SLUS900F December   2008  – August 2026 BQ32000

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     Pin Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings #GUID-4430518C-46E5-4467-8224-12E6F82A6B20/AMR001
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 I2C Timing Requirements
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 IRQ Function
      2. 6.3.2 VBACK Switchover
      3. 6.3.3 Trickle Charge
    4. 6.4 Device Functional Modes
    5. 6.5 Programming
      1. 6.5.1 I2C Serial Interface
  8. 7 Register Maps
    1. 7.1 I2C Read After Backup Mode
    2. 7.2 Normal Register Descriptions
      1. 7.2.1  SECONDS Register (address = 0x00) [reset = 0XXXXXXb]
      2. 7.2.2  MINUTES Register (address = 0x01) [reset = 1XXXXXXb]
      3. 7.2.3  CENT_HOURS Register (address = 0x02) [reset = XXXXXXXXb]
      4. 7.2.4  DAY Register (address = 0x03) [reset = 00000XXXb]
      5. 7.2.5  DATE Register (address = 0x04) [reset = 00XXXXXXb]
      6. 7.2.6  MONTH Register (address = 0x05) [reset = 000XXXXXb]
      7. 7.2.7  YEARS Register (address = 0x06) [reset = XXXXXXXXb]
      8. 7.2.8  CAL_CFG1 Register (address = 0x07) [reset = 10000000b]
      9. 7.2.9  TCH2 Register (address = 0x08) [reset = 10010000b]
      10. 7.2.10 CFG2 Register (address = 0x09) [reset = 10101010b]
    3. 7.3 Special Function Registers
      1. 7.3.1 SF KEY 1 Register (address = 0x20) [reset = 00000000b]
      2. 7.3.2 SF KEY 2 Register (address = 0x21) [reset = 00000000b]
      3. 7.3.3 SFR Register (address = 0x22) [reset = 00000000b]
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Reading From a Register
        2. 8.2.2.2 Leap Year Compensation
        3. 8.2.2.3 Utilizing the Backup Supply
        4. 8.2.2.4 Calibration Example of Crystal Input
        5. 8.2.2.5 Calculating the Super Capacitor Values Example
      3. 8.2.3 Application Curves
    3.     Power Supply Recommendations
    4. 8.3 Layout
      1. 8.3.1 Layout Guidelines
      2. 8.3.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
    2. 9.2 Community Resources
    3. 9.3 Trademarks
  11. 10Revision History
  12.   Mechanical, Packaging, and Orderable Information

6.3.3 Trickle Charge

The BQ32000 includes a trickle charge circuit to maintain the charge of the backup supply when a super capacitor is used. The trickle charge circuit is implemented as a series of three switches that are independently controlled by setting the TCHE[3:0], TCH2, and TCFE bits in the register space.

TCHE[3:0] must be written as 0x5h and TCH2 as 1 to close the trickle charge switches and enable charging of the backup supply from VCC. Additionally, TCFE can be set to 1 to bypass the internal diode and boost the charge voltage of the backup supply. All trickle charge switches are opened when the device is initially powered on and each time the device switches from the main supply to the backup supply. The trickle charge circuit is intended for use with super capacitors; however, BQ32000 can be used with a rechargeable battery under certain conditions. Care must be taken not to overcharge a rechargeable battery when enabling trickle charge. Follow all charging guidelines specific to the rechargeable battery or super capacitor when enabling trickle charge.

bq32000 Trickle Charge Switch Functional DiagramFigure 6-3 Trickle Charge Switch Functional Diagram