SLUSAL0C September   2011  – January 2020 BQ24725A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 SMBus Interface
    4. 8.4 Device Functional Modes
      1. 8.4.1  Adapter Detect and ACOK Output
      2. 8.4.2  Adapter Over Voltage (ACOVP)
      3. 8.4.3  System Power Selection
      4. 8.4.4  Battery LEARN Cycle
      5. 8.4.5  Enable and Disable Charging
      6. 8.4.6  Automatic Internal Soft-Start Charger Current
      7. 8.4.7  High Accuracy Current Sense Amplifier
      8. 8.4.8  Charge Timeout
      9. 8.4.9  Converter Operation
      10. 8.4.10 Continuous Conduction Mode (CCM)
      11. 8.4.11 Discontinuous Conduction Mode (DCM)
      12. 8.4.12 Input Over Current Protection (ACOC)
      13. 8.4.13 Charge Over Current Protection (CHGOCP)
      14. 8.4.14 Battery Over Voltage Protection (BATOVP)
      15. 8.4.15 Battery Shorted to Ground (BATLOWV)
      16. 8.4.16 Thermal Shutdown Protection (TSHUT)
      17. 8.4.17 EMI Switching Frequency Adjust
      18. 8.4.18 Inductor Short, MOSFET Short Protection
    5. 8.5 Register Maps
      1. 8.5.1 Battery-Charger Commands
      2. 8.5.2 Setting Charger Options
        1. Table 3. Charge Options Register (0x12H)
      3. 8.5.3 Setting the Charge Current
        1. Table 4. Charge Current Register (0x14H), Using 10mΩ Sense Resistor
      4. 8.5.4 Setting the Charge Voltage
        1. Table 5. Charge Voltage Register (0x15H)
      5. 8.5.5 Setting Input Current
        1. Table 6. Input Current Register (0x3FH), Using 10mΩ Sense Resistor
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical System with Two NMOS Selector
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Negative Output Voltage Protection
          2. 9.2.1.2.2 Reverse Input Voltage Protection
          3. 9.2.1.2.3 Reduce Battery Quiescent Current
          4. 9.2.1.2.4 Inductor Selection
          5. 9.2.1.2.5 Input Capacitor
          6. 9.2.1.2.6 Output Capacitor
          7. 9.2.1.2.7 Power MOSFETs Selection
          8. 9.2.1.2.8 Input Filter Design
          9. 9.2.1.2.9 BQ24725A Design Guideline
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Simplified System without Power Path
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
    3. 9.3 System Examples
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.5.2 Setting Charger Options

By writing ChargeOption() command (0x12H or 0b00010010), BQ24725A allows users to change several charger options after POR (Power On Reset) as shown in Table 3.

Figure 14. Charge Options Register (0x12H)
15 14 13 12 11 10 9 8
ACOK Deglitch Time Adjust WATCHDOG Timer Adjust BAT Depletion Comparator Threshold Adjust EMI Switching Frequency Adjust EMI Switching Frequency Enable IFAULT_HI Comparator Threshold Adjust
R/W R/W R/W R/W R/W R/W R/W
7 6 5 4 3 2 1 0
IFAULT_LOW Comparator Threshold Adjust LEARN Enable IOUT Selection AC Adapter Indication (Read Only) Not in use Not in use ACOC Threshold Adjust Charge Inhibit
R/W R/W R/W R/W R/W R/W R/W R/W
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 3. Charge Options Register (0x12H)

Bit Field Type Reset Description
[15] ACOK Deglitch Time Adjust R/W Adjust ACOK deglitch time.
After POR, the first time the adapter plug in occurs, deglitch time is always 150ms no matter if this bit is 0 or 1. This bit only sets the next ACOK deglitch time after ACFET turns off at least one time. To change this option, VCC pin voltage must be above UVLO and ACDET pin voltage must be above 0.6V to enable IC SMBus communication.
0: ACOK rising edge deglitch time 150ms
1: ACOK rising edge deglitch time 1.3s <default at POR>
[14:13] WATCHDOG Timer Adjust R/W Set maximum delay between consecutive SMBus Write charge voltage or charge current command. The charge will be suspended if IC does not receive write charge voltage or write charge current command within the watchdog time period and watchdog timer is enabled.
The charge will be resumed after receive write charge voltage or write charge current command when watchdog timer expires and charge suspends.
00: Disable Watchdog Timer
01: Enabled, 44 sec
10: Enabled, 88 sec
11: Enable Watchdog Timer (175s) <default at POR>
[12:11] BAT Depletion Comparator Threshold Adjust R/W This is used for LEARN function battery over discharge protection. During LEARN cycle, when the IC detects battery voltage is below depletion voltage threshold, the IC turns off BATFET and turned on ACFET to power the system from AC adapter instead of the battery. The rising edge hysteresis is 340mV. Set ChargeVoltage() register value to 0V will disable this function.
00: Falling Threshold = 59.19% of voltage regulation limit (~2.486V/cell)
01: Falling Threshold = 62.65% of voltage regulation limit (~2.631V/cell)
10: Falling Threshold = 66.55% of voltage regulation limit (~2.795V/cell)
11: Falling Threshold = 70.97% of voltage regulation limit (~2.981V/cell) < default at POR>
[10] EMI Switching Frequency Adjust R/W 0: Reduce PWM switching frequency by 18% <default at POR>
1: Increase PWM switching frequency by 18%
[9] EMI Switching Frequency Enable R/W 0: Disable adjust PWM switching frequency <default at POR>
1: Enable adjust PWM switching frequency
[8] IFAULT_HI Comparator Threshold Adjust R/W Short circuit protection high side MOSFET voltage drop comparator threshold.
0: function is disabled
1: 750mV <default at POR>
[7] IFAULT_LOW Comparator Threshold Adjust R/W Short circuit protection low side MOSFET voltage drop comparator threshold.
0: 135mV <default at POR>
1: 230mV
[6] LEARN Enable R/W Set this bit 1 start battery learn cycle. IC turns off ACFET and turns on BATFET to discharge battery capacity. When battery voltage reaches threshold defined in bit [12;11], the BATFET is turned off and ACFET is turned on to finish battery learn cycle. After finished learn cycle, this bit is automatically reset to 0. Set this bit 0 will stop battery learn cycle. IC turns off BATFET and turns on ACFET.
0: Disable LEARN Cycle <default at POR>
1: Enable LEARN Cycle
[5] IOUT Selection R/W 0: IOUT is the 20x adapter current amplifier output <default at POR>
1: IOUT is the 20x charge current amplifier output
[4] AC Adapter Indication (Read Only) R/W 0: AC adapter is not present (ACDET < 2.4V) <default at POR>
1: AC adapter is present (ACDET > 2.4V)
[3] Not in use R/W 0 at POR
[2] Not in use R/W 0 at POR
[1] ACOC Threshold Adjust R/W 0: function is disabled
1: 3.33x of input current regulation limit <default at POR>
[0] Charge Inhibit R/W 0: Enable Charge <default at POR>
1: Inhibit Charge