SLVSDH0C December   2016  – January 2018 TPS22810

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Switching Characteristics
    7. 7.7 Typical DC Characteristics
    8. 7.8 Typical AC 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 On and Off Control
      2. 9.3.2 Quick Output Discharge (QOD)
        1. 9.3.2.1 QOD when System Power is Removed
        2. 9.3.2.2 Internal QOD Considerations
      3. 9.3.3 EN/UVLO
      4. 9.3.4 Adjustable Rise Time (CT)
      5. 9.3.5 Thermal Shutdown
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 ON and OFF Control
    3. 10.3 Input Capacitor (Optional)
    4. 10.4 Output Capacitor (Optional)
    5. 10.5 Typical Application
      1. 10.5.1 Design Requirements
      2. 10.5.2 Detailed Design Procedure
        1. 10.5.2.1 Shutdown Sequencing During Unexpected Power Loss
        2. 10.5.2.2 VIN to VOUT Voltage Drop
        3. 10.5.2.3 Inrush Current
      3. 10.5.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Developmental Support
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.5.2.1 Shutdown Sequencing During Unexpected Power Loss

Using the adjustable Quick Output Discharge function of the TPS22810, adding a load switch to each power rail can be used to manage the power down sequencing in the event of an unexpected power loss (that is battery removal). To determine the QOD values for each load switch, first confirm the power down order of the device you wish to power sequence. Be sure to check if there are voltage or timing margins that must be maintained during power down. Next, consult Table 1 to determine appropriate CL and RQOD values for each power rail's load switch so that the load switches' fall times correspond to the order in which they need to be powered down. In the above example, we must have this power rail's fall time to be 4 ms. Using Equation 2, we can determine the appropriate RQOD to achieve our desired fall time.

Since fall times are measured from 90% of VOUT to 10% of VOUT, using Equation 2, we get Equation 4 and Equation 5.

Equation 4. TPS22810 Equation4_SLVSDH0.gif
Equation 5. RQOD = 413.7 Ω

Consulting Figure 6, RPD at VIN = 12 V is approximately 250 Ω. Using Equation 1, the required external QOD resistance can be calculated as shown in Equation 6 and Equation 7.

Equation 6. 413.7 Ω = 250 Ω + REXT
Equation 7. REXT = 163.7 Ω

Figure 22 through Figure 25 are scope shots demonstrating an example of the QOD functionality when power is removed from the device (both ON and VIN are disconnected simultaneously). In the scope shots, the VIN = 12 V and correspond to when RQOD = 1000 Ω, RQOD= 500 Ω, and QOD = VOUT with two values of CL = 10 µF and 22 µF.

TPS22810 Figure22_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 10 µF
Figure 22. Fall Time tF at VIN = 12 V, RQOD = 1000 Ω
TPS22810 Figure24_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 10 µF
Figure 24. tF at VIN = 12 V , QOD = VOUT
TPS22810 Figure26_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 22 µF
Figure 26. tF at VIN = 12 V, RQOD = 500 Ω
TPS22810 Figure23_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 10 µF
Figure 23. Fall Time tF at VIN = 12 V, RQOD = 500 Ω
TPS22810 Figure25_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 22 µF
Figure 25. tF at VIN = 12 V, RQOD = 1000 Ω
TPS22810 Figure27_SLVSDH0.gif
VIN = 12 V CIN = 1 µF CL = 22 µF
Figure 27. tF at VIN = 12 V, QOD = VOUT