SLUS968G January   2010  – August 2015


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Device Options
  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 Dissipation Ratings
    6. 8.6 Electrical Characteristics
    7. 8.7 Typical Characteristics
      1. 8.7.1 Power Up, Power Down, OVP, Disable and Enable Waveforms
      2. 8.7.2 Protection Circuits Waveforms
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Power-Down or Undervoltage Lockout (UVLO)
      2. 9.3.2  UVLO
      3. 9.3.3  Power-Up
      4. 9.3.4  Sleep Mode
      5. 9.3.5  New Charge Cycle
      6. 9.3.6  Overvoltage-Protection (OVP) - Continuously Monitored
      7. 9.3.7  Power Good Indication (PG)
      8. 9.3.8  CHG Pin Indication
      9. 9.3.9  CHG and PG LED Pull-Up Source
      10. 9.3.10 IN-DPM (VIN-DPM or IN-DPM)
      11. 9.3.11 OUT
      12. 9.3.12 ISET
      13. 9.3.13 PRE_TERM - Pre-Charge and Termination Programmable Threshold
      14. 9.3.14 ISET2
      15. 9.3.15 TS
    4. 9.4 Device Functional Modes
      1. 9.4.1 Termination and Timer Disable Mode (TTDM) -TS Pin High
      2. 9.4.2 Timers
      3. 9.4.3 Termination
      4. 9.4.4 Battery Detect Routine
      5. 9.4.5 Refresh Threshold
      6. 9.4.6 Starting a Charge on a Full Battery
  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. Calculations
          1. Program the Fast Charge Current, ISET:
          2. Program the Termination Current Threshold, ITERM:
          3. TS Function
          4. CHG and PG
        2. Selecting IN and OUT Pin Capacitors
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
      1. 12.3.1 Leakage Current Effects on Battery Capacity
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 Related Links
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10 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.

10.1 Application Information

The bq2409x series of devices are highly integrated Li-Ion and Li-Pol linear chargers devices targeted at space-limited portable applications. The devices operate from either a USB port or AC adapter. The high input voltage range with input overvoltage protection supports low-cost unregulated adaptors. These devices have a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10 hour safety timer.

10.2 Typical Application

bq24091 bq24092 bq24093 bq24095 bq24090 chg_app_des_lus941.gifFigure 21. Typical Application Schematic

10.2.1 Design Requirements

  • Supply voltage = 5 V
  • Fast charge current: IOUT-FC = 540 mA; ISET-pin 2
  • Termination Current Threshold: %IOUT-FC = 10% of Fast Charge or approximately 54mA
  • Pre-Charge Current by default is twice the termination Current or approximately 108mA
  • TS – Battery Temperature Sense = 10k NTC (103AT)

10.2.2 Detailed Design Procedure Calculations Program the Fast Charge Current, ISET:

from electrical characteristics table. . . K(SET) = 540AΩ
RISET = [540AΩ/0.54A] = 1.0 kΩ
Selecting the closest standard value, use a 1 kΩ resistor between ISET (pin 16) and VSS. Program the Termination Current Threshold, ITERM:

RPRE-TERM = 200Ω/% × 10% = 2kΩ
Selecting the closest standard value, use a 2 kΩ resistor between ITERM (pin 15) and Vss.
One can arrive at the same value by using 20% for a pre-charge value (factor of 2 difference).
RPRE-TERM = 100Ω/% × 20%= 2kΩ TS Function

Use a 10kΩ NTC thermistor in the battery pack (103AT).

To Disable the temp sense function, use a fixed 10kΩ resistor between the TS (Pin 1) and Vss. CHG and PG

LED Status: connect a 1.5kΩ resistor in series with a LED between the OUT pin and the CHG pin.
Connect a 1.5kΩ resistor in series with a LED between the OUT pin and the and PG pin.

Processor Monitoring: Connect a pull-up resistor between the processor’s power rail and the CHG pin.
Connect a pull-up resistor between the processor’s power rail and the PG pin. Selecting IN and OUT Pin Capacitors

In most applications, all that is needed is a high-frequency decoupling capacitor (ceramic) on the power pin, input and output pins. Using the values shown on the application diagram, is recommended. After evaluation of these voltage signals with real system operational conditions, one can determine if capacitance values can be adjusted toward the minimum recommended values (DC load application) or higher values for fast high amplitude pulsed load applications. Note if designed for high input voltage sources (bad adaptors or wrong adaptors), the capacitor needs to be rated appropriately. Ceramic capacitors are tested to 2x their rated values so a 16V capacitor may be adequate for a 30V transient (verify tested rating with capacitor manufacturer).

10.2.3 Application Curves

bq24091 bq24092 bq24093 bq24095 bq24090 fix_ts_lus941.gif
Continuous battery detection when not in TTDM.
Figure 22. Battery Removal with fixed TS = 0.5V
bq24091 bq24092 bq24093 bq24095 bq24090 iset_short_lus941.gif
CH4: Iout (1A/Div)
Figure 24. ISET Shorted During Normal Operation
bq24091 bq24092 bq24093 bq24095 bq24090 batt_chg_lus941.gif
CH4: Iout (1A/Div)
Battery voltage swept from 0V to 4.25V to 3.9V.
Figure 23. Battery Charge Profile
bq24091 bq24092 bq24093 bq24095 bq24090 adaptor_lus941.gif
CH4: Iout (0.2A/Div)
Figure 25. DPM – Adaptor Current Limits – Vin Regulated