SLVSDT4F October   2017  – December 2021 TPS2662

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 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. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Undervoltage Lockout (UVLO)
      2. 9.3.2 Overvoltage Protection (OVP)
      3. 9.3.3 Hot Plug-In and Inrush Current Control
      4. 9.3.4 Reverse Polarity Protection
        1. 9.3.4.1 Input Side Reverse Polarity Protection
        2. 9.3.4.2 Output Side Reverse Polarity Protection
      5. 9.3.5 Overload and Short-Circuit Protection
        1. 9.3.5.1 Overload Protection
        2.       28
        3. 9.3.5.2 Short-Circuit Protection
          1. 9.3.5.2.1 Start-Up With Short-Circuit On Output
      6. 9.3.6 Reverse Current Protection
      7. 9.3.7 FAULT Response
      8. 9.3.8 IN, OUT, RTN, and GND Pins
      9. 9.3.9 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 Low Current Shutdown Control (SHDN)
  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. 10.2.2.1 Step-by-Step Design Procedure
        2. 10.2.2.2 Programming the Current Limit Threshold R(ILIM) Selection
        3. 10.2.2.3 Undervoltage Lockout and Overvoltage Set Point
        4. 10.2.2.4 Setting Output Voltage Ramp Time—(tdVdT)
          1. 10.2.2.4.1 Case 1: Start-Up Without Load—Only Output Capacitance C(OUT) Draws Current During Start-Up
          2. 10.2.2.4.2 Case 2: Start-Up With Load —Output Capacitance C(OUT) and Load Draws Current During Start-Up
          3. 10.2.2.4.3 Support Component Selections – R FLT and C(IN)
      3. 10.2.3 Application Curves
    3. 10.3 System Examples
      1. 10.3.1 Field Supply Protection in PLC, DCS I/O Modules
      2. 10.3.2 Simple 24-V Power Supply Path Protection
      3. 10.3.3 Power Stealing in Smart Thermostat
    4. 10.4 Do's and Don'ts
  11. 11Power Supply Recommendations
    1. 11.1 Transient Protection
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Support Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
10.2.2.4.2 Case 2: Start-Up With Load —Output Capacitance C(OUT) and Load Draws Current During Start-Up

When the load draws current during the turn-on sequence, additional power is dissipated in the device. Considering a resistive load RL(SU) during start-up, typical ramp-up of output voltage, Figure 10-4 shows load current and the instantaneous power dissipation in the device. Figure 10-5 plots Instantaneous power dissipation with respect to time.

GUID-8AADD358-6FDD-4698-A82B-6CB1B489A240-low.png
VIN = 24 VRL(SU) = 96 Ω
CdVdT = 10 nFCOUT = 22 µF
Figure 10-4 Start-Up With Load
GUID-53173B68-B721-46B5-942F-F67C963FB7D7-low.gif
VIN = 24 VRL(SU) = 96 Ω
CdVdT = 10 nFCOUT = 22 µF
Figure 10-5 PD(INRUSH) Due to Inrush and Load Current

The additional power dissipation during start-up is calculated using Equation 10.

Equation 10. GUID-C15FE71B-7AEE-4584-A4EF-BAFBFA040E46-low.gif

Total power dissipated in the device during start-up is given by Equation 11.

Equation 11. GUID-334DFA47-3FA8-449D-A167-D7AE9932E978-low.gif

Total current during start-up is given by Equation 12.

Equation 12. GUID-E6BF073A-FE79-4897-BBA9-EEDEF788E64D-low.gif

For the design example under discussion,

Select the inrush current I(INRUSH) = 0.1 A and tdVdT calculated using Equation 8 is 5.28 ms.

For a given start-up time, CdVdT capacitance value calculated using Equation 2 is 10.7 nF for tdVdT = 5.28 ms and VIN = 24 V.

Choose the closest standard value: 10.0 nF and 16-V capacitor.

The inrush power dissipation due to output capacitor alone is calculated using Equation 9 and it is 1.2 W. Considering the start-up with 96-Ω load, the additional power dissipation calculated using Equation 10 is 1 W. The total device power dissipation during start-up is 2.2 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 10-6.

From the thermal shutdown limit graph, at TA = 125°C, thermal shutdown time for 2.2 W is close to 580 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 10-nF CdVdT capacitor and 5.28-ms start-up time (tdVdT) are well within the limit for successful start-up with 96-Ω load.

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

GUID-297CF9A2-9F27-4F9F-9EC3-210CC52F419D-low.gifFigure 10-6 Thermal Shutdown Time vs Power Dissipation