Features

• ±2% Accurate Average Input Current Limit Programmable Up to 3A
• Programmable Maximum Capacitor Voltage Limit
• Active Charge Balancing for Fast Charging of Unmatched Capacitors
• Charges Single or Stacked Capacitors
• V_IN Range: 1.73V to 5.5V
• V_OUT Range: 1.8V to 5.5V
• <2μA Quiescent Current from VOUT When Charged
• Output Disconnect in Shutdown: <1μA I_Q Shutdown
• Power-Good Comparator
• Power Failure Indicator
• Thermally Enhanced 20-Lead (4mm × 5mm × 0.75mm) QFN and 24-Lead TSSOP Packages

Typical Application

Description

The LTC®3128 is a highly efficient, buck-boost DC/DC supercapacitor charger. It operates efficiently from input voltages above, below or equal to the output voltage. The LTC3128 incorporates accurate programmable average input current limit, active charge balancing and programmable maximum capacitor voltage. This combination of features makes the LTC3128 ideal for safely charging and protecting large capacitors in backup power systems. The input current limit and maximum capacitor voltage are each programmed using a single resistor. Average input current is accurately controlled over a 0.5A to 3A programmable range while the individual maximum capacitor voltage can be set from 1.8V to 3.0V.

Other features of the LTC3128 include <2μA quiescent current from V_OUT in Burst Mode®operation, accurate power-good and power failure indicators, and thermal overload protection. The LTC3128 is offered in low profile, thermally enhanced 20-Lead 4mm × 5mm × 0.75mm QFN and 24-Lead TSSOP packages.