charging algorithm and button battery cr2032 charging technology. As we all know, there are four types of rechargeable button battery cr2032 chemical reactions: nickel cadmium, nickel metal hydride, lithium ion and lithium polymer. As for portable electronic devices, although these four button battery cr2032 types have their own characteristics, they are different from the perspective of energy density and safety. Development and practice show that the advantages of lithium-ion batteries and lithium-polymer batteries have become ideal for small and long-running devices, such as laptops and hard drive-based PMPs. For portable electronic equipment engineers, the correct choice and application Good button battery cr2032 technology in portable electronic equipment is very important. This article will discuss this and analyze its application with examples. Today's button battery cr2032 technology in portable electronic equipment includes power detection algorithm, button battery cr2032 charging algorithm and button battery cr2032 charging technology. aspect. As we all know, there are four types of rechargeable button battery cr2032 chemical reactions: nickel cadmium, nickel metal hydride, lithium ion and lithium polymer. As for portable electronic devices, although these four button battery cr2032 types have their own characteristics, they are different from the perspective of energy density and safety. Development and practice show that the advantages of lithium-ion batteries and lithium polymer batteries have become ideal choices for small and long-running devices, such as laptops and hard drive-based PMPs. For portable electronic equipment engineers, the correct choice and application button battery cr2032 technology is very important for good portable electronic equipment. This article will discuss this and analyze its application with examples.

　　button battery cr2032 Knowledge: button battery cr2032 Technology for Portable Electronic Devices

　　Preface

　　Today's button battery cr2032 technology in portable electronic equipment includes several aspects such as power detection algorithm, button battery cr2032 charging algorithm and button battery cr2032 charging technology. As we all know, there are four types of rechargeable button battery cr2032 chemical reactions: nickel cadmium, nickel metal hydride, lithium ion and lithium polymer. As for portable electronic devices, although these four button battery cr2032 types have their own characteristics, they are different from the perspective of energy density and safety. Development and practice show that the advantages of lithium-ion batteries and lithium polymer batteries have become ideal choices for small and long-running devices, such as laptops and hard drive-based PMPs. For portable electronic equipment engineers, the correct choice and application button battery cr2032 technology is very important for good portable electronic equipment. This article will discuss this and analyze its application with examples.

　　1. button battery cr2032 charging algorithms for trickle charging, fast charging and stable charging

　　Depending on the energy requirements of the end application, a button battery cr2032 pack may contain up to 4 lithium-ion or lithium-polymer cells in a variety of configurations, with a major power adapter: direct adapter, USB port or car charging device. Regardless of differences in cell count, cell configuration, or power adapter type, these button battery cr2032 packs all have the same charging characteristics. So their charging algorithms are the same. The best charging algorithm for lithium-ion and lithium-polymer batteries can be divided into 3 stages: trickle charging, fast charging and stable charging.

　　*Triple flow charging. Used to charge deeply discharged cells. When the cell voltage is below approximately 2.8V, it is charged with a constant current of 0.1C.

　　*Fast charging. When the cell voltage exceeds the threshold of trickle charging, the charging current is increased for fast charging. Fast charging current should be lower than 1.0C.

　　*Stable voltage. During fast charging, once the cell voltage reaches 4.2V, the voltage stabilization phase begins. At this time, charging can be interrupted by the minimum charging current or timer, or a combination of the two. When the minimum current is lower than approximately 0.07C, charging can be interrupted. The timer relies on a preset timer to trigger the interrupt.

　　Advanced button battery cr2032 chargers often come with additional safety features. For example, if the cell temperature exceeds a given window, usually 0℃--45℃, charging will be suspended. Except for some very low-end devices, the lithium-ion/lithium polymer button battery cr2032 charging solutions currently on the market all integrate or have external components to charge according to the charging characteristics. This is not only to achieve better charging results, but also It is also for safety.

　　2. Lithium-ion/polymer button battery cr2032 charging solution

　　Charging solutions for lithium-ion/polymer batteries are different for different numbers of cells, cell configurations, and power supply types. There are currently three main charging solutions: linear, Buck (step-down) switching, and SEPIC (boost and buck) switching.

　　2.1 Linear scheme

　　When the charger input voltage is greater than the open circuit voltage after a fully charged button battery cr2032 cell plus sufficient headroom, it is best to use a linear solution, especially when the 1.0C fast charging current is not much larger than 1A. For example, MP3 players usually have only one button battery cr2032 cell with a capacity ranging from 700 to 1500mAh, and the fully charged open circuit voltage is 4.2V. The power supply of the MP3 player is usually an AC/DC adapter or a USB interface, and its output is a regular 5V). At this time, the linear solution charger is the simplest and most efficient solution. Figure 2 shows the linear scheme of the lithium-ion/polymer button battery cr2032 charging scheme. The basic structure is the same as the linear voltage regulator.

　　*Charger application examples of linear solutions - dual-input Li+ charger and smart power selector MAX8677A. The MAX8677A is a dual-input USB/AC adapter linear charger with built-in SmartPowerSelector for portable devices powered by a rechargeable single-cell Li+ button battery cr2032. The charger integrates all the power switches needed to charge the button battery cr2032 and external sources and switch loads, so no external MOSFETs are required. The MAX8677A is ideal for portable devices such as smartphones, PDAs, portable multimedia players, GPS navigation devices, digital cameras, and digital camcorders.

　　The MAX8677A can operate from independent USB and AC adapter power inputs or from either input. When external power is connected, the smart power selector allows the system to be connected without a button battery cr2032 or with a deeply discharged button battery cr2032. The intelligent power selector automatically switches the button battery cr2032 to the system load, using the unused portion of the system's input power to charge the button battery cr2032, making full use of limited USB and adapter input power. All required current sensing circuitry, including integrated power switches, are integrated on-chip. The DC input current limit is adjustable up to 2A, while both DC and USB inputs support 100mA, 500mA, and USB suspend modes. Charging current is adjustable up to 1.5A, supporting a wide range of button battery cr2032 capacitances. Other features of the MAX8677A include thermal regulation, overvoltage protection, charge status and fault outputs, power-good monitoring, button battery cr2032 thermistor monitoring, and a charge timer. The MAX8677A is available in a space-saving, thermally enhanced, 4mm4mm, 24-pin TQFN package and is specified to operate over the extended temperature range (-40 to +85°C).

　　2.2Buck (step-down) switching solution

　　When the 1.0C charging current is greater than 1A, or the input voltage is much higher than the fully charged open circuit voltage of the button battery cr2032, the Buck or step-down solution is a better choice. For example, in hard disk-based PMPs, single-cell lithium-ion batteries are usually used, with a fully charged open circuit voltage of 4.2V and a capacity ranging from 1200 to 2400mAh. Nowadays, PMP is usually charged with a car kit, and its output voltage is between 9V and 16V. A relatively high voltage difference (minimum 4.8V) between the input voltage and the button battery cr2032 voltage will make the linear solution less efficient. This low efficiency, coupled with a 1C fast charge current greater than 1.2A, can create serious heat dissipation issues. To avoid this situation, the Buck plan should be adopted. Figure 3 is a schematic diagram of the Buck charger solution for lithium-ion/polymer batteries. The basic structure is exactly the same as that of the Buck (step-down) switching voltage regulator.

　　2.3SEPIC (boost and buck) switching scheme

　　In some devices using 3 or even 4 lithium-ion/polymer cells in series, the input voltage of the charger is not always greater than the button battery cr2032 voltage. For example, a laptop computer uses a 3-cell lithium-ion button battery cr2032 pack, the fully charged open circuit voltage is 12.6V (4.2Vx3), and the capacity ranges from 1800mAh to 3600mAh. The input power supply is either an AC/DC adapter with an output voltage of 16V, or a car kit with an output voltage between 9V and 16V. Obviously, neither linear nor Buck solutions can charge this button battery cr2032 pack. This requires the use of the SEPIC solution, which can work when the output voltage is higher than the button battery cr2032 voltage, and can also work when the output voltage is lower than the button battery cr2032 voltage.

　　3. Power detection algorithm

　　Many portable products use voltage measurements to estimate remaining button battery cr2032 power. However, the relationship between button battery cr2032 voltage and remaining power changes with discharge rate, temperature, and button battery cr2032 aging, making this method's error rate the highest it can be. up to 50%. Increasing market demand for products that last longer requires system designers to demand more precise solutions. Using a fuel gauge to measure how much power is being charged or drained from the button battery cr2032 will provide a more accurate button battery cr2032 estimate over a wide range of application power levels.

　　3.1 One of the application examples of power detection algorithm, the design of a fully functional button battery cr2032 pack for single and double button battery cr2032 portable applications

　　*Power detection principle. A better power detection meter must at least have button battery cr2032 voltage, button battery cr2032 pack temperature and current, measurement method) a microprocessor 9a) and a set of proven power detection algorithms. The bq2650x and bq27x00 are complete fuel gauges with an analog-to-digital converter (ADC) that measures voltage and temperature and an ADC that measures current and charge sensing. These fuel gauges also feature a microprocessor that executes Texas Instruments' fuel gauge algorithms. These algorithms compensate for factors such as self-discharge, aging, temperature and discharge rate of lithium-ion batteries. The chip contains a microprocessor to save the host system processor from these calculation burdens. The power meter can provide information such as the remaining power status. The bq27x00 series products also provide the remaining runtime (RunTimetoEmpty). The host can query this information from the power meter at any time. , and then notify the user of button battery cr2032 information through LED indicators or screen display. The power meter is very convenient to use. The system processor only needs to configure a 12C or HDQ communication driver.

　　*button battery cr2032 pack circuit description. Figure 4(a) shows a typical button battery cr2032 pack application circuit with an optional identification function IC. Depending on the fuel gauge IC used, the button battery cr2032 pack needs to have at least three to four external terminals. The VCC and BAT pins are connected to the button battery cr2032 voltage to power C and measure the button battery cr2032 voltage. A small sense resistor is connected to the button battery cr2032 ground terminal, allowing the high-impedance SRP and SRN inputs of the fuel gauge to monitor the voltage across the sense resistor. The current flowing through the sense resistor can be used to determine how much power is being charged or discharged from the button battery cr2032. When selecting the detection resistor value, designers must consider that the voltage across the resistor cannot exceed 100mV. A too low resistance value may cause errors when the current is small. The board layout must ensure that the connections from SRP and SRN to the sense resistor are as close as possible to the sense resistor terminal) In other words, they should be Kelvin wired.

　　The HDQ pin requires an external pull-up resistor, which should be located on the host or main application side so that the fuel gauge can enable the sleep function when the button battery cr2032 pack is disconnected from the portable device. It is recommended that the pull-up resistor value be 10k.

　　*button battery cr2032 pack identification. There is a growing problem of cheap, counterfeit batteries that may not contain the safety protection circuitry required by the OEM. Therefore, a genuine button battery cr2032 pack may contain the identification circuit shown in Figure 4(a). When the button battery cr2032 is to be authenticated, the host sends a query value (challenge) to the button battery cr2032 pack containing IC (bq26150, which functions as a cyclic redundancy check (CRC)). The CRC contained in the button battery cr2032 pack will be summed according to this query value, and the value in the IC The built-in CRC polynomial calculates this CRC value. CRC is completed based on the query command of the host and the CRC polynomial defined secretly in the IC. The host will also calculate the CRC value and compare it with the calculation result of the button battery cr2032 pack to determine whether the authentication is successful. Once the button battery cr2032 passes the certification, the bq26150 will issue instructions to ensure that the data line communication between the host and the fuel gauge is normal. When the button battery cr2032 connection is interrupted or reconnected, the entire qualification process is repeated.

　　3.2 The second example of application of power detection algorithm can be applied to new ICs of various general-purpose power meters.

　　Today, many manufacturers can provide a wide variety of fuel gauge ICs, from which users can select appropriate functional devices to optimize the product's cost performance. Utilizing the fuel gauge to store measured button battery cr2032 parameters, this decoupled architecture allows users to customize the fuel measurement algorithm within the host computer, thereby eliminating the cost of an embedded processor in the button battery cr2032 pack. On this occasion, a typical analysis will be made of the DS2762 chip of the company Dallasesemicconductor. The structure of a new type of separate fuel meter IC is shown in Figure 5(a).

　　*DS2762 application features

　　DS2762 is a single-cell lithium button battery cr2032 fuel gauge and protection circuit integrated in a tiny 2.46mm2.74mm flip-chip package. Due to the internal integration of high-precision resistors for power detection, this device is very space-saving. Its small size and unparalleled high level of integration make it ideal for mobile phone button battery cr2032 packs and other similar handheld products, such as PDAs. Integrated protection circuitry continuously monitors the button battery cr2032 for overvoltage, undervoltage and overcurrent faults (during charging or discharging). Unlike stand-alone protection ICs, the DS2762 allows the host processor to monitor/control the conduction state of the protection FET. In this way, system power control can be achieved through the DS2762's protection circuitry. The DS2762 can also charge a deeply drained button battery cr2032, providing a current-limited recovery charging path when the button battery cr2032 voltage drops below 3V.

　　DS2762 can accurately monitor button battery cr2032 current, voltage and temperature, and its dynamic range and resolution meet the test standards of any popular mobile communication products. The measured current is integrated against an internally generated time base to achieve power metering. Fuel metering accuracy is improved through real-time, continuous automatic offset correction. The built-in sense resistor eliminates resistance changes caused by manufacturing processes and temperature, further improving the accuracy of the fuel gauge. Important data is stored in 32-byte, lockable EEPROM and 16-byte SRAM is used to store dynamic data. All communication with the DS2762 occurs through a 1-Wire, multi-node communication interface, minimizing button battery cr2032 pack to host wiring. Its main features are) Single-cell lithium button battery cr2032 protector) High-precision current (fuel metering), voltage and temperature measurement) Optional integrated 25m sense resistor, each DS2762 is individually fine-tuned) 0V button battery cr2032 recovery charging) 32 bytes can be added Lock EEPROM, 16-byte SRAM, 64-bit ROM)

　　1-Wire, multi-node, digital communication interface) supports multi-button battery cr2032 pack power management and implements system power control through protection FETs) The power supply current in sleep mode is only 2?A (maximum)) The power supply current in operating mode is 90?A ( Max)) 2.46mm 2.74mm flip-chip package or 16-lead sub-SSOP package, both available with or without detectionResistors) are available with evaluation boards.

　　4 Conclusion

　　Applying the button battery cr2032 technology of portable electronic equipment is the basis for selecting lithium-ion batteries, lithium polymer batteries and their chargers. How to choose correctly must also depend on the specific requirements of portable electronic equipment.

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