The ISL81401 and ISL81401A are 4-switch synchronous buck-boost controller with peak and average current sensing and monitoring at both ends. The ISL81401 is a bidirectional device that can conduct current in both directions while the ISL81401A is an unidirectional device. The ISL81401 and ISL81401A use the proprietary buck-boost control algorithm with valley current modulation for Boost mode and peak current modulation for Buck mode control. The ISL81401 and ISL81401A have four independent control loops for input and output voltages and currents. Inherent peak current sensing at both ends and cycle-by-cycle current limit of this family of products ensures high operational reliability by providing instant current limit in fast transient conditions at either ends and in both directions. It also has two current monitoring pins at both input and output to facilitate Constant Current (CC) limit and other system management functions. CC operation down to low voltages avoids any runaway condition at over load or short-circuit conditions. In addition to multilayer overcurrent protection, it also provides full protection features such as OVP, UVP, OTP, and average and peak current limit on both input and output to ensure high reliability in both unidirectional and bidirectional operation. The IC is packaged in a space conscious 32 Ld 5mmx5mm QFN package to improve thermal dissipation and noise immunity. The unique DE/Burst mode at light-load dramatically lowers standby power consumption with consistent output ripple over different load levels.