SLUSBC1B September   2013  – December 2016

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Device Power Up
        1. 8.3.1.1 Power-On-Reset (POR)
        2. 8.3.1.2 Power Up from Battery without DC Source
          1. 8.3.1.2.1 BATFET Turn Off
          2. 8.3.1.2.2 Shipping Mode
        3. 8.3.1.3 Boost Mode Operation from Battery
          1. 8.3.1.3.1 Integrated Control to Switch Between USB Charge Mode and Boost Mode
        4. 8.3.1.4 Power Up from DC Source
          1. 8.3.1.4.1 REGN LDO
          2. 8.3.1.4.2 Input Source Qualification
          3. 8.3.1.4.3 Input Current Limit Detection
          4. 8.3.1.4.4 D+/D- Detection Sets Input Current Limit
          5. 8.3.1.4.5 Force Input Current Limit Detection
        5. 8.3.1.5 Converter Power-Up
        6. 8.3.1.6 Low Power HIZ State
      2. 8.3.2 Power Path Management
        1. 8.3.2.1 Narrow VDC Architecture
        2. 8.3.2.2 Dynamic Power Management
        3. 8.3.2.3 Supplement Mode
      3. 8.3.3 Battery Charging Management
        1. 8.3.3.1 Autonomous Charging Cycle
        2. 8.3.3.2 Battery Charging Profile
        3. 8.3.3.3 Thermistor Qualification
          1. 8.3.3.3.1 Cold/Hot Temperature Window
        4. 8.3.3.4 Charging Termination
          1. 8.3.3.4.1 Termination When REG02[0] = 1
        5. 8.3.3.5 Charging Safety Timer
          1. 8.3.3.5.1 Safety Timer Configuration Change
      4. 8.3.4 Status Outputs (STAT, and INT)
        1. 8.3.4.1 Charging Status Indicator (STAT)
        2. 8.3.4.2 Interrupt to Host (INT)
      5. 8.3.5 Protections
        1. 8.3.5.1 Input Current Limit on ILIM
        2. 8.3.5.2 Thermal Regulation and Thermal Shutdown
        3. 8.3.5.3 Voltage and Current Monitoring in Buck Mode
          1. 8.3.5.3.1 Input Over-Voltage (ACOV)
          2. 8.3.5.3.2 System Over-Voltage Protection (SYSOVP)
        4. 8.3.5.4 Current Monitoring in Boost Mode
        5. 8.3.5.5 Battery Protection
          1. 8.3.5.5.1 Battery Over-Voltage Protection (BATOVP)
          2. 8.3.5.5.2 Battery Short Protection
          3. 8.3.5.5.3 System Over-Current Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Host Mode and Default Mode
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1 Data Validity
        2. 8.5.1.2 START and STOP Conditions
        3. 8.5.1.3 Byte Format
        4. 8.5.1.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 8.5.1.5 Slave Address and Data Direction Bit
          1. 8.5.1.5.1 Single Read and Write
          2. 8.5.1.5.2 Multi-Read and Multi-Write
    6. 8.6 Register Map
      1. 8.6.1 I2C Registers
        1. 8.6.1.1  Input Source Control Register REG00 [reset = 01011000, or 0x58]58 to 0x58 in heading
        2. 8.6.1.2  Power-On Configuration Register REG01 [reset = 0011101100011011 to 00111011 and 0x1B to 0x3B in heading, or 0x3B]
        3. 8.6.1.3  Charge Current Control Register REG02 [reset = 00100000, or 0x20]
        4. 8.6.1.4  Pre-Charge/Termination Current Control Register REG03 [reset = 00010001, or 0x11]
        5. 8.6.1.5  Charge Voltage Control Register REG04 [reset = 10110010, or 0xB2]
        6. 8.6.1.6  Charge Termination/Timer Control Register REG05 [reset = 10011100, or 0x9C]
        7. 8.6.1.7  Boost Voltage/Thermal Regulation Control Register REG06 [reset = 10010011, or 0x93]
        8. 8.6.1.8  Misc Operation Control Register REG07 [reset = 01001011, or 0x4B4B to 0x4B in heading ]
        9. 8.6.1.9  System Status Register REG08
        10. 8.6.1.10 New Fault Register REG09
        11. 8.6.1.11 Vender / Part / Revision Status Register REG0A
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inductor Selection
        2. 9.2.2.2 Input Capacitor
        3. 9.2.2.3 Output Capacitor
      3. 9.2.3 Application Performance Plots
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Application and Implementation

NOTE

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.

9.1 Application Information

A typical application consists of the device configured as an I2C controlled power path management device and a single cell Li-Ion battery charger for single cell Li-Ion and Li-polymer batteries used in a wide range of tablets and other portable devices. It integrates an input reverse-blocking FET (RBFET, Q1), high-side switching FET (HSFET, Q2), low-side switching FET (LSFET, Q3), and BATFET (Q4) between the system and battery. The device also integrates a bootstrap diode for the high-side gate drive.

9.2 Typical Application

bq24295 app_diag_lusbc1.gif Figure 40. bq24295 with USB D+/D- Detection for Charging and Discharging in Boost Mode

9.2.1 Design Requirements

Table 18. Design Requirements

DESIGN PARAMATER EXAMPLE VALUE
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

9.2.2 Detailed Design Procedure

9.2.2.1 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. bq24295 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. bq24295 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.

9.2.2.2 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. bq24295 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.

9.2.2.3 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. bq24295 Eq8_slusaw5.gif

The output capacitor voltage ripple can be calculated as follows:

Equation 8. bq24295 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.

9.2.3 Application Performance Plots

bq24295 scope_2_lusbc1.gif
VBAT = 3.2 V
Figure 41. Power Up with Charge Enabled
bq24295 scope_4_lusbc1.gif
VBAT = 5 V
Figure 43. Charge Enable
bq24295 scope_6_lusbc1.gif
VBUS = 5 V, No Battery, ISYS = 40 mA, Charge Disable
Figure 45. PWM Switching in Buck Mode
bq24295 scope_8_lusbc1.gif
VBUS = 5 V, IIN = 3 A, No Battery, Charge Disable
Figure 47. Input Current DPM Response without Battery
bq24295 scope_10_lusbc1.gif
VBAT = 3.8 V, ILOAD = 1 A
Figure 49. Boost Mode Switching
bq24295 scope_3_lusbc1.gif
VBAT = 3.2 V
Figure 42. Power Up with Charge Disabled
bq24295 scope_5_lusbc1.gif
Figure 44. Charge Disable
bq24295 scope_7_lusbc1.gif
VBUS = 5 V, VBAT = 3.6 V, ICHG = 2.5 A
Figure 46. PFM Switching in Buck Mode
bq24295 scope_9_lusbc1.gif
VBUS = 5 V, IIN = 1.5 A, VBAT = 3.8 V
Figure 48. Load Transient During Supplement Mode
bq24295 scope_11_lusbc1.gif
VBAT = 3.8 V
Figure 50. Boost Mode Load Transient