New Compact CMOS Li-Ion Battery Charger Using Charge-Pump Technique for Portable Applications

Dept. of Electron. Eng., Nat. Taipei Univ.
Circuits and Systems I: Regular Papers, IEEE Transactions on (Impact Factor: 2.4). 05/2007; 54(4):705 - 712. DOI: 10.1109/TCSI.2007.890605
Source: IEEE Xplore


This paper presents a new compact CMOS Li-Ion battery charger for portable applications that uses a charge-pump technique. The proposed charger features a small chip size and a simple circuit structure. Additionally, it provides basic functions with voltage/current detection, end-of-charge detection, and charging speed control. The charger operates in dual-mode and is supported in the trickle/large constant-current mode to constant-voltage mode with different charging rates. This charger is implemented using a TSMC 0.35-mum CMOS process with a 5-V power supply. The output voltage is almost 4.2 V, and the maximum charging current reaches 700 mA. It has 67.89% power efficiency, 837-mW chip power dissipation, and only 1.455times1.348 mm2 in chip area including pads

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    • "III. HARVESTER SYSTEM DESIGN Nowadays, charging circuits (e.g., a power converter) using a charge pump have gained popularity in wireless sensor systems for their smaller form factors, simpler structures, and faster charging rate [14]–[16]. According to Sokal [16], the fastest and most efficient method to charge a capacitor is to use the maximum peak switch current. "
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    ABSTRACT: Micro-solar energy harvesting systems have achieved efficient operations through maximum power point tracking (MPPT) and maximum power transfer tracking (MPTT) tech- niques. However, they may have chargers with relatively high power thresholds, below which they have 0% efficiency. As a result, these harvesters either require much larger panels than necessary, or they fail to sustain extended periods of poor weather. To address this problem, we propose to generalize MPTT to MCZT, for Maximum Charging Zone Tracking, to expand the zones of effective charging. To cover the wide dynamic range of solar irradiation, we propose a programmable charge pump driven by a direct digital synthesizer (DDS). In addition, we dynamically reconfigure the topology of multiple supercapacitors to maximize charging efficiency and minimize voltage-dependent leakage. Experimental results from simulation and measurement show that under the high solar irradiance of 1000 , our MPTT part achieves 40%-50% faster charging time than one without MPTT; and under low solar irradiation of 300 , the boost-up operation of our system enables fully charging the supercapacitors, thereby extending the harvesting time zone from 10:00 am-07:10 pm to 8:20 am-8:00 pm even on a sunny day, all with an MPTT overhead of 1.5 mW.
    IEEE Journal on Emerging and Selected Topics in Circuits and Systems 09/2011; 1(3):391-402. DOI:10.1109/JETCAS.2011.2167274 · 1.52 Impact Factor
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    • "The Charger controller has duty of creating a feasible electro power for rechargeable battery and it must identify the point that is stopping charging to avoid rechargeable battery explosion [1] [2] [6] [9] [10]. The Constant-Current and Constant-Voltage (CC-CV) is used most broadly [1] [2] [3] [4] [6] [7] [9] [10] [11] [13] but its function is cannot give the customer all of their need. Therefore, the fuzzy control, are applied to approach better battery charging performance [20] [21] [17]. "

    Proceedings of SPIE - The International Society for Optical Engineering 01/2011; · 0.20 Impact Factor
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    • "Previous Li-ion charger designs, however, often suffer from two significant problems. First, unnecessarily complex control circuitry [2], [3] is often employed to manage battery charging at the expense of circuit area and power consumption. Additionally, many circuits require a sense resistor in order to detect end-of-charge [4], [5]. "
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    ABSTRACT: This paper describes an ultra-compact analog lithium-ion (Li-ion) battery charger for wirelessly powered implantable medical devices. The charger presented here takes advantage of the tanh output current profile of an operational transconductance amplifier (OTA) to smoothly transition between constant current (CC) and constant voltage (CV) charging regimes without the need for additional area- and power-consuming control circuitry. The proposed design eliminates the need for sense resistors in either the charging path or control loop by utilizing a current comparator to detect end-of-charge. The power management chip was fabricated in an AMI 0.5 μm CMOS process, consuming 0.15 mm<sup>2</sup> of area. This figure represents an order of magnitude reduction in area from previous designs. An initial proof-of-concept design achieved 75% power efficiency and charging voltage accuracy of 99.8% relative to the target 4.2 V.
    Circuits and Systems (ISCAS), Proceedings of 2010 IEEE International Symposium on; 07/2010
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