The ALD810025 by Advanced Linear Devices is a member of the ALD8100xx family of Supercapacitor Auto Balancing (SAB™) MOSFETs. It excels in voltage and leakage-current regulation for series-connected supercapacitors. By integrating one or more devices across each supercapacitor stack, this MOSFET ensures exact voltage and current limits, effectively preventing over-voltages.

The chip delivers its own unique operating voltage and current characteristics for each of four SAB MOSFET devices. Its standout feature is the precision gate threshold voltage in the Vt mode, set at 2.50V. When the gate-drain source terminals (VGS = VDS) are connected at a drain-source current of IDS(ON) = 1µA, the gate threshold voltage stabilizes at 2.50V. The differential input voltages (VIN = VGS = VDS) generate an Output Current IOUT = IDS(ON), transforming the device into a variable resistor that adjusts exponentially with VIN. This ensures that each supercapacitor in a series is balanced within specified voltage and current limits.

For example, applying a VIN of 2.50V results in an IOUT of 1µA. Increasing VIN by 100mV to 2.60V amplifies IOUT tenfold. Further increasing VIN to 2.74V escalates IOUT to 100µA. In contrast, reducing VIN by 100mV to 2.40V decreases IOUT to one-tenth, and a subsequent reduction by another 100mV brings IOUT down to 0.01µA. This chip exhibits near-zero power dissipation when connected across a supercapacitor charging to less than 2.30V.

The ALD810025's voltage-dependent characteristic on-resistance is designed to counter excessive voltage rise across a supercapacitor efficiently. In series-connected supercapacitor stacks, this feature plays a crucial role in maintaining balance across the supercapacitors, ensuring minimal additional leakage currents.

FEATURES & BENEFITS:

• Simple and economical to use
• Precision factory trimmed
• Automatically regulates and balances leakage currents
• Scalable for larger supercap stacks and arrays
• Achieves near-zero additional leakage currents
• Zero leakage at 0.3V below rated voltages
• Balances series and/or parallel-connected supercaps
• Active current ranges from 1000µA
• Always active with fast response time
• Features a zero-power voltage divider at selected voltages
• Equipped with matched current mirrors and current sources
• Includes a zero-power mode maximum voltage limiter

Available to order at Digi-Key and Mouser (product number ALD810025SCL) in 16-pin SOIC packages starting at $4.48 each per 50.