SLUSBP6C September   2013  – December 2016


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (Continued)
  6. Device Comparison Table
  7. Pin Configuration and Functions
  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. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Device Power Up
        1. Power-On-Reset (POR)
        2. Power Up from Battery without DC Source
          1. BATFET Turn Off
          2. Shipping Mode
        3. Power Up from DC Source
          1. REGN LDO
          2. Input Source Qualification
          3. Input Current Limit Detection
          4. D+/D- Detection Sets Input Current Limit (bq24297)
          5. PSEL/OTG Pins Set Input Current Limit
          6. HIZ State with 100mA USB Host
          7. Force Input Current Limit Detection
        4. Converter Power-Up
        5. Boost Mode Operation from Battery
      2. 9.3.2 Power Path Management
        1. Narrow VDC Architecture
        2. Dynamic Power Management
        3. Supplement Mode
      3. 9.3.3 Battery Charging Management
        1. Autonomous Charging Cycle
        2. Battery Charging Profile
        3. Thermistor Qualification
          1. Cold/Hot Temperature Window
        4. Charging Termination
          1. Termination When REG02[0] = 1
        5. Charging Safety Timer
          1. Safety Timer Configuration Change
        6. USB Timer When Charging from USB100mA Source
      4. 9.3.4 Status Outputs (PG, STAT, and INT)
        1. Power Good Indicator (PG) (bq24296)
        2. Charging Status Indicator (STAT)
        3. Interrupt to Host (INT)
      5. 9.3.5 Protections
        1. Input Current Limit on ILIM
        2. Thermal Regulation and Thermal Shutdown
        3. Voltage and Current Monitoring in Buck Mode
          1. Input Over-Voltage (ACOV)
          2. System Over-Voltage Protection (SYSOVP)
        4. Voltage and Current Monitoring in Boost Mode
          1. Over-Current Protection
          2. VBUS Over-Voltage Protection
        5. Battery Protection
          1. Battery Over-Voltage Protection (BATOVP)
          2. Battery Short Protection
          3. System Over-Current Protection
    4. 9.4 Device Functional Modes
      1. 9.4.1 Host Mode and Default Mode
        1. Plug in USB100mA Source with Good Battery
        2. USB Timer When Charging from USB100mA Source
    5. 9.5 Programming
      1. 9.5.1 Serial Interface
        1. Data Validity
        2. START and STOP Conditions
        3. Byte Format
        4. Acknowledge (ACK) and Not Acknowledge (NACK)
        5. Slave Address and Data Direction Bit
          1. Single Read and Write
          2. Multi-Read and Multi-Write
    6. 9.6 Register Map
      1. 9.6.1 I2C Registers
        1.  Input Source Control Register REG00 [reset = 00110xxx, or 3x]
        2.  Power-On Configuration Register REG01 [reset = 00011011, or 0x1B]
        3.  Charge Current Control Register REG02 [reset = 01100000, or 60]
        4.  Pre-Charge/Termination Current Control Register REG03 [reset = 00010001, or 0x11]
        5.  Charge Voltage Control Register REG04 [reset = 10110010, or 0xB2]
        6.  Charge Termination/Timer Control Register REG05 [reset = 10011010, or 0x9A]
        7.  Boost Voltage/Thermal Regulation Control Register REG06 [reset = 01110011, or 0x73]
        8.  Misc Operation Control Register REG07 [reset = 01001011, or 4B]
        9.  System Status Register REG08
        10. New Fault Register REG09
        11. Vender / Part / Revision Status Register REG0A
  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. Inductor Selection
        2. Input Capacitor
        3. Output Capacitor
      3. 10.2.3 Application Performance Plots
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Related Links
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

Application and Implementation


Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

Application Information

The bq24296 and bq24297 evaluation module (EVM) PWR021 is a complete charger module for evaluating the bq24296 and bq24297. The application curves were taken using the bq24296/297 VM-021. Refer to the Related Links section.

Typical Application

bq24296 bq24297 app_diag_SLUSBP6.gif
VREF is the pull up voltage of I2C communication interface.
Figure 40. bq24296 with PSEL from PHY, Charging from SDP/DCP, and Optional BATFET Enable Interface
bq24296 bq24297 app_diag_297_SLUSBP6.gif
VREF is the pull up voltage of I2C communication interface.
Figure 41. bq24297 with USB D+/D- Detection, USB On-The-Go (OTG) and Optional BATFET Enable Interface

Design Requirements

Table 19. Design Requirements

Input voltage range 3.9 V to 6.2 V
Input current limit 3000 mA
Fast charge current 3000 mA
Boost mode output current 1.5 A

Detailed Design Procedure

Inductor Selection

The device has 1.5-MHz switching frequency to allow the use of small inductor and capacitor values. The Inductor saturation current should be higher than the charging current (ICHG) plus half the ripple current (IRIPPLE):

Equation 4. bq24296 bq24297 Eq5_slusaw5.gif

The inductor ripple current depends on input voltage (VBUS), duty cycle (D = VBAT/VVBUS), switching frequency (fs) and inductance (L):

Equation 5. bq24296 bq24297 Eq6_slusaw5.gif

The maximum inductor ripple current happens with D = 0.5 or close to 0.5. Usually inductor ripple is designed in the range of (20 – 40%) maximum charging current as a trade-off between inductor size and efficiency for a practical design.

Input Capacitor

Input capacitor should have enough ripple current rating to absorb input switching ripple current. The worst case RMS ripple current is half of the charging current when duty cycle is 0.5. If the converter does not operate at 50% duty cycle, then the worst case capacitor RMS current ICIN occurs where the duty cycle is closest to 50% and can be estimated by the following equation:

Equation 6. bq24296 bq24297 Eq7_slusaw5.gif

For best performance, VBUS should be decouple to PGND with 1-μF capacitance. The remaining input capacitor should be place on PMID.

Low ESR ceramic capacitor such as X7R or X5R is preferred for input decoupling capacitor and should be placed to the drain of the high side MOSFET and source of the low side MOSFET as close as possible. Voltage rating of the capacitor must be higher than normal input voltage level. 25-V rating or higher capacitor is preferred for 15-V input voltage. 22-μF capacitance is suggested for typical of 3-A to 4-A charging current.

Output Capacitor

Output capacitor also should have enough ripple current rating to absorb output switching ripple current. The output capacitor RMS current ICOUT is given:

Equation 7. bq24296 bq24297 Eq8_slusaw5.gif

The output capacitor voltage ripple can be calculated as follows:

Equation 8. bq24296 bq24297 Eq9_slusaw5.gif

At certain input/output voltage and switching frequency, the voltage ripple can be reduced by increasing the output filter LC.

The charger device has internal loop compensator. To get good loop stability, the resonant frequency of the output inductor and output capacitor should be designed between 15 kHz and 36 kHz. The preferred ceramic capacitor is 6 V or higher rating, X7R or X5R.

Application Performance Plots

bq24296 bq24297 scope_1_lusbc1.gif
VBAT = 3.2 V
Figure 42. bq24296 Power Up with Charge Enabled
bq24296 bq24297 scope_3_lusbc1.gif
VBAT = 3.2 V
Figure 44. bq24297 Power Up with Charge Disabled
bq24296 bq24297 scope_5_lusbc1.gif
Figure 46. Charge Disable
bq24296 bq24297 scope_7_lusbc1.gif
VBUS = 5 V, VBAT = 3.6 V, ICHG = 2.5 A
Figure 48. PFM Switching in Buck Mode
bq24296 bq24297 scope_9_lusbc1.gif
VBUS = 5 V, IIN = 1.5 A, VBAT = 3.8 V
Figure 50. Load Transient During Supplement Mode
bq24296 bq24297 scope_11_lusbc1.gif
VBAT = 3.8 V
Figure 52. Boost Mode Load Transient
bq24296 bq24297 scope_2_lusbc1.gif
VBAT = 3.2 V
Figure 43. bq24297 Power Up with Charge Enabled
bq24296 bq24297 scope_4_lusbc1.gif
VBAT = 5 V
Figure 45. Charge Enable
bq24296 bq24297 scope_6_lusbc1.gif
VBUS = 5 V, No Battery, ISYS = 40 mA, Charge Disable
Figure 47. PWM Switching in Buck Mode
bq24296 bq24297 scope_8_lusbc1.gif
VBUS = 5 V, IIN = 3 A, No Battery, Charge Disable
Figure 49. Input Current DPM Response without Battery
bq24296 bq24297 scope_10_lusbc1.gif
VBAT = 3.8 V, ILOAD = 1 A
Figure 51. Boost Mode Switching