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Product Attributes

Introduction

ALD810019/ALD910019 are members of the ALD8100xx (quad-channel) and ALD9100xx (dual-channel) Supercapacitor Auto Balancing MOSFET (SAB™ MOSFET) family. SAB MOSFETs are fabricated using production-proven EPAD technology, designed to address voltage and leakage current balancing of series-connected supercapacitors. 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.

As shown in the Operating Electrical Characteristics table, the ALD810019 provides a unique, precise set of operating voltage and current characteristics for each of its four SAB MOSFET devices. It can be used to balance up to four series-connected supercapacitors. The ALD910019 has its own unique, precise operating electrical characteristics for each of its two SAB MOSFET devices, suitable for up to two series-connected supercapacitors.

Each SAB MOSFET features a precise gate threshold voltage in Vt mode, defined as 1.90V when the gate-drain-source terminals (VGS = VDS) are connected together at a drain-source current of IDS(ON) = 1μA. In this mode, the input voltage VIN = VGS = VDS. Varying VIN produces output current IOUT = IDS(ON) characteristics, forming an effective variable resistance whose value varies exponentially with VIN. When this VIN is connected across each series supercapacitor, it balances the voltage and current of each supercapacitor within its rated limits.

When VIN = 1.90V is applied to the ALD810019/ALD910019, the IOUT is 1μA. When VIN increases by 100mV to 2.00V, IOUT increases approximately 10×. For the ALD910019, when VIN further increases to 2.12V (2.14V for the ALD810019), IOUT increases 100× to 100μA. Conversely, when VIN decreases by 100mV to 1.80V, IOUT drops to one-tenth of its previous value, i.e., 0.1μA. A further 100mV reduction in input voltage will bring IOUT down to 0.01μA. Therefore, when the ALD810019/ALD910019 SAB MOSFET is connected across a supercapacitor charged to below 1.70V, it consumes essentially no power.

When the ALD810019/ALD910019 is connected across a supercapacitor, the voltage-dependent characteristics of its on-resistance effectively control the rise of overvoltage across the supercapacitor. In a series-connected supercapacitor stack, when the voltage of one supercapacitor rises, the voltages of the others decrease, with the supercapacitor exhibiting the highest leakage current having the lowest voltage. The SAB MOSFETs connected across these supercapacitors will present complementary, inverse current levels, contributing virtually no additional leakage current beyond that generated by the supercapacitors themselves.

Features

• Simple and cost-effective to use
• Factory-trimmed precision
• Automatic leakage current regulation and balancing
• Effective supercapacitor charge balancing
• Balance up to 4 supercaps in a single IC package
• Supports 2-cell, 3-cell, and 4-cell series supercap balancing
• 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 supercaps
• Leakage current is an exponential function of cell voltage
• Active current range from <0.3nA to >1000μA
• 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
• Scaled supercapacitor banks and arrays