The SABMB810028 PCBs are designed to automatically control leakage current in data centre, industrial automation, public utility, and transportation applications. 

The boards are built with the company’s ALD810028SCLI supercapacitor auto-balancing (SAB) MOSFETs which provide balancing for 2.8, 3.0 and 3.3V supercapacitors arranged in a series stack. Balancing is achieved by equalising the leakage current of each cell. The SAB MOSFET arrays used in each board provide the industry’s most scalable, low-power solution, claims the company. Additionally, the MOSFETS balance each cell through low levels of leakage current without exposure to supercapacitor charge/discharge voltage levels for cells of 3000F or more.

“New, higher voltage supercapacitors being introduced to address the energy storage needs of data centers and industrial automation require high reliability to meet very demanding standards for back-up power systems,” explains Robert Chao, president and founder, Advanced Linear Devices. “These boards provide the ideal platform for balancing high voltage supercapacitors through a low-voltage, low leakage and low current controlling method in a small and scalable form factor.”

The boards are rated for -40 to 85°C and are available with voltage ratings of 2.8v, with 1µA operating current, 3.0V (100µA) and 3.3V (1000µA).

According to the company, in many cases, the operating current is equivalent in magnitude to the leakage current of the supercapacitors.

Over-voltage is a leading cause of failure for supercapacitors. All supercapacitor cells in a stack of two or more need to be balanced, to prevent over-voltage. The SAB MOSFET(s) installed on the board prevent over-voltage, and the boards enable system engineers to test, evaluate, prototype or enter production volume. The company’s SAB MOSFET technology provides a circuit design that saves cost, when compared to other passive or active balancing schemes, and has design space options for supercapacitor leakage currents. 

The boards are scalable to meet the demand for multiple supercapacitor cells in modules required to meet today’s energy storage needs. Engineers looking to meet the needs of new 700V systems, for example, could arrange 64 boards together to ensure safe voltage balancing, advises the company.

The SAB MOSFET boards allow supercapacitor cell charging and discharging currents to pass through the cells directly, bypassing SAB MOSFETs mounted on the board with near zero additional leakage current. This, says the company, is a superior alternative to other methods where additional power dissipation used by the circuitry far exceeds the supercapacitor energy burn caused by leakage currents.