Supercapacitors will typically operate at a normal working voltage but voltages that exceed the maximum for a prolonged period of time will cause harm to cell operating life. In terms of capacitance value, internal resistance, and leakage current, supercapacitors have different tolerances.
However, when two or more supercapacitors are connected, either parallel or in a series, these differences can cause cell voltage imbalances that must be balanced so that no single cell exceeds its maximum rated voltage.
Speaking about ALD's newest innovation, ALD's president and founder, Robert Chao, said, “The OVP board is the only commercially available balancing scheme that manages both over-voltage and leakage current. The circuit used on the board offers matched precision push-pull voltage/current action, which is ideal for cells with a minimal amount of energy loss.”
ALD's Over Voltage Protection PCBs
Equipped with ALD's proprietary ALD9100XX Supercapacitor Auto Balancing (SAB) MOSFET IC chip that specifies the circuit threshold or clamping voltage, the new over-voltage protection SABMBOVP2XX PCB series is designed to be compact, economical, and effective in balancing any size supercapacitors with little-to-no power dissipation. The SAB MOSFETS are ALD exclusive EPAD MOSFETs that address voltage balancing of multiple supercapacitor cells connected in series.
A SABMBOVP Advanced Linear Devices overvoltage protection PCB. Image Credit: Mouser.
The SABMBOVP contains two OVP circuits, each functioning as a precision voltage clamp with extremely high current gain characteristics. Inside each of two SABMBOVP circuits on the PCB, the internal voltages of the circuit are shifted so that the balancing output current from the SAB MOSFET is amplified to produce nominally 1mA of balancing (clamp) output current at VIN equal to the rated SAB MOSFET threshold voltage.
Both PCBs features include:
Super low output currents at input voltages below the threshold voltage
Precision threshold voltage setpoint
Extreme change of output current in response to changes in input voltage
Ultra-low-power for energy harvesting and battery-powered applications
Fully automatic over-voltage protection (no additional circuits or software)
A broad selection of threshold voltages for a variety of applications
Both PCBs measure just 15.24mm x 40.64mm and operate in a temperature range of -40 to +85°C. They are made with RoHS-compliant FR4 material and are supplied ready for mounting.