FN8937 Rev.1.01 Page 1 of 50

Oct.16.20

ISL81801

80V Bidirectional 4-Switch Synchronous Buck-Boost Controller

Datasheet

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,

and after-market automotive 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 IC is packaged in a space-conscious 32 LD

5mm x5mm TQFN package or easy to assemble

4.4mmx9.7mm 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. The unique

DE/Burst mode at light-load dramatically lowers

standby power consumption with consistent output

ripple over different load levels.

Related Literature

For a full list of related documents, visit our website:

• ISL81801

device page

Features

• 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

Applications

• 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