SLUS900F December   2008  – August 2026

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

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8.2.2.3 Utilizing the Backup Supply

For the BQ32000 to achieve a low backup supply current as specified in the Section 5.5, the VCC pin must be initialized after every total power loss situation. Initialization Is achieved by powering on VCC with a voltage between 3 to 3.6V for at least 1ms immediately after the backup supply is connected. If the VCC is not powered on while connecting the backup supply, then the expected leakage current from VBACK is much greater than specified.

For example after installing the supercap or backup battery, provide VCC to the RTC for at least 1ms, then remove the VCC supply. When VCC is applied to the device, the device automatically switches to use the supply from VCC. After removing the VCC supply, the device switches to use backup supply at the current as specified in the Section 5.5.