SMBus Level 2 Battery Charger

Product Status: Mass Production


The ISL88731 is a highly integrated Lithium-ion battery charger controller, programmable over the SMBus system management bus (SMBus). The ISL88731 is intended to be used in a smart battery charger (SBC) within a smart battery system (SBS) that throttles the charge power such that the current from the AC-adapter is automatically limited. High efficiency is achieved with a DC/DC synchronous-rectifier buck converter, equipped with diode emulation for enhanced light load efficiency and system bus boosting prevention. The ISL88731 charges one to four Lithium-ion series cells, and delivers up to 8A charge current. Integrated MOSFET drivers and bootstrap diode result in fewer components and smaller implementation area. Low offset current-sense amplifiers provide high accuracy with 10mΩ sense resistors. The ISL88731 provides 0.5% end-of-charge battery voltage accuracy.

The ISL88731 provides a digital output that indicates the presence of the AC adapter as well as an analog output which indicates the adapter current within 4% accuracy.

The ISL88731 is available in a small 5mmx5mm 28 Ld Thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The ISL88731 is available in Pb-Free packages.


  • 0.5% Battery Voltage Accuracy
  • 3% Adapter Current Limit Accuracy
  • 3% Charge Current Accuracy
  • SMBus 2-Wire Serial Interface
  • Battery Short Circuit Protection
  • Fast Response for Pulse-Charging
  • Fast System-Load Transient Response
  • Monitor Outputs
  • Adapter Current (3% Accuracy)
  • AC-Adapter Detection
  • 11-Bit Battery Voltage Setting
  • 6 Bit Charge Current/Adapter Current Setting
  • 8A Maximum Battery Charger Current
  • 11A Maximum Adapter Current
  • +8V to +28V Adapter Voltage Range
  • Pb-Free (RoHS Compliant)


 Block Diagram


Basic Information
Production Status
Mass Production
Input Voltage Min (V)
Input Voltage Max (V)
Input Current Limit Accuracy (%)
Battery Charge Voltage (V)
2.7 to 19.2 in 16mV Steps
Charging Voltage Accuracy Max (%)
Battery Charge Voltage Adjust (%)
16mV steps
Charge Current Limit Accuracy (%)
Trickle Charge Current Limit Accuracy (%)
64mA to 220mA
Automatic Trickle Charge Typ (V)
Battery Leakage Current Max (μA)
2 (DCIN=0V, No System Load)
Automatic Power Source Selection
No (Set by Host)
DC Adapter Detection
No (Set by Host)
Fixed Frequency Synchronous Buck
Switching Frequency Typ (kHz)
Max Duty Cycle (%)
Audible Noise
Thermal Shutdown (°C)
150 °C
Battery Chemistry
Multi-Cell Li+/Polymer
Qualification Level
Input Voltage Range (V)
7 to 25
Can Sample
Temperature Range
-10 to +100

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