JAJSCF6G July   2016  – December  2019 TPS2660

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
    1.     概略回路図
  3. 3 概要
    1.     -60V電源における入力逆極性保護
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 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 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Undervoltage Lockout (UVLO)
      2. 10.3.2 Overvoltage Protection (OVP)
      3. 10.3.3 Reverse Input Supply Protection
      4. 10.3.4 Hot Plug-In and In-Rush Current Control
      5. 10.3.5 Overload and Short Circuit Protection
        1. 10.3.5.1 Overload Protection
          1. 10.3.5.1.1 Active Current Limiting
          2. 10.3.5.1.2 Electronic Circuit Breaker with Overload Timeout, MODE = OPEN
        2. 10.3.5.2 Short Circuit Protection
          1. 10.3.5.2.1 Start-Up With Short-Circuit On Output
        3. 10.3.5.3 FAULT Response
          1. 10.3.5.3.1 Look Ahead Overload Current Fault Indicator
        4. 10.3.5.4 Current Monitoring
        5. 10.3.5.5 IN, OUT, RTN, and GND Pins
        6. 10.3.5.6 Thermal Shutdown
        7. 10.3.5.7 Low Current Shutdown Control (SHDN)
    4. 10.4 Device Functional Modes
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Step by Step Design Procedure
        2. 11.2.2.2 Programming the Current-Limit Threshold—R(ILIM) Selection
        3. 11.2.2.3 Undervoltage Lockout and Overvoltage Set Point
        4. 11.2.2.4 Programming Current Monitoring Resistor—RIMON
        5. 11.2.2.5 Setting Output Voltage Ramp Time—(tdVdT)
          1. 11.2.2.5.1 Case 1: Start-Up Without Load—Only Output Capacitance C(OUT) Draws Current During Start-Up
          2. 11.2.2.5.2 Case 2: Start-Up With Load—Output Capacitance C(OUT) and Load Draws Current During Start-Up
          3. 11.2.2.5.3 Support Component Selections—RFLTb and C(IN)
      3. 11.2.3 Application Curves
    3. 11.3 System Examples
      1. 11.3.1 Acive ORing Operation
      2. 11.3.2 Field Supply Protection in PLC, DCS I/O Modules
      3. 11.3.3 Simple 24-V Power Supply Path Protection
    4. 11.4 Do's and Don'ts
  12. 12Power Supply Recommendations
    1. 12.1 Transient Protection
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14デバイスおよびドキュメントのサポート
    1. 14.1 デバイス・サポート
    2. 14.2 ドキュメントのサポート
      1. 14.2.1 関連資料
    3. 14.3 ドキュメントの更新通知を受け取る方法
    4. 14.4 コミュニティ・リソース
    5. 14.5 商標
    6. 14.6 静電気放電に関する注意事項
    7. 14.7 Glossary
  15. 15メカニカル、パッケージ、および注文情報

11.2.2.5.2 Case 2: Start-Up With Load—Output Capacitance C(OUT) and Load Draws Current During Start-Up

When the load draws current during the turnon sequence, additional power is dissipated in the device. Considering a resistive load RL(SU) during start-up, typical ramp-up of output voltage, load current and the instantaneous power dissipation in the device are shown in Figure 53. Instantaneous power dissipation with respect to time is plotted in Figure 54. The additional power dissipation during start-up is calculated using Equation 17.

TPS2660 Pd with 48ohm.png
VIN = 24 V RL(SU) = 48 Ω
CdVdT = 2.2 µF COUT = 2.2 mF
Figure 53. Start-Up With Load
TPS2660 D051_SLVSDG2.gif
VIN = 24 V RL(SU) = 48 Ω
CdVdT = 2.2 µF COUT = 2.2 mF
Figure 54. PD(INRUSH) Due to Inrush and Load Current
Equation 17. TPS2660 Equation_9_App2.gif

Total power dissipated in the device during start-up is given by Equation 18.

Equation 18. TPS2660 Equation_10_App2.gif

Total current during start-up is given by Equation 19.

Equation 19. TPS2660 Equation_11_App2.gif

For the design example under discussion,

Select the inrush current I(INRUSH) = 0.1 A and calculate tdVdT using Equation 20.

Equation 20. TPS2660 Equation_12_App2.gif

For a given start-up time, CdVdT capacitance value is calculated using Equation 21.

Equation 21. TPS2660 Equation_13_App2.gif

where

  • t(dVdT) = 0.528 s
  • V(IN) = 24 V

Choose the closest standard value: 2.2-µF/16-V capacitor.

The inrush power dissipation is calculated, using Equation 22.

Equation 22. TPS2660 Equation_14_App2.gif

where

  • V(IN) = 24 V
  • I(INRUSH) = 0.1 A

Considering the start-up with 48-Ω load, the additional power dissipation, is calculated using Equation 23.

Equation 23. TPS2660 Equation_15_App2.gif

where

  • V(IN) = 24 V
  • RL(SU) = 48 Ω

The total device power dissipation during start-up is given by Equation 24.

Equation 24. TPS2660 Equation_16_App2.gif

where

  • PD(INRUSH) = 1.2 W
  • PD(LOAD) = 2 W

The power dissipation with or without load, for a selected start-up time must not exceed the thermal shutdown limits as shown in Figure 55.

From the thermal shutdown limit graph, at TA = 85°C, thermal shutdown time for 3.2 W is close to 28000 ms. It is safe to have a minimum 30% margin to allow for variation of the system parameters such as load, component tolerance, input voltage and layout. Selected 2.2-µF CdVdT capacitor and 528-ms start-up time (tdVdT) are within limit for successful start-up with 48-Ω load.

Higher value C(dVdT) capacitor can be selected to further reduce the power dissipation during start-up.

TPS2660 D052_SLVSDG2.gifFigure 55. Thermal Shutdown Time vs Power Dissipation