MAX77857 Buck-Boost Converter

ADI's MAX77857 is a high-efficiency, high-performance buck-boost converter for systems requiring a wide input voltage range (2.5 V to 16 V). It features a 7 A switching current and can supply up to 6 A output current in buck mode and up to 4 A in boost mode (boost ratio ≤ 1.3). It operates in PWM mode and implements an automatic skip mode to improve light-load efficiency.

The output voltage is adjustable dynamically throught the I²C serial interface. The default output voltage is 5 V when using internal feedback resistors. It can also be configured to any default output voltages between 3 V and 15 V when using external feedback resistors.

The use of external feedback resistors allows for a wider output voltage range and customizable output voltages at startup. The SEL pin allows a single external resistor to program four I²C interface slave addresses, four switching current limit thresholds, and selection between external or internal feedback resistors. The different switching current limit thresholds allow the use of lower profile and smaller external components optimized for a particular application.

The I²C serial interface is optional and allows for dynamically controlling the output voltage, slew rate of the output voltage change, switching-current limit threshold, switching frequency, and forced PWM mode operation. The I²C-programmed settings have priority over the RSEL decoded settings.

The MAX77857 evaluation kit (EV kit) is a fully assembled and tested printed circuit board (PCB) demonstrating the MAX77857. The EV kit is factory-configured as internal feedback with a default startup output voltage at 5 V. Other startup voltages can be achieved with external feedback resistors. The output voltage can be adjusted dynamically through the I²C serial interface.