SLUSC03C August   2014  – December 2016

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  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. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Battery Only
      2. 8.3.2  Adapter Detect and ACOK Output
        1. 8.3.2.1 Adapter Overvoltage (ACOVP)
      3. 8.3.3  System Power Selection
      4. 8.3.4  System Power Up
        1. 8.3.4.1 Dynamic Power Management (IDPM) and Supplement Mode
        2. 8.3.4.2 Minimum System Voltage Regulation and LDO Mode
      5. 8.3.5  Current and Power Monitor
        1. 8.3.5.1 High Accuracy Current Sense Amplifier (IADP and IBAT)
        2. 8.3.5.2 High Accuracey Power Sense Amplifier (PMON)
      6. 8.3.6  Processor Hot Indication for CPU Throttling
      7. 8.3.7  Converter Operation
        1. 8.3.7.1 Continuous Conduction Mode (CCM)
        2. 8.3.7.2 Discontinuous Conduction Mode (DCM)
        3. 8.3.7.3 PFM Mode
        4. 8.3.7.4 Switching Frequency Adjust
      8. 8.3.8  Learn Mode
      9. 8.3.9  Charger Timeout
      10. 8.3.10 Device Protection Features
        1. 8.3.10.1 Input Overcurrent Protection (ACOC)
        2. 8.3.10.2 Converter Overcurrent Protection
        3. 8.3.10.3 Battery Overvoltage Protection (BATOVP)
        4. 8.3.10.4 System Overvoltage Protection (SYSOVP)
        5. 8.3.10.5 Thermal Shutdown Protection (TSHUT)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Battery Charging
      2. 8.4.2 System Voltage Regulation with Narrow VDC Architecture
    5. 8.5 Programming
      1. 8.5.1 SMBus Interface
        1. 8.5.1.1 SMBus Write-Word and Read-Word Protocols
        2. 8.5.1.2 Timing Diagrams
      2. 8.5.2 I2C Serial Interface
        1. 8.5.2.1 Data Validity
        2. 8.5.2.2 START and STOP Conditions
        3. 8.5.2.3 Byte Format
        4. 8.5.2.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 8.5.2.5 Slave Address and Data Direction Bit
        6. 8.5.2.6 Single Read and Write
        7. 8.5.2.7 Multi-Read and Multi-Write
    6. 8.6 Register Maps
      1. 8.6.1 ChargeOption0 Register
      2. 8.6.2 ChargeOption1 Register
      3. 8.6.3 ChargeOption2 Register
      4. 8.6.4 ProchotOption0 Register
      5. 8.6.5 ProchotOption1 Register
      6. 8.6.6 Setting the Charge Current
      7. 8.6.7 Setting the Maximum Charge Voltage
      8. 8.6.8 Setting the Minimum Charge Voltage
      9. 8.6.9 Setting Input Current
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application, bq24770
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Reverse Input Voltage Protection
        2. 9.2.2.2 Inductor Selection
        3. 9.2.2.3 Input Capacitor
        4. 9.2.2.4 Output Capacitor
        5. 9.2.2.5 Power MOSFETs Selection
        6. 9.2.2.6 Input Filter Design
      3. 9.2.3 Application Curves
      4. 9.2.4 Typical Application, bq24773
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
        3. 9.2.4.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
      1. 11.2.1 Layout Consideration of Current Path
      2. 11.2.2 Layout Consideration of Short Circuit Protection
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    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

Layout

Layout Guidelines

The switching node rise and fall times should be minimized for minimum switching loss. Proper layout of the components to minimize high frequency current path loop (see Figure 37) is important to prevent electrical and magnetic field radiation and high frequency resonant problems. Layout of the PCB according to this specific order is essential.

  • Place input capacitor as close as possible to switching MOSFET’s supply and ground connections and use shortest copper trace connection. These parts should be placed on the same layer of PCB instead of on different layers and using vias to make this connection.
  • The IC should be placed close to the switching MOSFET’s gate pins and keep the gate drive signal traces short for a clean MOSFET drive. The IC can be placed on the other side of the PCB of switching MOSFETs.
  • Place inductor input pin to switching MOSFET’s output pin as close as possible. Minimize the copper area of this trace to lower electrical and magnetic field radiation but make the trace wide enough to carry the charging current. Do not use multiple layers in parallel for this connection. Minimize parasitic capacitance from this area to any other trace or plane.
  • The charging current sensing resistor should be placed right next to the inductor output. Route the sense leads connected across the sensing resistor back to the IC in same layer, close to each other (minimize loop area) and do not route the sense leads through a high-current path (see Figure 38 for Kelvin connection for best current accuracy). Place decoupling capacitor on these traces next to the IC
  • Place output capacitor next to the sensing resistor output and ground
  • Output capacitor ground connections need to be tied to the same copper that connects to the input capacitor ground before connecting to system ground.
  • Use single ground connection to tie charger power ground to charger analog ground. Just beneath the IC use analog ground copper pour but avoid power pins to reduce inductive and capacitive noise coupling
  • Route analog ground separately from power ground. Connect analog ground and connect power ground separately. Connect analog ground and power ground together using power pad as the single ground connection point. Or using a 0Ω resistor to tie analog ground to power ground (power pad should tie to analog ground in this case if possible).
  • Decoupling capacitors should be placed next to the IC pins and make trace connection as short as possible
  • It is critical that the exposed power pad on the backside of the IC package be soldered to the PCB ground. Ensure that there are sufficient thermal vias directly under the IC, connecting to the ground plane on the other layers.
  • The via size and number should be enough for a given current path.

See the EVM design for the recommended component placement with trace and via locations. For the WQFN information, See SCBA017 and SLUA271.

Layout Example

Layout Consideration of Current Path

bq24770 bq24773 hi_f_path_lusa79.gif Figure 37. High Frequency Current Path

Layout Consideration of Short Circuit Protection

bq24770 bq24773 sens_res_layout_lusa79.gif Figure 38. Sensing Resistor PCB Layout