The LTC3127 features a ±4% accurate programmable average input current limit with a 200mA to 1000mA range, making it ideal for GSM modems or Supercapacitor chargers powered from sources with hard limits on output current.
LTC3127 is a 96% efficient, synchronous buck-boost converter with integrated two N-channel MOSFETs and two P-channel MOSFETs. It regulates output voltage in case the input voltage is above, below or equal to the output. It delivers up to 1A of output current. The LTC3127’s input range of 1.8V to 5.5V and output range of 1.8V to 5.25V is compatible with all types of PC card slots, USB and single-cell Li-Ion or dual/triple-cell alkaline/NiCd/NiMH applications.
Current mode buck-boost topology provides a continuous transfer mode through all operating modes and by that simplifies the design and ensures an excellent performance. LTC1327 utilizes two control loops. The inner current loop is internally compensated and forces the input current to equal the commanded current. The outer voltage loop determines the amount of current required to regulate the output voltage. The outer loop is externally compensated which allows stable operation of LTC3127 as general purpose buck-boost converter with 44uF low ESR output capacitor as well as more than 4400uF for GSM class 8 load or even as 100F supercapacitor charger.
The LTC3127’s switching frequency is 1.35MHz which allows minimizing the size of required external components. For applications requiring the lowest possible noise, the burst mode can be disabled and LTC3127 can be configured to run in forced PWM mode, reducing noise and potential RF interference.
When the most efficiency is required, burst mode operation allows quiescent current only 35uA. Shutdown current is less than 1uA, further extending battery run time. Other features include thermal overload protection and output disconnect.
The LTC3127EMSE is available in a 12-lead thermally enhanced MSOP package and the LTC3127EDD is available in a 10-lead DFN package.