Renesas Electronics ISL81601 and ISL81401 bidirectional buck-boost controllers

Renesas Electronics has announced a family of bidirectional four-switch synchronous buck-boost controllers. The ISL81601 and ISL81401 are true bidirectional controllers that sense peak current at both ends and provide cycle-by-cycle current limit in both directions while in buck or boost mode. The controllers generate point-of-load (POL) and voltage rail conversions with peak efficiency up to 99%.

The ISL81601 has a wide input range of 4.5 to 60 V and produces a 0.8 to 60 V output to support most industrial batteries: 12, 24, 36 and 48 V. Also available is the ISL81401, a 4.5 to 40 V input and 0.8 to 40 V output version, and its unidirectional counterpart, the ISL81401A. The controllers are suited to DC power backup and battery-powered medical, industrial and telecommunication systems.

The controllers’ bidirectional peak current sensing capability eliminates complex external circuitry required for charging and discharging a battery to supply power to the loads. Their proprietary algorithm provides smooth mode transitions between buck, boost and buck-boost, while reducing low frequency ripple at Vout, ensuring minimal disturbances during line or load transients. The algorithm also ensures predictable ripple voltage under all conditions.

The addition of multilayer overcurrent protection and a precision control algorithm delivers constant current down to 0.1 V at Vout for ongoing operation. Designers can expand system power by paralleling an unlimited number of controllers. The controllers operate two switches at a time to minimise power loss and achieve higher efficiency.