The LTC4425 features two operating modes: charge current profile or “normal” mode and LDO mode. The device’s charge current profile mode charges the top of the SuperCap stack to the input voltage V_IN with a charge current that varies inversely with the input-to-output voltage differential in order to prevent excessive heating. The LDO mode charges the stack to an externally programmed output voltage with a fixed charge current that is also externally programmable. Charge current is resistor programmable up to 2A (3A peak), and each capacitor is protected against overvoltage by internal shunts (2.45V/2.7V selectable). The LTC4425’s onboard current-limited ideal diode features extremely low 50mΩ on resistance to allow high forward current and to prevent back-driving of V_IN, making it suitable for a wide variety of high peak power battery and USB-powered equipment, industrial PDAs, portable instruments and monitoring equipment, power meters, SuperCap backup circuits and PC card/USB modems. The LTC4425’s automatic cell balancing feature maintains equal voltages across both cells, eliminating the need for balancing resistors while protecting each supercapacitor from overvoltage damage and minimizing current drain on the capacitors. The IC operates with a very low 20µA quiescent current when the output voltage is in regulation and draws only 2µA in shutdown from either V_IN or V_OUT, whichever is higher. The LTC4425 is available in two compact and thermally enhanced packages, a 12-lead, low-profile (0.75mm) 3mm x 3mm DFN package and a 12-lead MSOP package. The device operates over a -40°C to 125°C junction temperature range.