SLVSHK6A March   2025  – March 2026 TPS61381-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    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 Characteristics
    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 VCC Power Supply and UVLO Logic
      2. 6.3.2 Enable or Shutdown
      3. 6.3.3 Device Operating Modes and Control Logic
      4. 6.3.4 Status Indicator IO (STATUS Pin)
      5. 6.3.5 Thermal Shutdown
    4. 6.4 Charger Feature Description
      1. 6.4.1 Charger Enable
      2. 6.4.2 LDO Charger
      3. 6.4.3 NiMH Battery Charging Profile
      4. 6.4.4 Lithium Battery Charging Profile
      5. 6.4.5 Super Capacitor Charging Profile
      6. 6.4.6 Battery Cold, Hot Temperature (TS Pin)
      7. 6.4.7 Charger Protection and Fault Condition Indication
    5. 6.5 Boost Feature Description
      1. 6.5.1 Enable and Start up
        1. 6.5.1.1 Automatic Transition into Boost Mode
        2. 6.5.1.2 Manual Transition into Boost Mode
      2. 6.5.2 Down Mode
      3. 6.5.3 Output Short- to-Ground Protection
      4. 6.5.4 Boost Control Loop
      5. 6.5.5 Current Limit Operation
      6. 6.5.6 Functional Modes at Light Load
        1. 6.5.6.1 Auto PFM Mode
        2. 6.5.6.2 Forced PWM Mode
      7. 6.5.7 Duty Cycle Limitation
      8. 6.5.8 BUB Voltage Loop
      9. 6.5.9 Spread Spectrum
    6. 6.6 Battery State-of-Health (SOH) Detection Feature Description
      1. 6.6.1 SOH Mode Operation
      2. 6.6.2 Multi-Signal Output in AVI Pin
      3. 6.6.3 Calculate Impedance of BUB
    7. 6.7 I2C Serial Interface
      1. 6.7.1 Data Validity
      2. 6.7.2 START and STOP Conditions
      3. 6.7.3 Byte Format
      4. 6.7.4 Acknowledge (ACK) and Not Acknowledge (NACK)
      5. 6.7.5 Slave Address and Data Direction Bit
      6. 6.7.6 Single Read and Write
      7. 6.7.7 Multi-Read and Multi-Write
  8. 7 Register Maps
    1. 7.1  Register 00H: CHIP_ID
    2. 7.2  Register 01H: BOOST_SET1
    3. 7.3  Register 02H: BOOST_SET2
    4. 7.4  Register 03H: BOOST_SET3
    5. 7.5  Register 04H: CHGR_SET1
    6. 7.6  Register 05H: CHGR_SET2
    7. 7.7  Register 06H: CHGR_SET3
    8. 7.8  Register 07H: CHGR_SET4
    9. 7.9  Register 08H: CHGR_STATUS
    10. 7.10 Register 09H: SOH_SET1
    11. 7.11 Register 0AH: SOH_SET2
    12. 7.12 Register 0BH: CONTROL_STATUS
    13. 7.13 Register 0CH: FAULT_CONDITION
    14. 7.14 Register 0DH: STATUS_PIN_SET
    15. 7.15 Register 0EH: SW_RST
  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 Selecting the External MOSFET
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Capacitor in Back-Up Battery Side
        4. 8.2.2.4 Selecting the Output Capacitor
        5. 8.2.2.5 Loop Stability and Compensation Design
          1. 8.2.2.5.1 Small Signal Analysis
          2. 8.2.2.5.2 Loop Compensation Design
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

6.4.3 NiMH Battery Charging Profile

In NiMH charging mode, TPS61381-Q1 charges batteries with a time-controlled charging profile consisting of two phases: continuous charge and intermittent charge (optional).

Before initiating a NiMH charging cycle, the device checks the battery status. If back up battery voltage (VBUB) is above 1.34V*cell number (Set by I2C bit BUB_CELL, Register 05H: CHGR_SET2), the device consider back up battery as fully charged. The device does not start charging and I2C CHGR_MODE_DONE bit (Register 08H: CHGR_STATUS) sets 1 to indicate that the charging cycle is done.

If the initial back up battery voltage is below 1.34V×cell number, TPS61381-Q1 enters continuous charge phase. The backup battery is charged with constant current controlled by a pre-set timer. Charging current and the duration for continuous charging phase can be programmed by I2C interface (Register 04H to 05H: BUB_CC, BUB_NIMH_TIMER). After timer is done and the continuous charge phase finishes, TPS61381-Q1 sets I2C bit CHGR_MODE_DONE bit (Register 08H: CHGR_STATUS) to 1 to indicate the charging cycle is done.

If the re-charge function is disabled (Set by I2C bit BUB_TER, Register 06H: CHGR_SET3), the IC stops charging after continuous charging phase is finished. User can restart charging by toggling the EN_CHGR pin or I2C CHGR_EN bit, this clears the CHGR_MODE_DONE bit and restart the continuous charge phase.

TPS61381-Q1 NiMH Battery Charging Profile, Re-Charge Disabled Figure 6-5 NiMH Battery Charging Profile, Re-Charge Disabled

If the re-charge is enabled (Set by I2C bit BUB_TER, Register 06H: CHGR_SET3), the device enters intermittent charging phase after continuous charging phase is finished. In this phase, the IC replenishes the natural self-discharge of NiMH by charging the battery intermittently with pulse charge cycle (2s on and 58s off).

TPS61381-Q1 NiMH Battery Charging Profile, Re-Charge Enabled Figure 6-6 NiMH Battery Charging Profile, Re-Charge Enabled

TPS61381-Q1 monitors the battery voltage during all charging phases, if the battery voltage is above 1.70V×cell number, the device stops charging and set I2C bit BUB_OVP (Register 0CH: FAULT_CONDITION) to 1 to indicate a overvoltage protection.