Boards automatically balance leakage current in supercapacitor series stacks used in evaluation, prototype and production systems

Linear Devices (ALD) announces the immediate availability of universal PCB
designed to automatically balance leakage currents and manage over voltage,
enabling ultra-low power usage in supercapacitors used in a series stack. The
board uses ALD’s SAB MOSFETs (SABMB16, SABMB8100XX, SAVMB9100xx) to balance the
leakage current in each individual supercapacitor cells from 0.1 F to 3,000 F.





The PCB is
designed to allow system engineers to test, evaluate, prototype or use in
production products. Supercapacitor balancing is required by cell manufacturers
when used in stacks of two or more. Balancing manages over-voltage limits, a
main cause of product failures.


MOSFET’s PCB balancing technology reduces leakage current enabling ultralow
power operation. Each device in the ALD8100XX/ALD9100XX SAB MOSFET provides a circuit
design alternative to passive or active balancing methods by offering automatic
active leakage current regulation and space and cost-saving alternative to
op-amp based balancing schemes.




The basic connection
diagram for use with three SAB MOSFET devices.



testing shows the ALD method of cell balancing extends the product life of
stacked caps. Applications for supercaps and this cell balancing technique include
energy harvesting, transportation, back-up power and automation.


SABMB16 / SABMB810025
/ SABMB910025 are universal application boards. The first two versions in the
series are SABMB810025 and SABMB910025. These are 2.5-V universal boards
allowing designers to select either the ALD810025 SAB MOSFETs or the ALD910025 SAB MOSFETs
installed. A third version is unpopulated to allow engineers to select the
appropriate SAB MOSFETs based on their specific design specifications. All
three options are delivered ready to use, designed for balancing any size
supercapacitors with little power dissipation. No user circuit design or
hardware engineering is necessary. 


the charging or discharging of supercapacitor currents pass through the
supercapacitors but do not pass through the SABMB16 boards or SAB MOSFETs
mounted on the PCB board. In many cases, the total additional leakage current
contributed by the PCB is approximately zero, or no more than a small
percentage of the highest supercapacitor cell leakage current in the stack. This
contrasts with other methods of balancing where the additional power
dissipation used by the balancing circuitry far exceeds the supercapacitor
power burn caused by its own leakage current.


is designed for ease of use as a plug-and play PCB for supercapacitors of 0.1 F
to 3,000 F. The average additional power dissipation due to DC leakage of the
supercapacitor is zero, which makes this method of supercapacitor balancing energy
efficient and suited for low loss energy harvesting and long-life battery
operated applications. Pricing starts at $33.34 each.