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MOSFETs Automatically Balance Supercapacitors in High Voltage Commercial Applications

MOSFETs Automatically Balance Supercapacitors in High Voltage Commercial Applications

Advanced Linear Devices Inc. (ALD) announced a family of Supercapacitor Auto Balancing (SAB™) MOSFETs designed for high voltage commercial applications to regulate and balance leakage currents for each cell used in a series stack of two or more.

Supercapacitors are ideal components for commercial high energy storage applications that require high-voltage, high-current drive. They are suited for a broad range of applications such as Internet of Things, consumer products, white goods, office automation, long term battery backup and energy harvesting.

In high voltage systems ranging from 5-to-400 volts, the leakage current of supercapacitors used in a stack can be automatically balanced by connecting one or more SAB MOSFETs across each cell. Leakage current in the stack is sensed by each SAB MOSFET, which in turn uniquely increases or decreases the equivalent shunt resistance thereby balancing the stack. Supercapacitor cell balancing is critical to prevent damage to cells through over voltage that can dramatically shorten supercapacitor operating life to days, weeks or months if efficient cell balancing circuitry is not employed.

Each device in the SAB MOSFET ALD810016-22/ALD910016-22 family is effective for balancing up to 4 supercapacitor cells with a single IC package. Starting with two cells the devices can balance an unlimited number of supercapacitor cells stacked in a series. The standard operating temperature range of 0°C to 70°C is suitable for most commercial systems.

The ALD810016-22/ALD910016-22 SAB MOSFET family dissipates near zero leakage current and contributes no additional power dissipation to the capacitor stack. SAB MOSFETs, when connected across these supercapacitor cells, exhibit complementary opposing current levels, resulting in little or no additional leakage currents other than that resulting from the supercapacitor leakage specification. They provide a superior circuit design alternative to passive or active balancing methods by offering automatic active leakage current regulation. As an alternative to op-amp based balancing schemes, the SAB MOSFET arrays can reduce board space, and lower cost while enhancing system performance and extending component lifespan.

The ALD810016-22/ALD910016-22 SAB MOSFET family offers different threshold voltages for various supercapacitor operating voltages and leakage current characteristics. The new device family covers a range of operating voltages from 1.6V to 2.8V and leakage current ranges from <0.3nA to >3000µA.

Available in both quad and dual packages, the ALD810016-22/ALD910016-22 SAB MOSFETs are made with ALD's precision EPAD® technology.

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