SLUSBY5G June   2014  – December 2015

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1  High Impedance Mode
      2. 7.4.2  Battery Only Connected
      3. 7.4.3  Input Connected
        1. 7.4.3.1 Input Voltage Protection in Charge Mode
          1. 7.4.3.1.1 Sleep Mode
          2. 7.4.3.1.2 Input Voltage Based Dynamic Power Management (VIN-DPM)
          3. 7.4.3.1.3 Input Overvoltage Protection
        2. 7.4.3.2 Charge Profile
      4. 7.4.4  Battery Charging Process
      5. 7.4.5  Charge Time Optimizer
      6. 7.4.6  Battery Detection
      7. 7.4.7  Battery Overvoltage Protection (BOVP)
      8. 7.4.8  Dynamic Power Path Management
      9. 7.4.9  Battery Discharge FET (BGATE)
      10. 7.4.10 IUSB1, IUSB2, and IUSB3 Input
      11. 7.4.11 Safety Timer in Charge Mode
      12. 7.4.12 LDO Output (DRV)
      13. 7.4.13 External NTC Monitoring (TS)
      14. 7.4.14 Thermal Regulation and Protection
      15. 7.4.15 Status Outputs (CHG, PG)
      16. 7.4.16 Boost Mode Operation
        1. 7.4.16.1 PWM Controller in Boost Mode
        2. 7.4.16.2 Burst Mode during Light Load
        3. 7.4.16.3 CHG and PG During Boost Mode
        4. 7.4.16.4 Protection in Boost Mode
          1. 7.4.16.4.1 Output Over-Voltage Protection
          2. 7.4.16.4.2 Output Over-Current Protection
          3. 7.4.16.4.3 Battery Voltage Protection
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application, External Discharge FET
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Output Inductor and Capacitor Selection Guidelines
      2. 8.2.2 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Requirements for SYS Output
    2. 9.2 Requirements for Charging
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 Applications 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.

8.1 Application Information

The bq24266EVM-609 evaluation module (EVM) is a complete charger module for evaluating the bq24266. The application curves were taken using the bq24266EVM-609 (SLUUB40). See Related Documentation.

The bq24266EVM is shipped with the bq24266 populated, For the bq24266, the TS input is available and the resistors are chosen using Equation 3 and Equation 4.

8.2 Typical Applications

8.2.1 Typical Application, External Discharge FET

bq24266 BQ24266_Apps_SLUSBY5.gif Figure 14. bq24266 Typical Application Circuit

8.2.1.1 Design Requirements

Table 4. Design Requirements

DESIGN PARAMATER EXAMPLE VALUE
Input Voltage Range 4.75 V to 5.25 V nominal, withstand 28 V
Input Current Limit 2500 mA
Input DPM Threshold 4.2 V (Externally Set)
Fast Charge Current 3000 mA
Battery Charge Voltage 4.2 V
Termination Current 300 mA

8.2.1.2 Detailed Design Procedure

The parameters are configurable using the EVM jumper options as described in the Users Manual. The typical application for the bq24266EVM is shown in Figure 14. The default IUSB settings are for 2.5A input current limit and external VINDPM threshold, which is IUSB3 = 1, IUSB = 2 = 1, IUSB1 = 0. The VDPM resistors were selected using Equation 1. The charge current, ICHARGE, was set to be 3A using Equation 2.

The typical application circuit shows the minimum capacitance requirements for each pin. Options for sizing the inductor outside the 1.5 μH recommended value and additional SYS pin capacitance are explained in the next section. The resistors on PG and CHG are sized per each LED's current requirements. The TS resistor divider for configuring the TS function to work with the battery's specific thermistor can be computed from Equation 3 and Equation 4. The external battery FET is optional.

8.2.1.2.1 Output Inductor and Capacitor Selection Guidelines

When selecting an inductor, several attributes must be examined to find the right part for the application. First, the inductance value should be selected. The bq24266 is designed to work with 1.5µH to 2.2µH inductors. The chosen value will have an effect on efficiency and package size. Due to the smaller current ripple, some efficiency gain is reached using the 2.2µH inductor, however, due to the physical size of the inductor, this may not be a viable option. The 1.5µH inductor provides a good tradeoff between size and efficiency.

Once the inductance has been selected, the peak current must be calculated in order to choose the current rating of the inductor. Use Equation 7 to calculate the peak current.

Equation 7. bq24266 eq5_ROTP_usba2.gif

The inductor selected must have a saturation current rating greater than or equal to the calculated IPEAK. Due to the high currents possible with the bq24266, a thermal analysis must also be done for the inductor. Many inductors have 40°C temperature rise rating. This is the DC current that will cause a 40°C temperature rise above the ambient temperature in the inductor. For this analysis, the typical load current may be used adjusted for the duty cycle of the load transients. For example, if the application requires a 1.5A DC load with peaks at 2.5A 20% of the time, a Δ40°C temperature rise current must be greater than 1.7A:

Equation 8. ITEMPRISE = ILOAD + D × (IPEAK – ILOAD) = 1.5 A + 0.2 × (2.5 A – 1.5 A) = 1.7 A

The internal loop compensation of the bq24266 is designed to be stable with 10µF to 150µF of local capacitance but requires at least 20µF total capacitance on the SYS rail (10µF local + ≥ 10µF distributed). The capacitance on the SYS rail can be higher than 150µF if distributed amongst the rail. To reduce the output voltage ripple, a ceramic capacitor with the capacitance between 10µF and 47µF is recommended for local bypass to SYS. If greater than 100µF effective capacitance is on the SYS rail, place at least 10µF bypass on the BAT pin. Pay special attention to the DC bias characteristics of ceramic capacitors. For small case sizes, the capacitance can be derated as high as 70% at workable voltages. All capacitances specified in this datasheet are effective capacitance, not capacitor value.

8.2.2 Application Curves

bq24266 TEK115_slusbk7.gif Figure 15. Startup With No Battery
bq24266 TEK116_slusbk7.gif Figure 17. Battery Removal
bq24266 TEK123_slusbk7.gif Figure 19. VSYS Transient With Supplement Mode
bq24266 TEK108_slusbk7.gif Figure 21. Boost Startup No Load
bq24266 TEK106_slusbk7.gif Figure 23. Boost Startup 1A Load
bq24266 TEK873_SLUSBY5.png Figure 25. Input OVP Event with CHG
bq24266 TEK870_SLUSBY5.png
VIN = 5 V
Figure 27. USB Inrush Current, IUSB3 = 0, IUSB2 = 0, IUSB1 = 1
bq24266 TEK872_SLUSBY5.png
VIN = 12 V
Figure 29. Default Startup, IUSB3 = 1, IUSB2 = 1, IUSB1 = 0
bq24266 TEK117_slusbk7.gif Figure 16. Battery Detection
bq24266 TEK119_slusbk7.gif Figure 18. VSYS Transient Without Supplement Mode
bq24266 TEK124_slusbk7.gif Figure 20. VSYS Transient With Supplement Mode
bq24266 TEK587_lusbu4.gif Figure 22. Boost Burst Mode During Light Load
bq24266 TEK592_lusbu4.gif Figure 24. Boost Transient Response
bq24266 startup_4v2_SLUSBU4.gif Figure 26. Startup, 4.2V
bq24266 TEK871_SLUSBY5.png
VIN = 5 V
Figure 28. Default Startup, IUSB3 = 0, IUSB2 = 0, IUSB1 = 1