Advanced Linear Devices ALD910025SALI

ALD810025/ALD910025 are members of the ALD8100xx (quad-channel) and ALD9100xx (dual-channel) Supercapacitor Auto Balancing MOSFET (SAB™ MOSFET) families. SAB MOSFETs are fabricated using production-proven EPAD® technology, designed to address voltage and leakage current balancing in series-connected supercapacitors. Supercapacitors, also known as ultracapacitors or supercaps, are balanced against leakage current by connecting one or more devices across each supercapacitor cell to prevent overvoltage. The ALD810025 provides each of its four SAB MOSFET devices with a unique, precisely matched set of operating voltage and current characteristics, enabling balancing of up to four series-connected supercapacitors. The ALD910025 provides each of its two SAB MOSFET devices with a unique set of precisely matched electrical characteristics, suitable for up to two series-connected supercapacitors. Each SAB MOSFET operates in Vt mode with a precise gate threshold voltage of 2.50V, defined when the gate-drain-source terminals are connected together (VGS = VDS) at a drain-source current of IDS(ON) = 1μA. Different VIN levels produce output current IOUT = IDS(ON) characteristics, forming an effective variable resistance that varies exponentially with VIN. When this VIN is applied across each series-connected supercapacitor, the voltage and current of each supercapacitor can be balanced within its limits. When VIN = 2.50V is applied to the ALD810025/ALD910025, the IOUT is 1μA. Increasing VIN by 100mV to 2.60V causes IOUT to increase approximately tenfold. A further increase to VIN = 2.72V (2.74V for the ALD810025) results in a hundredfold increase in IOUT, reaching 100μA. Conversely, reducing VIN by 100mV to 2.40V decreases IOUT to one-tenth of the previous value, i.e., 0.1μA. A further 100mV reduction in input voltage causes IOUT to drop to 0.01μA. Therefore, when the ALD810025/ALD910025 SAB MOSFET is connected across a supercapacitor charged below 2.30V, virtually no power is consumed. The voltage-dependent on-resistance characteristics of the ALD810025/ALD910025, when connected across a supercapacitor, effectively control excessive voltage rise across it. In a series-connected 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 will exhibit complementary and opposing current levels, generating virtually no additional leakage current beyond that produced by the supercapacitors themselves.

• Simple and cost-effective to use
• Factory precision trimmed
• Automatic regulation and balancing of leakage current
• Effective supercapacitor charge balancing
• Single IC package balances up to 4 supercapacitors
• 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
• Operating current range from < 0.3 nA to > 1000 μA
• Always active with fast response time
• Minimized leakage current and power consumption

• 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
• Maximum voltage limiter in zero-power mode
• Scalable supercapacitor banks and arrays