The ISL81801 is a true bidirectional 4-switch synchronous buck-boost controller with peak and average current sensing and monitoring at both ends. With wide input and output voltage ranges, the controller is suitable for industrial, telecommunication, other industrial applications.

The ISL81801 uses a proprietary buck-boost control algorithm with valley current modulation for Boost mode and peak current modulation for Buck mode control.

The ISL81801 has 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 end 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, average and peak current limit on both input and output to ensure high reliability in both unidirectional and bidirectional operation. The unique DE/Burst mode at light-load dramatically lowers standby power consumption with consistent output ripple over different load levels.

The IC is packaged in a space-conscious 32 LD 5mm × 5mm TQFN package or easy to assemble 4.4mm × 9.7mm 38 LD HTSSOP package. Both packages use an EPAD to improve thermal performance and noise immunity. Low pin count, fewer external components, and default internal values make the ISL81801 an ideal solution for time to market simple power supply designs.


  • Single inductor 4-switch buck-boost controller
  • On-the-fly bidirectional operation with independent control of voltage and current on both ends
  • Proprietary algorithm for smoothest mode transition
  • MOSFET drivers with adaptive shoot-through protection
  • Wide input voltage range: 4.5V to 80V
  • Wide output voltage range: 0.8V to 80V
  • Supports startup into pre-biased rails
  • Programmable frequency: 100kHz to 600kHz
  • Supports parallel operation current sharing with cascade phase interleaving
  • External sync with clock out or frequency dithering
  • External bias for higher efficiency for 8V to 36V input
  • Output and input current monitor
  • Selectable PWM mode operation between PWM/DE/Burst modes
  • Accurate EN/UVLO and PGOOD indicator
  • Low shutdown current: 2.7µA
  • Complete protection: OCP, SCP, OVP, OTP, and UVP
    • Dual-level OCP with average current and pulse-by-pulse peak current limit, also provides Short Circuit Protection (SCP)
    • Selectable OCP response with either hiccup or constant current mode
    • Negative pulse-by-pulse peak current limit


  • Battery backup
  • UPS/storage systems
  • Battery powered industrial applications
  • Renewable energy
  • Aftermarket automotive
  • Redundant power supplies
  • Robots and drones
  • Medical equipment
  • Building and industrial automation
  • Security surveillance


Title language Type Format File Size Date
star ISL81801 Datasheet Datasheet PDF 1.63 MB
ISL81801 Design Tool Other XLSX 2.16 MB
ISL81801 80Vin 5Vout 10A iSim:PE Model Schematic SXSCH 512 KB


select_allSoftware & Tool Pages

Title Type Description Company
iSim:PE Offline Simulation Tool Simulator iSim Personal Edition (iSim:PE) speeds the design cycle and reduces risk early in any project, identifying parts that can be used in current as well as next-generation designs. Renesas

memoryBoards & Kits

Part Number Title Type Company
ISL81801EVAL1Z 80V Bidirectional 4-Switch Synchronous Buck-Boost Controller Evaluation Board Evaluation Renesas
ISL81801EVAL2Z 80V Bidirectional 4-Switch Synchronous Buck-Boost Controller Evaluation Board Evaluation Renesas
ISL81801DEMO1Z 80V Bidirectional 4-Switch Synchronous Buck-Boost Controller Demonstration Board Demonstration Renesas