SLUSBH2E March 2013  – March 2015


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1Absolute Maximum Ratings
    2. 6.2ESD Ratings
    3. 6.3Recommended Operating Conditions
    4. 6.4Thermal Information
    5. 6.5Electrical Characteristics
    6. 6.6Electrical Characteristics
    7. 6.7Typical Characteristics
  7. Detailed Description
    1. 7.1Overview
    2. 7.2Functional Block Diagram
    3. 7.3Feature Description
      1. 7.3.1Maximum Power Point Tracking
      2. 7.3.2Battery Undervoltage Protection
      3. 7.3.3Battery Overvoltage Protection
      4. 7.3.4Battery Voltage within Operating Range (VBAT_OK Output)
      5. 7.3.5Storage Element / Battery Management
      6. 7.3.6Programming OUT Regulation Voltage
      7. 7.3.7Step Down (Buck) Converter
      8. 7.3.8Nano-Power Management and Efficiency
    4. 7.4Device Functional Modes
      1. 7.4.1Main Boost Charger Disabled (Ship Mode) - (VSTOR > VSTOR_CHGEN and EN = HIGH)
      2. 7.4.2Cold-Start Operation (VSTOR < VSTOR_CHGEN, VIN_DC > VIN(CS) and PIN > PIN(CS), EN = don't care)
      3. 7.4.3Main Boost Charger Enabled (VSTOR > VSTOR_CHGEN and EN = LOW )
        1. Converter Enabled (VSTOR > VBAT_UV, EN = LOW and VOUT_EN = HIGH )
      4. 7.4.4Thermal Shutdown
  8. Application and Implementation
    1. 8.1Application Information
      1. 8.1.1Energy Harvester Selection
      2. 8.1.2Storage Element Selection
      3. 8.1.3Inductor Selection
        1. Charger Inductor Selection
        2. Converter Inductor Selection
      4. 8.1.4Capacitor Selection
        1. Capacitance
        2. Capacitance
        3. Capacitance
        4. Capacitance
        5. Capacitance on VSTOR or VBAT
    2. 8.2Typical Applications
      1. 8.2.1Solar Application Circuit
        1. Requirements
        2. Design Procedure
        3. Curves
      2. 8.2.2TEG Application Circuit
        1. Requirements
        2. Design Procedure
        3. Curves
      3. 8.2.3Piezoelectric Application Circuit
        1. Requirements
        2. Design Procedure
        3. Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1Layout Guidelines
    2. 10.2Layout Example
    3. 10.3Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1Device Support
      1. 11.1.1Third-Party Products Disclaimer
    2. 11.2Documentation Support
      1. 11.2.1Related Documentation
    3. 11.3Trademarks
    4. 11.4Electrostatic Discharge Caution
    5. 11.5Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Orderable Information

1 Features

  • Ultra Low Power DC-DC Boost Charger
    • Cold-start Voltage: VIN ≥ 330 mV
    • Continuous Energy Harvesting From VIN as low as 100 mV
    • Input Voltage Regulation Prevents Collapsing High Impedance Input Sources
    • Full Operating Quiescent Current of 488 nA (typical)
    • Ship Mode with < 5 nA From Battery
  • Energy Storage
    • Energy can be Stored to Re-chargeable Li-ion Batteries, Thin-film Batteries, Super-capacitors, or Conventional Capacitors
  • Battery Charging and Protection
    • Internally Set Undervoltage Level
    • User Programmable Overvoltage Levels
  • Battery Good Output Flag
    • Programmable Threshold and Hysteresis
    • Warn Attached Microcontrollers of Pending Loss of Power
    • Can be Used to Enable or Disable System Loads
  • Programmable Step Down Regulated Output (Buck)
    • High Efficiency up to 93%
    • Supports Peak Output Current up to 110 mA (typical)
  • Programmable Maximum Power Point Tracking (MPPT)
    • Provides Optimal Energy Extraction From a Variety of Energy Harvesters including Solar Panels, Thermal and Piezo Electric Generators

2 Applications

  • Energy Harvesting
  • Solar Chargers
  • Thermal Electric Generator (TEG) Harvesting
  • Wireless Sensor Networks (WSN)
  • Low Power Wireless Monitoring
  • Environmental Monitoring
  • Bridge and Structural Health Monitoring (SHM)
  • Smart Building Controls
  • Portable and Wearable Health Devices
  • Entertainment System Remote Controls

3 Description

The bq25570 device is specifically designed to efficiently extract microwatts (µW) to milliwatts (mW) of power generated from a variety of high output impedance DC sources like photovoltaic (solar) or thermal electric generators (TEG) without collapsing those sources. The battery management features ensure that a rechargeable battery is not overcharged by this extracted power, with voltage boosted, or depleted beyond safe limits by a system load. In addition to the highly efficient boosting charger, the bq25570 integrates a highly efficient, nano- power buck converter for providing a second power rail to systems such as wireless sensor networks (WSN) which have stringent power and operational demands. All the capabilities of bq25570 are packed into a small foot-print 20-lead 3.5-mm x 3.5-mm QFN package (RGR).

Device Information(1)

bq25570VQFN (20)3.50 mm × 3.50 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Typical Application Schematic

bq25570 app1_lusbh2.gif

Charger Efficiency vs Input Voltage

bq25570 C002_SLUSBH2.png