(ACTIVE) NVDC I2C Battery Buck-Boost Charge Controller with System Power Monitor & Processor


Functional diagram


The bq25703A is a synchronous NVDC battery buck-boost charge controller, offering low component count, high efficiency solution for space-constraint, multi-chemistry battery charging applications.

The NVDC-1 configuration allows the system to be regulated at battery voltage, but not drop below system minimum voltage. The system keeps operating even when the battery is completely discharged or removed. When load power exceeds input source rating, the battery goes into supplement mode and prevents the input source from being overloaded.

The bq25703A charges battery from a wide range of input sources including USB adapter, high voltage USB PD sources and traditional adapters.

During power up, the charger sets converter to buck, boost or buck-boost configuration based on input source and battery conditions. The charger automatically transits among buck, boost and buck-boost configuration without host control.

In the absence of an input source, the bq25703A supports On-the-Go (OTG) function from 1- to 4-cell battery to generate 4.48 V to 20.8 V on VBUS. During OTG mode, the charger regulates output voltage and output current.

The bq25703A monitors adapter current, battery current and system power. The flexibly programmed PROCHOT output goes directly to CPU for throttle back when needed.


  • Charge 1- to 4-Cell Battery From Wide Range of Input Sources
    • 3.5-V to 24-V Input Operating Voltage
    • Supports USB2.0, USB 3.0, USB 3.1 (Type C), and USB_PD Input Current Settings
    • Seamless Transition Between Buck and Boost Operation
    • Input Current and Voltage Regulation (IDPM and VDPM) Against Source Overload
  • Power/Current Monitor for CPU Throttling
    • Comprehensive PROCHOT Profile, IMVP8 Compliant
    • Input and Battery Current Monitor
    • System Power Monitor, IMVP8 Compliant
  • Narrow-VDC (NVDC) Power Path Management
    • Instant-On With No Battery or Deeply Discharged Battery
    • Battery Supplements System When Adapter is Fully-Loaded
    • Ideal Diode Operation in Supplement Mode
  • Power Up USB Port From Battery (USB OTG)
    • Output 4.48-V to 20.8-V Compatible With USB PD
    • Output Current Limit up to 6.35 A
  • 800-kHz or 1.2-MHz Programmable Switching Frequency for 1-µH to 2.2-µH Low Profile Inductor
  • Host Control Interface for Flexible System Configuration
    • I2C (bq25703A) Port for Optimal System Performance and Status Reporting
    • Hardware Pin to Set Input Current Limit Without EC Control
  • High Accuracy Regulation and Monitor
    • ±0.5% Charge Voltage Regulation
    • ±2% Input/Charge Current Regulation
    • ±2% Input/Charge Current Monitor
    • ±5% Power Monitor
  • Safety
    • Thermal Shutdown
    • Input, System, Battery Overvoltage Protection
    • MOSFET Inductor Overcurrent Protection
  • Low Battery Quiescent Current
  • Input Current Optimizer (ICO) to Extract Max Input Power
  • Charge Any Battery Chemistry: Li+, LiFePO4, NiCd, NiMH, Lead Acid
  • Package: 32-Pin 4 × 4 WQFN

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Number of Series Cells 1^2^3^4   
Function Charger   
Cell Chemistry Lead Acid^Li-Ion/Li-Polymer^LiFePO4^Lithium phosphate^NiCd^NiMH^SuperCap   
Battery Charge Voltage (Min) (V) 1.024   
Battery Charge Voltage (Max) (V) 19.2   
Features 1-4 Cells^Integrated ADC^USB OTG^Over Voltage Protection^Power Path^Solar Input^Standard BAT Temp Monitoring^Thermal Regulation^Under Voltage Protection^Vin DPM (OK for Solar Power Source)   
Charge Current (Max) (A) 8.128   
Control Interface I2C   
Control Topology Switch-Mode Buck-boost   
Rating Catalog   
Operating Temperature Range (C) -40 to 85   
Pin/Package 32QFN   
Operating Vin (Min) (V) 3.5   
Operating Vin (Max) (V) 24   
Absolute Vin (safety rating) (Max) ((V)) 30   

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