Buck-boost supercapacitor charger for fast charging

In order to prevent power source overload and minimise capacitor recharge time, the LTC3128 features an average input current limit that can be programmed up to 3A with ±2% accuracy. The supercapaacitor charger offers highly efficient active charge balancing to eliminate dissipative external ballast resistors, ensuring balanced operation and charging with mismatched capacitors, and less frequent recharge cycles.

As capacitors age and develop mismatched capacities, reliable operation is assured with a programmable maximum capacitor voltage clamp which actively monitors and enforces the voltage across each capacitor in the series stack. Low noise buck-boost topology enables the output supercapacitor to be charged whether above or below the input.  The low RDS(ON), low gate charge synchronous switches provide high efficiency conversion to minimise the charging time of storage elements.

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-3A programming range, and the individual maximum capacitor voltage can be set from 1.6-3.0V. Additionally, the LTC3128 features less than 1µA quiescent current from the voltage output in Burst Mode operation, accurate power good and power failure indicators and thermal overload protection.

Operating over a temperature range from -40 to 125°C, the LTC3128 is housed in compact, thermally enhanced 4x5mm 24-lead TSSOP and QFN packages. Pricing for the buck-boost supercapacitor charger starts from $3.95 (USD) each in 1,000 unit quantities.