BQ24721C Smart Battery Charger with SMBus and System Power Selector, Softer Turn-On |

BQ24721C (NRND) Smart Battery Charger with SMBus and System Power Selector, Softer Turn-On



The bq24721 is a high efficiency synchronous battery pack charger with high level of integration for portable applications. This device implements a high performance analog front-end that interfaces to the system power management micro-controller through a simplified SBS-like SMBus interface.

The dynamic power management (DPM) function modifies the charge current depending on system load conditions, avoiding ac adapter overload.

High accuracy current sense amplifiers enable accurate measurement of either the charge current or the ac adapter current, allowing termination of nonsmart packs and monitoring of overall system power.

The adapter isolation diode can be bypassed or entirely replaced with an external MOSFET using a control signal provided by the bq24721, thus reducing overall power dissipation.

Integrated features such as charger soft start, charge overcurrent protection, and IC temperature monitoring provide a second level of protection, in addition to pack and system protection functions.


  • High Efficiency NMOS-NMOS Synchronous Buck Converter With User-Selectable 300 kHz or 500 kHz frequency
  • bq24721C Offers Softer Turn-On, Stronger Turn-Off
  • SBS-Like(1) SMBus Interface for Control and Status Communications With Host
  • Programmable Battery Voltage, Charge Current, and AC Adapter Current via SBS-Like SMBus Interface
  • 0.4% Charge Voltage Regulation Accuracy
  • 3% Charge Current Regulation Accuracy
  • 3% Adapter Current Regulation Accuracy Dynamic Power Management (DPM)
  • 2% Accuracy Integrated Charge and AC Adapter 20× Current Amplifier Output
  • 3-Cell and 4-Cell Li-Ion Voltage Regulation 9 V, 12 V-14.4 V, 16 V-19.2 V
  • Battery Pack Voltage Operating Range 0 V-19.2 V
  • AC Adapter Operating Range 8 V-28 V
  • 99.5% Max Duty Cycle
  • Internal Soft Start
  • Integrated 5% 5-V LDO When AC Adapter Applied
  • 6-V Drive Supply Voltage for Increased Efficiency
  • Reverse Battery to Adapter Discharge Protection
  • Battery/Adapter to System Power Selector Function
  • Charge and Adapter Overcurrent Protection
  • Battery Thermistor Sense, TS, Comparators
  • Available in 32-Pin 5x5-mm QFN Package
    • Portable Notebook Computers
    • Portable DVD Players
    • Webpads, PC Tablets

(1) SBS-Like interface is not 100% SBS compliant. SBS-Like interface is SMBus1.1 complaint but does not support Packet Error Correction (PEC). The control and status registers were changed to simplify and enhance notebook charger control. An 8-bit address (0x12) is used.
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