In today’s modern electronic systems, the need for power conversion circuits that can do more than simply convert one voltage to another is growing. Some systems require a constant current output or a constant voltage output; others may require the current to flow from input to output or output to input. All of these requirements are in addition to the normal requirements of high conversion efficiency and high operating voltage ranges.
Linear Technology’s LT8710 is a synchronous SEPIC/inverting/boost controller IC with three regulation loops, which can operate from an input voltage up to 80V. When configured as a SEPIC or boost converter, the output voltage can be set from 1.3V to 80V. When the LT8710 is used in an inverting converter, the output voltage can be set from -0.1V to -80V. The LT8710 can operate with input voltages above, equal to, or below the desired output voltage when operating as a SEPIC converter. As long as the output voltage is greater than 4.5V, the input voltage can drop down to nearly 0V, and the converter will still operate, which allows for very wide input range applications. The integrated strong gate drivers allow a single LT8710 circuit to process up to 100W of power.
The LT8710 has three regulation loops built in. These loops can be set up to regulate output voltage, output current, and input voltage. Any combination of these loops can be used in a given system. The FLAG pin on the LT8710 is an open-drain pin that operates as a power good and 1/10th charging current detection (C/10) pin. The C/10 functionality is very useful when charging sealed lead acid batteries to set a bulk and float battery voltage. Input voltage regulation can be used to avoid collapsing a high-impedance input supply such as a solar panel. In case the input source is suddenly removed, the LT8710 can command current from output to input, and the input voltage can be held up for some time as set by the input voltage regulation loop, creating a backup power source.