ISL81601 is a true bidirectional 4-switch synchronous buck-boost controller for efficient DC-DC power conversion with peak and average current sensing and monitoring at both ends. It provides cycle-by-cycle current limit in both directions while in buck or boost mode, and generates point-of-load (POL) and voltage rail conversions with peak efficiency up to 99%. The controller uses a proprietary buck-boost algorithm that allows inherent peak current sensing for a robust design and produces the smoothest mode transitions between buck, boost and buck-boost. Its proprietary algorithm reduces low frequency ripple at Vout, ensuring minimal disturbances during line or load transients. The algorithm also ensures predictable ripple voltage under all conditions. The ISL81601 features multilayer overcurrent protection (OCP) that helps designers to design a charging/discharging circuit that ensures constant current operation for safe and reliable battery power applications. It is available in 32LD 5mmx5mm QFN and 38LD HTSSOP packages and provides full protection features such OVP, UVP, OTP and OCP. ISL81601 is a 4.5Vin~ 60Vin device and the ISL81401 is a 4.5Vin~40Vin device. The ISL81401A is a low cost unidirectional version of the ISL81401.