JAJSDJ9D April   2016  – January 2019

PRODUCTION DATA.  

  1. 特長
  2. アプリケーション
  3. 概要
    1.     Device Images
      1.      概略回路図
  4. 改訂履歴
  5. Device Comparison
  6. Pin Configuration and Functions
    1.     Pin 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 Operational Characteristics (Protection Circuits Waveforms)
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Power-Down or Undervoltage Lockout (UVLO)
      2. 8.3.2 Power-up
      3. 8.3.3 Sleep Mode
      4. 8.3.4 New Charge Cycle
      5. 8.3.5 Overvoltage-Protection (OVP) – Continuously Monitored
      6. 8.3.6 CHG Terminal Indication
    4. 8.4 Device Functional Modes
      1. 8.4.1  CHG LED Pull-up Source
      2. 8.4.2  IN-DPM (VIN-DPM or IN-DPM)
      3. 8.4.3  OUT
      4. 8.4.4  ISET
      5. 8.4.5  TS
      6. 8.4.6  Termination and Timer Disable Mode (TTDM) - TS Terminal High
      7. 8.4.7  Timers
      8. 8.4.8  Termination
      9. 8.4.9  Battery Detect Routine
      10. 8.4.10 Refresh Threshold
      11. 8.4.11 Starting a Charge on a Full Battery
  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 Calculations
          1. 9.2.2.1.1 Program the Fast Charge Current, ISET:
          2. 9.2.2.1.2 Pre-Charge and Termination Current Thresholds, ITERM, and PRE-CHG
          3. 9.2.2.1.3 TS Function
          4. 9.2.2.1.4 CHG
        2. 9.2.2.2 Selecting In and Out Terminal Capacitors
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
      1. 11.3.1 Leakage Current Effects on Battery Capacity
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 ドキュメントの更新通知を受け取る方法
    2. 12.2 コミュニティ・リソース
    3. 12.3 商標
    4. 12.4 静電気放電に関する注意事項
    5. 12.5 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

Thermal Considerations

The bq21040 is packaged in a thermally-enhanced MLP package. The package includes a thermal pad to provide an effective thermal contact between the IC and the printed circuit board (PCB). The power pad should be directly connected to the VSS terminal. The most common measure of package thermal performance is thermal impedance (RθJA) measured (or modeled) from the chip junction to the air surrounding the package surface (ambient). The mathematical expression for ψJT is:

Equation 7. ψJT = (TJ – T) / P

where

  • TJ = Chip junction temperature
  • P = Device power dissipation
  • T = Case temperature

Factors that can influence the measurement and calculation of ψJT include:

  1. Whether or not the device is board mounted
  2. Trace size, composition, thickness, and geometry
  3. Orientation of the device (horizontal or vertical)
  4. Volume of the ambient air surrounding the device under test and airflow
  5. Whether other surfaces are in close proximity to the device being tested

Due to the charge profile of Li-Ion and Li-Pol batteries the maximum power dissipation is typically seen at the beginning of the charge cycle when the battery voltage is at its lowest. Typically after fast charge begins the pack voltage increases to ≉3.4V within the first 2 minutes. The thermal time constant of the assembly typically takes a few minutes to heat up so when doing maximum power dissipation calculations, 3.4V is a good minimum voltage to use. This is verified, with the system and a fully discharged battery, by plotting temperature on the bottom of the PCB under the IC (pad should have multiple vias), the charge current and the battery voltage as a function of time. The fast charge current will start to taper off if the part goes into thermal regulation.

The device power dissipation, P, is a function of the charge rate and the voltage drop across the internal PowerFET. It can be calculated from the following equation when a battery pack is being charged:

Equation 8. P = [V(IN) – V(OUT)] × I(OUT) + [V(OUT) – V(BAT)] × I(BAT)

The thermal loop feature reduces the charge current to limit excessive IC junction temperature. It is recommended that the design not run in thermal regulation for typical operating conditions (nominal input voltage and nominal ambient temperatures) and use the feature for non typical situations such as hot environments or higher than normal input source voltage. With that said, the IC will still perform as described, if the thermal loop is always active.