The TPS63805 and TPS63806 buck-boost converter use four internal switches to maintain synchronous power conversion at all possible operating conditions. This enables the device to keep high efficiency over a wide input voltage and output load range. To regulate the output voltage at all possible input voltage conditions, the device automatically transitions between buck, buck-boost, and boost operation as required by the operating conditions. Therefore, it operates as a buck converter when the input voltage is higher than the output voltage, and as a boost converter when the input voltage is lower than the output voltage. When the input voltage is close to the output voltage, it operates in a 3-cycle buck-boost operation. In this mode, all four switches are active (see Buck-Boost Operation). The RMS current through the switches and the inductor is kept at a minimum to minimize switching and conduction losses. Controlling the switches this way allows the converter to always keep high efficiency over the complete input voltage range. The device provides a seamless transition between all modes.