June 17, 2015 – Linear Technology Korea (CEO Hong Sa-gwak) announced the launch of a bidirectional programmable input current buck-boost supercapacitor charger (product name: LTC3110) that provides active charge balancing functionality suitable for one or two supercapacitors in series. The proprietary low-noise buck-boost topology performs the operation of two separate switching regulators, reducing size, cost, and complexity. The LTC3110 operates in two modes: backup and charge mode.

In backup mode, the device maintains a system voltage VSYS of 1.71V to 5.25V and is powered from the supercapacitor where energy is stored. Additionally, the supercapacitor storage input VCAP drops from 5.5V to 0.1V, providing a wide practical operating range. This ensures that all energy of the actually stored supercapacitor can be utilized, thus extending backup time or reducing storage capacitors. Alternatively, in charge mode where the main power system is activated, the LTC3110 can automatically or through user command change the direction of power flow to charge and balance the supercapacitor using the regulated system voltage. VCAP provides efficient charging functionality above or below VSYS through buck-boost PWM (pulse width modulator). The device also provides charge mode average input current limit functionality that can be programmed up to 2A with +/-2% accuracy, minimizing capacitor recharge time while preventing system power overload.

Active charge balancing of the LTC3110 removes the constant drain of dissipated external ballast resistors, ensures charging even with mismatched capacitors, and does not require frequent recharge cycles. Programmable maximum capacitor voltage regulation actively balances and limits each capacitor in a series stack up to half of the programmed value. Low RDS(ON), low gate charge synchronous switches provide high-efficiency conversion to minimize the charging time of storage elements. The LTC3110 is ideal for safely charging and protecting large-value capacitors in backup power applications such as RF systems using battery/capacitor backup, including servers and RAID systems.

Input current limit and maximum capacitor voltage of the LTC3110 are programmable via resistors. Average input current is actually controlled in the 0.125A to 2A programming range. Pin-selectable Burst Mode® operation improves light-load efficiency, reduces quiescent current to 40µA, and reduces shutdown current to less than 1µA. Other features of the LTC3110 include a 1.2MHz switching frequency minimizing external component size, thermal overload protection, two voltage supervisors for direction management and charge completion, and one general-purpose comparator with open-collector output interfacing with microcontroller or microprocessor.

The LTC3110 is offered in a compact 24-pin TSSOP and 4mm x 4mm QFN package with enhanced thermal performance, providing temperature range of E and I grades from –40°C to 125°C, and featuring up to 150°C for high-reliability H grade. The price for E-grade devices is $4.45 per unit based on 1,000-unit quantity. For more information, refer to www.linear.com/product/LTC3110.

2A Bidirectional Buck-Boost Supercap Charger

Product Features: LTC3110

-VCAP Operating Range: 0.1V to 5.5V

-VSYS Operating Range: 1.71V to 5.25V

-Automatic transition from charge to backup mode

-Programmable ±2% precision charge input current limit from 125mA to 2A

-±1% backup voltage accuracy

-Automatic backup capacitor balancing

-1.2MHz fixed frequency switching

-Burst Mode® operation: 40μA IQ

-Additional programmable general-purpose comparator with open-collector output

-Open-collector output indicating commands for operation & charge completion

-Low-profile TSSOP-24 & 4mm × 4mm QFN-24 package

USA list price information is for general budget planning purposes, and international prices may vary depending on regional tariffs, taxes, fees, and exchange rates.