SLUSDA7A April   2018  – January 2021 BQ25121A

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Ship Mode
        1. 9.3.1.1 Ship Mode Entry and Exit
      2. 9.3.2  High Impedance Mode
      3. 9.3.3  Active Battery Only Connected
      4. 9.3.4  Voltage Based Battery Monitor
      5. 9.3.5  Sleep Mode
      6. 9.3.6  Input Voltage Based Dynamic Power Management (VIN(DPM))
      7. 9.3.7  Input Overvoltage Protection and Undervoltage Status Indication
      8. 9.3.8  Battery Charging Process and Charge Profile
      9. 9.3.9  Dynamic Power Path Management Mode
      10. 9.3.10 Battery Supplement Mode
      11. 9.3.11 Default Mode
      12. 9.3.12 Termination and Pre-Charge Current Programming by External Components (IPRETERM)
      13. 9.3.13 Input Current Limit Programming by External Components (ILIM)
      14. 9.3.14 Charge Current Programming by External Components (ISET)
      15. 9.3.15 Safety Timer
      16. 9.3.16 External NTC Monitoring (TS)
      17. 9.3.17 Thermal Protection
      18. 9.3.18 Typical Application Power Dissipation
      19. 9.3.19 Status Indicators ( PG and INT)
      20. 9.3.20 Chip Disable ( CD)
      21. 9.3.21 Buck (PWM) Output
      22. 9.3.22 Load Switch / LDO Output and Control
      23. 9.3.23 Manual Reset Timer and Reset Output ( MR and RESET)
    4. 9.4 Device Functional Modes
    5. 9.5 Programming
      1. 9.5.1 Serial Interface Description
      2. 9.5.2 F/S Mode Protocol
    6. 9.6 Register Maps
      1. 9.6.1  Status and Ship Mode Control Register
      2. 9.6.2  Faults and Faults Mask Register
      3. 9.6.3  TS Control and Faults Masks Register
      4. 9.6.4  Fast Charge Control Register
      5. 9.6.5  Termination/Pre-Charge Register
      6. 9.6.6  Battery Voltage Control Register
      7. 9.6.7  SYS VOUT Control Register
      8. 9.6.8  Load Switch and LDO Control Register
      9. 9.6.9  Push-button Control Register
      10. 9.6.10 ILIM and Battery UVLO Control Register
      11. 9.6.11 Voltage Based Battery Monitor Register
      12. 9.6.12 VIN_DPM and Timers Register
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Default Settings
        2. 10.2.2.2 Choose the Correct Inductance and Capacitance
        3. 10.2.2.3 Calculations
          1. 10.2.2.3.1 Program the Fast Charge Current (ISET)
          2. 10.2.2.3.2 Program the Input Current Limit (ILIM)
          3. 10.2.2.3.3 Program the Pre-charge/termination Threshold (IPRETERM)
          4. 10.2.2.3.4 TS Resistors (TS)
      3. 10.2.3 Application Performance Curves
        1. 10.2.3.1 Charger Curves
        2. 10.2.3.2 SYS Output Curves
        3. 10.2.3.3 Load Switch and LDO Curves
        4. 10.2.3.4 LS/LDO Output Curves
        5. 10.2.3.5 Timing Waveforms Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Trademarks
    4. 13.4 Support Resources
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.3.22 Load Switch / LDO Output and Control

The device integrates a low Iq load switch which can also be used as a regulated output. The LSCTRL pin can be used to turn the load on or off. Activating LSCTRL continuously holds the switch in the on state so long as there is not a fault. The signal is active HI and has a low threshold making it capable of interfacing with low voltage signals. To limit voltage drop or voltage transients, a small ceramic capacitor must be placed close to VINLS. Due to the body diode of the PMOS switch, it is recommended to have the capacitor on VINLS ten times larger than the output capacitor on LS/LDO.

The output voltage is programmable using the LS_LDO bits in the register. The LS/LDO voltage is calculated using Equation 9.

Equation 9. LS/LDO = 0.8 V + LS_LDOCODE x 100 mV

If a value greater than 3.3 V is written, the setting goes to pass-through mode where LS/LDO = VINLS - V(DROPOUT). Table 9-9 summarizes the control of the LS/LDO output based on the I2C or LSCTRL pin setting:

Table 9-9 LS/LDO Output Control
I2C LS_LDO_ENPIN LSCTRLI2C VLDO > 3.3LS/LDO OUTPUT
000Pulldown
001Pulldown
010VLDO
011LSW
100VLDO
101LSW
110VLDO
111LSW

If the output of the LDO is less than the programmed V(SYS) voltage, connect VINLS to SYS. If the output of the LDO is greater than the programmed VSYS voltage, connect VINLS to PMID.

The current capability of the LDO depends on the VINLS input voltage and the programmed output voltage. The full 100-mA output current for 0.8-V output voltage can be achieved when V(VINLS) > 3.25 V. The full 100-mA output current for 3.3-V output voltage can be achieved when V(VINLS) > 3.6 V.

When the LSLDO output is disabled with LSCTRL or through the register, an internal pull-down discharges the output.