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Product Attributes

Introduction

SAB MOSFETs are fabricated using production-proven EPAD technology, designed to address voltage and leakage current balancing of supercapacitors connected in series. Supercapacitors, also known as ultracapacitors or supercaps, can achieve leakage current balancing in series connections by connecting one or more devices across each supercapacitor cell to prevent overvoltage.

The ALD810026 provides a unique, precision set of operating voltage and current characteristics for each of its four SAB MOSFET devices. It can be used to balance up to four supercapacitors connected in series. The ALD910026 provides a unique set of precision operating electrical characteristics for each of its two SAB MOSFET devices, suitable for up to two supercapacitors connected in series.

Each SAB MOSFET features a precision gate threshold voltage in Vt mode of 2.60V when the gate-drain-source terminal (VGS = VDS) is connected together at a drain-source current IDS(ON) = 1μA. Different VIN levels produce output current IOUT = IDS(ON) characteristics, forming an effective variable resistance whose value varies exponentially with VIN. When this VIN is connected across each supercapacitor in series, the voltage and current of each supercapacitor can be controlled within its limits.

The voltage-dependent on-resistance characteristics of the ALD810026/ALD910026 are highly effective in controlling overvoltage rise across connected supercapacitors. In a series supercapacitor stack, when the voltage across one supercapacitor rises, the voltages across the others decrease, with the supercapacitor having the highest leakage current exhibiting the lowest voltage. The SAB MOSFETs connected across these supercapacitors present complementary opposing current levels, adding virtually no additional leakage current beyond that generated by the supercapacitors themselves.

Features

• Simple and cost-effective to use
• Factory precision trimmed
• Automatic adjustment and balancing of leakage current
• Effective supercapacitor charge balancing
• Balance up to 4 supercapacitors per IC package
• Supports balancing of 2-cell, 3-cell, and 4-cell series-connected supercapacitors
• Scalable to larger supercapacitor banks and arrays
• Near-zero additional leakage current
• Zero leakage current at 0.3V below rated voltage
• Balances series and/or parallel connected supercapacitors
• Leakage current is an exponential function of cell voltage
• Active current range from < 0.3 nA to > 1000 μA
• Always active with fast response time
• Minimized leakage current and power consumption

Applications

• Series supercapacitor cell leakage current balancing
• Energy harvesting
• Long-term backup battery with supercapacitor output
• Zero-power voltage divider at selected voltage
• Matched current mirrors and current sources
• Zero-power mode maximum voltage limiter
• Extended supercapacitor banks and arrays